ELECTRON-DIFFUSION LENGTH IN INGAAS-ZN DERIVED FROM HETEROSTRUCTURE BIPOLAR-TRANSISTORS

The electron diffusion length in Zn-doped p-In0.53Ga0.47As is determin ed from the current gain in InP/InGaAs HBTs as L(n)/mu m = 9.2 x (10(1 8)/p)(0.67) for hole concentrations between p = 5 x 10(17) and 1.8 x 1 0(19) cm(-3). Epitaxial layers of different origin (MOVPE or LPE; MOVP E from different suppliers) yield the same result. These L, values agr ee with published lifetime measurements, but are larger than those mea sured by photocurrent or EBIC. Our L,, values for p-InGaAs are very si milar to those reported for p-GaAs. For HBTs, numerical expressions of the current gain as a function of base doping and base width are give n.