invention in a plasma enhanced cvd process using plate as an example in fig2 deposition chamber 1 is evacuated to a prevacuum of 10 torr wherein cathode 2 is expressed as while anode 3 is expressed as and the power source is expressed as 5 6 expresses metallic mesh screen 7 34 u2190 34 expresses the direction of the gas flow preparation of layer 101 sih 4 h 2 and nh 3 or ch 4 gases are premixed and introduced into the deposition chamber the ratio of nh 3 or ch 4 gas flow rate to sih gas flow rate is 5 7 volume ratio layer 101 can be optionally used preparation of layer 102 sih 4 h 2 and b 2 h 6 gases are premixed and introduced into the deposition chamber the ratio of b 2 h 6 gas flow rate and sih 4 gas flow rate is less than 5 u00d7 10 5 atomic ratio preparation of layer 103 nh 3 or ch 4 and sih 4 gases are premixed and introduced into the deposition chamber the ratio of nh 3 or ch 4 sih 4 volume ratio varies continuously from that of the gas composition of the transport layer 104 to zero preparation of layer 104 sih 4 h 2 and nh 3 or ch 4 gases are premixed and introduced into the deposition chamber the ratio of nh 3 or ch 4 sih 4 is 3 10 volume ratio all functional layers are deposited on al substrate 4 which is attached to the cathode 2 in the rf plasma discharge deposition chamber layer 104 is deposited by.