nonselective rpcvd process of single crystal silicon germanium in particular features and components 102 104 106 107 108 112 114 115 and 116 of structure 100 of fig1 are shown respectively as features and components 402 404 406 407 408 412 414 415 and 416 of structure 400 of fig4 in addition etch stop layer 317 and cap layer 318 of structure 360 of fig3 b are shown respectively in structure 400 of fig4 as etch stop layer 417 and cap layer 418 thus fig4 shows structure 400 subsequent to step 260 of flow chart 200 and after epitaxial deposition in a nonselective rpcvd process of single crystal silicon germanium base 421 of the npn hbt on top surface 404 of collector 402 because the epitaxial deposition of silicon germanium is nonselective structure 400 also shows the deposition of polycrystalline base contact 422 having interface 423 with base 421 polycrystalline base contact 422 is deposited above cap layer 418 etch stop layer 417 and field oxide isolation regions 414 and 415 fig4 shows structure 400 after epitaxial deposition in an rpcvd process of single crystal silicon germanium base of the npn hbt as discussed above the higher gain speeds and frequency response of the hbt have been achieved as a result of certain advantages of silicon germanium not available with pure silicon for example the higher speeds and frequency response of the hbt have been achieved as a result of taking advantage of the.