High current drive InP/InGaAs/InP DHBT with a composite step-graded collector

摘要

InPICSC23P.DOC/InGaAs/InP DHBT with a composite ste--graded INGaAsP collector has been optimised by means of two-dimensional numerical simulations for high current drive. A collector current ensity as high as 9.8x10~5 A/cm~2 could be expected from ICSC23P.DOCthe following composite step-graded collector: a 100A n-InGaAs layer adjacent to the P~+-InGaAs base; following by three 200A n-INGaAsP layers: a 100a, n chemical bounds 3x10~(17) cm~(-3) InP layer and the ests n~-InP. The bandgap of the InGaAsP layers must be chosen to render approximately equal band offset ( DELTA E_C) at the heterointerfaces. The presence of the n~--INGaAs layer and the moderately doped n-InP layer in the otherwise n~--collector have been ascertained to be essential to acieving high current drive.