Growth, optical, and electron transport studies across isotype n-GaAs/n-Geheterojunctions

A diode structure consisting of a polar epilayer on a nonpolar substrate gr own by metalorganic vapor phase epitaxy often faces problems of antiphase d omain formation in the polar semiconductor and cross diffusion across the h eterointerface. Ge outdiffusion into GaAs epilayers was studied by low temp erature photoluminescence spectroscopy after etching the film from the surf ace. The absence of p-n junction formation inside the Ge substrate from int erdiffusion of Ga and As has been studied by current-voltage characteristic s using mesa diodes. These observations were confirmed by electrochemical c apacitance voltage polaron profiler and secondary ion mass spectroscopy tec hniques. To understand the material quality and current conduction mechanis m across the GaAs/Ge heterojunction, I-V characteristics of Si-doped n-GaAs /n-Ge isotype heterojunctions using Au Schottky diodes have been studied fo r different doping densities. A plethora of growth conditions appear in the literature concerning the attempt to grow antiphase domain (APD)-free GaAs on Ge. In the present case, even though the growth temperature regime is c lose to reported values, the main difference in minimizing APD formation ma y arise from the growth rates (similar to 3 mu m/h) and the V/III ratio (si milar to 88). (C) 1999 American Vacuum Society.