text: referring to fig3 reference character 30 designates a gaas substrate 300 μm thick , and an epitaxial gaas l - x p x is made up of a pair of layers 32 and 34 . the layer 32 is a gaas l - x p x transition layer whose mixed crystal ratio x is gradually increased from 0 to 0 . 40 , while the layer 34 is an epitaxial gaas l - x p x constant layer whose mixed crystal ratio x is constant , or about 0 . 04 . the thickness of the layer 32 is made larger than 10 μn and preferably more than 30 μm . the thickness of the layer 34 is also preferably more than 10 μm although it is not critical . in this example , the thicknesses of the layer 32 and 34 are selected as 30 μm , respectively . reference character s designates an interface or layer which is formed by at least reducing temporarily the supply of at least one of the components i . e . iii component ( gallium chloride formed by the reaction of hydrogen chloride and gallium ) or v component ( hydrogen arsenide and hydrogen phosphide ) during the process of forming the constant layer 34 . referring to fig4 reference character 40 designates a gap monocrystal layer 300 μm in thickness , and an epitaxial region is made up of four layers 42 , 44 , 46 and 48 . more specifically , the layer 42 is a gap homoepitaxial layer 10 μm in thickness , the layer 44 is a gaas l - x p x transition layer 30 μm in thickness whose mixed crystal ratio x is gradually decreased from 1 . 0 to 0 . 85 , the layer 46 is a gaas l - x p x constant layer 40 μm in thickness whose mixed crystal ratio x is constant , and about 0 . 85 , and the layer 48 is a second gaas l - x p x constant layer 20 μm whose mixed crystal ratio x is constant , and about 0 . 85 , which is similar to the layer 46 , but to which nitrogen ( n ) is added . reference character s indicated in the first constant layer 46 designates an interface or layer which is formed by at least reducing temporarily the supply of at least one of iii component ( gallium chloride formed by the reaction of hydrogen chloride and gallium ) and v component ( hydrogen arsenide and hydrogen phosphide ), during the process of forming the layer 46 . this invention has been developed on the basis of the finding that , as shown in fig3 and 4 , the brightness of the light emissive diode is remarkably improved by providing the layer formed by at least reducing temporarily the supply of at least one of the group iii component and the group v component forming the gaas l - x p 2 constant layer having a constant mixed crystal ratio . the reason for the remarkable improvement on the light emission efficiency of the wafer thus prepared is not always clear . however , the following consideration may apply . in general , with the substrate and an epitaxial film formed on the substrate , various crystallographic defects may be created in the epitaxial film because of the differences in the amount of impurities added to the film and in the crystal lattice constant . the number of these various crystallographic defects thus created may tend to continuously and gradually decrease as the epitaxial film grows . in this invention , it is considered that , with respect to the number of various crystallographic defects the continuity of distribution of the crystallographic defects in the epitaxial layer is interrupted by reducing or interrupting temporarily the supply of at least one of the group iii and v components , as a result of which the crystal perfection of the epitaxial film itself may be markedly improved and electron - photon conversion efficiency is also improved , causing the light emission efficiency to be increased . as conducive to a full understanding of the invention , examples thereof will be described . a gaas monocrystal substrate which is doped with silicone ( si ) as an n - type impuritiy and has a carrier density of 6 . 8 × 10 17 atoms / cm 2 and whose crystallographic plane orientation is deviated by 2 ° from ( 100 ) towards & lt ; 110 & lt ; was provided . the thickness of the gaas monocrystal substrate was about 350 μm at the beginning , but it was reduced to 305 μm through a degreasing process with an organic solvent and through a mechanical - chemical polishing process by which distortion of the substrate is removed . the polished gaas monocrystal substrate and a quartz boat containing high purity ga were placed in predetermined positions in a horizontal type quartz epitaxial reactor 78 mm in inner diameter and 100 cm in length . argon ( ar ) was introduced into the epitaxial reactor to sufficiently replace the air therein . then , a high purity hydrogen gas ( h 2 ) was introduced thereinto as a carrier gas at 2000 cc / min ., and the introduction of the argon gas was suspended , to start the temperature increasing process . after confirming that the quartz boat setting region and the substrate setting region were maintained at 750 ° c . and 810 ° c ., respectively , an epitaxial run of gaas l - x p x film was started . upon start of the epitaxial growth , diethyl tellurim [( c 2 h 5 ) 2 te ] diluted to a concentration of 20 ppm by hydrogen ( h 2 ) was introduced at a rate of 15 cc / min . on the other hand , a high purity hydrogen chloride gas ( hcl ) was introduced at a rate of 20 cc per minute to react with the gallium in the quartz board to obtain gacl . on the other hand , during the initial 90 minutes , the flow rate of hydrogen arsenide ( ash 3 ) diluted to 12 % in concentration by hydrogen ( h 2 ) was gradually decreased from 283 cc / min . to 220 cc / min ., while the flow rate of hydrogen phosphide ( ph 3 ) diluted to 12 % in concentration by hydrogen ( h 2 ) was gradually increased from 0 cc / min . to 63 cc / min ., so as to form a gaas l - x p x transition layer ( 32 in fig3 ), and then formation of a gaas l - x p x constant layer ( 34 in fig3 ) was effected . thereafter , the above - described ( c 2 h 5 ) 2 te , gacl , ash 3 and ph 3 were introduced at constant flow rates of 15 cc / min ., 20 cc / min ., 220 cc / min . and 63 cc / min . respectively , to form the gaas l - x p x constant layer ( 34 in fig3 ), during 95 minutes except five minutes required for suspending the supply of the main component for the purpose of forming the intermediate region in the gaas 1 - x p x constant layer 34 , that is , the layer s in the layer 34 . thus , the epitaxial run was ended . a light emmitting diode was manufactured from the epitaxial wafer obtained by this epitaxial run , and the properties thereof were examined . for comparison , the epitaxial runs according to the invention and epitaxial runs according to the conventional method in which the same epitaxial reactor was used were alternately carried out . the data in the case where , according to this invention , the suspending time of supply is 5 minutes , and the main component to be suspended is the group iii component ( the supply of hcl which reacts with ga to form gacl being suspended ) are indicated in table 1 . the data in the case where the component to be suspended is the group v components ( the supply of ash 3 and ph 3 being suspended ) are indicated in table 2 . the data in the case where the components to be suspended are both of the group iii and v components ( the supply of hcl , ash 3 and ph 3 being suspended ) are indicated in table 3 . in addition , the data of the materials obtained by the conventional epitaxial run are also indicated in tables 1 , 2 and 3 for comparison . table 1______________________________________present method ( the supply of the group iiicomponent only , suspended ) conventional method brightnessepitaxial run brightness ( ft . l ) ofno . ( ft . l ) of led epitaxial run no . led______________________________________no . 1 1440 no . 2 700no . 3 1450 no . 4 750no . 5 1470 no . 6 790no . 7 1500 no . 8 790no . 9 1430 no . 10 670average of average offive runs 1458 five runs 740______________________________________ table 2______________________________________present method ( the supply of the groupcomponent only , suspended ) conventional methodepitaxial run brightness epitaxial run brightness ( ft . l ) no . ( ft . l ) of led no . of led______________________________________1 1400 2 6053 1380 4 7005 1440 6 7207 1270 8 6709 1370 10 800average of average offive runs 1372 five runs 708______________________________________ table 3______________________________________present method ( thesupplies of the group iii andv components , suspended ) conventional methodepitaxial run brightness epitaxial run brightness ( ft . l ) no . ( ft . l ) of led no . of led______________________________________1 1180 2 7503 1240 4 7105 1130 6 6507 1190 8 7909 1200 10 760average of average offive runs 1118 five runs 732______________________________________ diodes were cut out from the epitaxial gaas l - x p x wafers according to this invention and according to the conventional method and their properties were examined by various measuring methods such as a chemical corrosion method ( staining method ), an x - ray diffraction method , a photoluminescence method , a capacity - voltage method ( c - v method ) and a hall effect method . the results were as follows : ( a ) the thickness of the gaas l - x p x transition layer was 30 μm ± 3 μm , and the thickness of the gaas l - x p x constant layer was 30 μm ± 2 μm . these layers of the epitaxial wafers were subjected to chemical corrosion ( staining ) with a hf - h 2 o 2 mixture solution . with the gaas l - x p x epitaxial layer ( the layer s in the layer 34 in fig3 ) caused by suspending the main component supply during the epitaxial process was clearly observed as a chemical corrosion line ( staining line ) in the middle region of the constant layer , by means of a microscope . ( b ) the mixed crystal ratio x in the gaas l - x p x constant layer was 0 . 39 ± 0 . 01 . ( c ) the gaas l - x p x epitaxial film showed n - type conductivity , and the carrier density thereof was ( 7 ± 2 )× 10 16 atoms / cm 2 . the epitaxial gaas l - x p x wafers manufactured according to the present method and to the conventional method were subjected to a thermal diffusion with high purity zinc arsenide ( znas 2 ) for two hours at 750 ° c . to form p - n junctions . after the thermal diffusion , the rear surface of each wafer was polished , and ohmic electrodes were provided on both surfaces of the wafer . furthermore , a series of assembling operations such as dicing and wire - bonding were given to each wafer , to provide a light emitting diode . from the light emitting diodes thus provided , twenty light emitting diodes were sampled at random for every epitaxial run . then , under the conditions of the forward current density of 10 a / cm 2 and no epoxy resin coating the brightness of each light emitting diode thus sampled was measured . the mean value of the brightness of the twenty light emitting diodes was calculated and employed as the brightness value of that epitaxial run . as is indicated in the above tables 1 and 2 , the brigthness of the diodes according to the present method is improved as much as about 90 % when compared with that according to the conventional method . furthermore , as is apparent from the above table 3 , the brightness of the diodes according to the method of this invention is improved as much as about 60 % when compared with that according to the conventional method . thus , the effect of this invention has been confirmed . the above - described example 1 relates to the manufacture of epitaxial gaas l - x p x wafers for red light emitting diodes . the conditions for manufacturing the wafers are that ( 1 ) the main component supply suspending time is set to five minutes , ( 2 ) the number of times of suspending the main component supply is only one during the formation of the constant layer and ( 3 ) the supply of the main component is suspended at the middle region in the gaas 1 - x p x constant layer ( the layer 34 in fig3 ). in this connection , the main component supply suspending time was varied in the range of from 1 minute to 30 minutes with respect to the condition ( 1 ), the number of times of suspending the supply was changed to two and three with respect to the condition ( 2 ), and the supply of the main component was suspended at a region other than the middle region in the gaas 1 - x p x composition constant layer 34 , for instance , at a region at a distance corresponding to 1 / 3 of the thickness of the layer 34 from the surface thereof in the layer 34 ; however , substantially equivalent results were obtained . a gap monocrystal substrate which was doped with sulfur ( s ) as an n - type impurity and had a carrier density of 7 . 5 × 10 17 and whose crystallographc face direction deviated by 5 ° from ( 100 ) towards 110 was prepared . the initial thickness of the gap monocrystal substrate was about 340 μm . it was thinned to 280 μm through a degreasing process with an organic solvent and through a mechanical - chemical polishing process in which any distortion thereof was removed . then , the polished gap monocrystal substrate and a quartz boat containing high pruity ga were placed in predetermined positions in a horizontal type quartz epitaxial reactor 78 mm in inner diameter and 100 cm in length . argon ( ar ) was introduced into the epitaxial reactor to sufficiently replace the air therein . then , high purity hydrogen gas ( h 2 ) was introduced as a carrier gas thereinto at 2000 cc / min , and the introduction of the argon gas was suspended , to start the temperature increasing process . after confirming that the quartz boat setting region and the substrate setting region were maintained at 750 ° c . and 870 ° c ., respectively , an epitaxial run of gaas 1 - x p x was started . upon start of the epitaxy , hydrogen sulfide ( h 2 s ) diluted to a concentration of 50 ppm by nitrogen gas was introduced at a rate of 17 cc / min . on the other hand , a high purity hydrogen chloride gas ( hcl ) was introduced to the gallium at a rate of 45 cc / min to obtain gacl through the reaction with hcl and the gallium ( ga ). on the other hand , during the initial 15 minutes , hydrogen phosphide diluted to a concentration of 12 % by hydrogen ( h 2 ) was introduced at a rate of 300 cc / min , so that the gap layer ( 42 in fig4 ) was obtained on the gap monocrystal substrate through homoepitaxial growth . thereafter , hydrogen arsenide ( ash 3 ) diluted to a concentration of 12 % by ph 3 and h 2 was introduced to start heteroepitaxial growth of gaas 1 - x p x . in other words , during the next 60 minutes while the flow rates of the h 2 s and hcl were maintained at 17 cc / min and 45 cc / min , respectively , the flow rate of ph 3 was gradually decreased from 300 cc / min to 261 cc / min , and , on the other hand , the flow rate of ash 3 was gradually increased from 0 cc / min to 39 cc / min , thereby to form the gaas 1 - x p x transition layer ( 44 in fig4 ). thereafter , formations of the first and second gaas 1 - x p x constant layers ( 46 and 48 in fig4 ) were effected . more specifically , in the subsequent 95 minutes except five minutes required for suspending the supply of the main component for the purpose of forming the intermediate region in the first gaas 1 - x p x constant layer , that is , the layer s in the layer 46 , i . e ., during substantially 90 minutes , the flow rates of the above - described h 2 s , hcl , ph 3 and ash 3 were maintained at 17 cc / min , 45 cc / min , 261 cc / min and 39 cc / min , respectively , to form the first constant gaas 1 - x p x constant layer 46 . furthermore , during 40 minutes after the 95 minutes , while the flow rates of the aforementioned h 2 s , hcl , ph 3 and ash 3 were maintained at 17 cc / min , 45 cc / min , 261 cc / min and 39 cc / min , respectively , high purity ammonia gas ( nh 3 ) was introduced at 200 cc / min , to form the second gaas 1 - x p x constant layer 48 doped with nitrogen ( n ). thus , the epitaxial run was completed . a light emitting diode was manufactured from the epitaxial wafer obtained by this epitaxial run , and properties thereof were examined . the data in the case where , according to this invention , the main component supply suspending time is 5 minutes , and the main component whose supply is suspended is a group iii component ( the supply of hcl which reacts with ga to form gacl being suspended ) are indicated in table 4 . the data in the case where the main component the supply of which is suspended is a group v component ( the supply of ash 3 and ph 3 being suspended ) are indicated in table 5 and the data in the case where the main components the supply of which is suspended are both of the group iii component and the group v component ( the supply of hcl , ash 3 and ph 3 being suspended ) are indicated in table 6 with data obtained from the diodes prepared according to the conventional runs which were carried out alternately . table 4______________________________________present method ( supply of group iiicomponent only , suspended conventional methodepitaxial run brightness epitaxial run brightnessno . ( ft . l ) of led no . ( ft . l ) of led______________________________________1 2550 2 14503 2800 4 13805 2650 6 14907 2700 8 1370average of average offour runs 2675 four runs 1423______________________________________ table 5______________________________________present method ( supply of group vcomponent only , suspended ) conventional methodepitaxial run brightness epitaxial run brightnessno . ( ft . l ) of led no . ( ft . l ) of led______________________________________1 3100 2 14003 3050 4 13905 2900 6 15007 2930 8 1440average of average offour runs 2995 four runs 1433______________________________________ table 6______________________________________present method ( supply of both group iiiand v components , suspended ) conventional methodepitaxial run brightness epitaxial run brightnessno . ( ft . l ) of led no . ( ft . l ) of led______________________________________1 1930 2 14903 2100 4 15105 1850 6 14807 1900 8 1390average of average offour runs 1945 four runs 1468______________________________________ diodes were cut out from the epitaxial wafers according to this invention and the gaas 1 - x p x epitaxial wafers according to the conventional method and their properties were examined by a variety of measuring methods such as a chemical corrosion method ( staining method ), an x - ray diffraction method , a photoluminescence method , a low - temperature light absorption method , a capacity - voltage ( c - v ) method and a hall effect method . the results were as follows : ( a ) the thickness of the gap homoepitaxial layer was 10 ± 2 μm , the thickness of the gaas 1 - x p x transition layer was 35 ± 4 μm , the thickness of the first gaas 1 - x p x constant layer was 45 ± 4 μm , and the thickness of the second gaas 1 - x p x constant layer was 18 ± 3 μm . the gaas 1 - x p x epitaxial wafers manufactured according to the present method were measured in accordance with the chemical corrosion method ( staining method ) with a hf - h 2 o 2 mixture solution , as a result of which a line caused by suspending the main component supply during the epitaxial process was clearly observed as a chemical corrosion line ( staining line ) in the middle region of the first gaas 1 - x p x constant layer ( 46 in fig4 ), by means of a microscope . ( b ) the mixed crystal ratio x in the second gaas 1 - x p x constant layer was 0 . 85 ± 0 . 01 . ( c ) the gaas 1 - x p x epitaxial layer showed n - type conductivity , the carrier density was ( 8 ± 2 )× 10 16 atoms / cm 2 and the nitrogen ( n ) density was 9 × 10 18 atoms / cm 2 . the gaas 1 - x p x epitaxial wafers manufactured according to the method of the invention and to the conventional method were subjected to thermal diffusin with a high purity zinc phospide ( znp 2 ) for 150 minutes at 750 ° c . to form p - n junctions . furthermore , as in the case of red light emitting diodes , a series of assembling operations were performed to obtain yellow light emitting diodes . from the light diodes thus obtained , twenty diodes were sampled at random for every epitaxial run . then , under the conditions of a forward current density of 20 a / cm 2 and no epoxy resin coating , the brightness of each light emitting diode thus sampled was measured . the mean value of the brightness of the twenty diodes was calculated , and employed as the brightness value of that epitaxial run . as is indicated in table 4 , the brightness of the light emitting diode manufactured according to the present method in which the supply of the group iii component is suspended is improved as much as about 80 % when compared with that of the light emitting diode manufactured according to the conventional method . as is clear from table 5 , the brightness of the diode manufactured according to the method of the invention in which the supply of the group v component is suspended is improved as much as about 100 % when compared with that of the light emitting diode according to the conventional method . furthermore , as is apparent from table 6 , the brightness of the diode manufactured according to the present method in which the supply of both of the group iii and v components is suspended is improved as much as about 30 % when compared with that of the light emitting diode according to the conventional method . thus , as in the case of red light emitting diodes , the effect of this invention has been confirmed . the above - described example 2 relates to the manufacture of epitaxial gaas 1 - x p x wafers for yellow light emitting diodes . the conditions for manufacturing the wafers are , that ( 1 ) the main component supply suspending time is set to five minutes , ( 2 ) the number of times of suspending the main component supply is only one during the epitaxy , and ( 3 ) the supply of the main component is suspended at the middle region in the first gaas 1 - x p x constant layer ( 46 in fig4 ). in this connection , as in the case of epitaxial gaas 1 - x p x wafers for red light emitting diodes , the suspending time of the main component supply was varied in the range from 1 minute to 30 minutes with respect to the condition ( 1 ), the number of times of suspending the supply was changed to two and three with respect to the condition ( 2 ), and the supply of the main component was suspended at a region other than the middle region in the first gaas 1 - x p x constant layer 46 , for instance , at a region at a distance corresponding to 1 / 3 of the thickness of the layer 46 , however , substantially equivalent results were obtained . description hereinbelow is for the examples in which the supply of at least one of the group iii and v components is stopped temporarily during the formation of the constant layer 34 ( fig3 ) and 46 ( fig4 ). substantially the same effect can be obtained by merely reducing temperarily the supply of at least one of the semiconductor components , instead of the complete suspension of it . the degree of reduction of the semiconductor component supply may be less than 90 % of the amount of supply required for obtaining the desired mixed crystal ratio . preferably , the reduction of the supply amount of the group iii component or the group v component is 50 % to 1 % of the amount required for the formation of the layer 34 or 46 . where the number of the group iii and / or v elements is two or more , all the amounts of supply of the elements in the same group should be changed . a chemically polished gallium arsenide monocrystal substrate having a surface which is deviated by 2 ° in the direction [ 111 ] from the plane ( 100 ) was loaded in a horizontal type quartz epitaxial reactor having inner diameter 80 mm and length 100 cm . a quartz container filled with metallic gallium ( ga ) was put in place in the reactor . after the air in the reactor was replaced by argon ( ar ), the temperature at sections of the epitaxial reactor where the substrate and the metallic gallium were placed were set to 810 ° c . and 790 ° c ., respectively , and then epitaxial growth of a layer consisting of gallium arsenide phosphide having a mixed crystal ratio of 0 . 4 was started . upon start of the epitaxial growth of the layer , diethyltellurium [( c 2 h 5 ) 2 te ] diluted to a concentration of 20 ppm ( by volume ) with hydrogen gas was introduced at a flow rate of 20 cc / min . hydrogen chloride was introduced at a flow rate of 25 cc / min . to be reacted with the metallic gallium , and the resultant gallium chloride ( gacl ) was supplied to the section of the reactor where the substrate was loaded . in order to form the transition layer 2 , hydrogen gas containing arsine ( ash 3 ) 12 % ( volume ratio ) was supplied at a flow rate of 280 cc / min . at the beginning , and the flow rate was gradually reduced to 220 cc / min . for 90 minutes thereafter . on the other hand , the amount of supply of hydrogen gas containing phosphine ( ph 3 ) 12 % was increased from 0 cc / min . to 60 cc / min . for 90 minutes . thereafter , for 40 minutes , hydrogen gas containing 10 ppm . diethyltellurium , hydrogen chloride , hydrogen gas containing 12 % arsine , and hydrogen gas containing phosphine 12 % were supplied respectively at the flow rates of 20 cc / min , 25 cc / min ., 220 cc / min ., and 60 cc / min ., whereby a epitaxial layer of gallium arsenide phosphide having a mixed crystal ratio of 0 . 4 was formed . thereafter , for 10 minutes , the amount of supply of hydrogen chloride only was reduced to 5 cc / min . to form the transition layer . then , the amount of supply of hydrogen chloride was increased to 25 cc / min , and , for 60 minutes , the formation of the constant layer having a mixed crystal ratio 0 . 4 was effected . thus , the reaction was ended . in the epitaxial layers thus formed , the thickness of the transition layer ( 32 in fig3 ) next to the substrate was 35 μm , the thickness of the first constant layer ( lower portion of 34 in fig3 ) was 14 μm , the thickness of the transition layer ( s in fig3 ) was 0 . 1 μm , and the thickness of the second constant layer ( upper portion of 34 in fig3 ) was 21 μm . in order to investigate the reproducibility of experiment 1 , vapor growth of an epitaxial film consisting of gallium arsenide phosphide ( gaas 0 . 6 p 0 . 4 ) was repeated four times under the same conditions as those in experiment 1 . a chemically polished gallium phosphide monocrystal substrate having a surface which is deviated by 4 ° in the direction & lt ; 100 & gt ; from the plane ( 100 ) was loaded in an epitaxial reactor similar to that employed in example 3 . a quartz container filled with metallic gallium was put in place in the reactor . after the air in the reactor was replaced by argon ( ar ) gas , hydrogen gas was introduced at 2000 ml / min . and the supply of the argon gas was suspended . thereafter , the temperature was increased , so that the sections of the reactors where the substrate and the metallic gallium were placed were set to 860 ° c . and 760 ° c ., respectively . then , an epitaxial growth of a layer consisting of gallium arsenide phosphide ( gaas 1 - x p x ) having mixed crystal ratio of 0 . 86 was started . that is , hydrogen gas containing hydrogen sulfide 50 ppm and hydrogen chloride were introduced into the reactor at 20 cc / min . and 40 cc / min ., respectively . furthermore , hydrogen gas containing phosphine 12 % was supplied at 310 cc / min . for 15 minutes to form a homoepitaxial layer consisting of gallium phosphide . thereafter , the amount of supply of the hydrogen gas containing phosphine was gradually reduced to 260 cc / min . from 310 cc / min . for 60 minutes , and the amount of supply of hydrogen gas containing arsine 12 % was gradually increased to 40 cc / min . from 0 cc / min . to form a transition layer . after reaching the above - described values , the amount of supply of arsine and phosphine were maintained unchanged , and furthermore a formation of a constant layer was carried out for 40 minutes . then , the amount of supply of the hydrogen chloride was reduced to 4 cc / min to continue the reaction for 15 minutes , whereby a transition layer was formed . in 15 minutes , the amount of supply of the hydrogen chloride was restored to 40 cc / min . so as to grow a constant layer for 50 minutes . furthermore , without changing the amounts of supply described above , ammonia ( nh 3 ) was introduced into the reactor at 180 cc / min ., and a nitrogen - doped layer was allowed to grow as an iso - electronic layer for 45 minutes . thus , the reaction was ended . in the epitaxial film obtained by this example , the thickness of gallium phosphide homoepitaxial layer ( 42 in fig4 ), the transition layer ( 44 in fig4 ), the constant layer ( lower portion of 46 in fig4 ), the transition layer ( s in fig4 ), the constant layer ( upper portion of 46 in fig4 ), and the nitrogen doped layer ( 48 in fig4 ) were 11 μm , 34 μm , 30 μm , 0 . 11 μm , 34 μm and 20 μm , respectively . this was measured by using a chemical corrosion method . in order to investigate the reproducibility of the abovediscribed experiment 1 , the formation of an epitaxial layer consisting of gallium arsenide phosphide ( gaas 0 . 14 p 0 . 86 ) was repeated three times , under the same conditions as those in experiment 1 . under the same conditions as those in example 3 , an epitaxial layer consisting of gallium arsenide phosphide ( gaas 0 . 6 p 0 . 4 ) having no transition layer was formed . this experiment was repeated five times . under the same conditions as those in example 3 , an epitaxial layer consisting of gallium arsenide phosphide ( gaas 0 . 14 p 0 . 86 ) having no transition layer was formed . this experiment was repeated four times . the brightness of red light emitting diodes ( peak wavelength being 660 ± 10 nm ) made of the epitaxial films manufactured as described in example 3 and comparison example 3 is indicated in table 7 . the brightness was measured with a current density of 10 a / cm 2 . the brightness of yellow light emitting diodes ( peak wavelength being 590 ± 10 nm ) made of the epitaxial films manufactured as described in example 4 and comparison example 4 is indicated in table 8 below . the brightness was measured with a current density of 20 a / cm 2 . table 7______________________________________ brightness comparison brightnessexample 3 ( ft - l ) example 3 ( ft - l ) ______________________________________experiment 1 1210 experiment 1 750experiment 2 1230 experiment 2 730experiment 3 1100 experiment 3 680experiment 4 1250 experiment 4 850experiment 5 1040 experiment 5 780______________________________________ table 8______________________________________ brightness comparison brightnessexample 4 ( ft - l ) example 4 ( ft - l ) ______________________________________experiment 1 2400 experiment 1 1560experiment 2 2080 experiment 2 1610experiment 3 2350 experiment 3 1440experiment 4 2530 experiment 4 1430______________________________________ it is obvious to those skilled in the art that , in addition to the above - described examples , the technical concept of the invention can be applied to the manufacture of the following epitaxial wafers : ( 1 ) epitaxial gaas wafers for infrared emission diodes and epitaxial gaas 1 - x p x ( 0 & lt ; x & lt ; 0 . 3 ) wafers for high - speed response infrared emission diodes , which may be formed on gaas monocrystal substrates , and epitaxial gaas 1 - x p x wafers for orange emission diodes and epitaxial gap wafers for green emission diodes , which are formed on gap monocrystal substrates . ( 2 ) epitaxial gaas wafers for infrared emission diodes , epitaxial gaas 1 - x p x wafers for high - speed response infrared emission diodes , epitaxial gaas 1 - x p x wafers for red emission diodes , and epitaxial gaas 1 - x p x wafers for orange emission diodes , which may be formed on ge or si monocrystal substrates . ( 3 ) epitaxial ga y al 1 - y as ( 0 & lt ; y & lt ; 1 ) wafers for infrared emission diodes , red light emitting diodes and laser diodes , which may be formed on ge or gaas monocrystal substrates . ( 4 ) epitaxial ga y in 1 - y p ( 0 & lt ; y & lt ; 1 ) wafers for red emission diodes , which are formed on gap or inp monocrystal substrates . ( 5 ) epitaxial ga y in 1 - y as 1 - x p x ( 0 & lt ; y & lt ; 1 ; 0 & lt ; x & lt ; 1 ) wafers for various light emission diodes , which may be formed on gaas , gap , inas or inp monocrystal substrates .