CdS/InP and CdS/GaAs heterojunctions by chemical-vapor deposition of CdS

CdS/InP and CdS/GaAs heterojunctions were prepared by an in situ H2S/H2 etching process and H2 transport of CdS onto the InP and GaAs substrates. The etching involves a reaction of the III-V compound surface to the corresponding sesquisulfides and simultaneous or subsequent removal by reduction in H2 gas. The etching process changes the junction characteristics considerably. The junction on p-GaAs shows a pinning of the Fermi level at the interface approximately 0.75 eV above the GaAs valence band. The junction on n-GaAs is Ohmic.