Electronic and Optoelectronic Characterization of Au Schottky Barrier Contacts on MOCVD grown (1) GaAs/Ge, (2) GaAs/Ge/Si and (3) GaAs/Si

Recently there has been strong interest in epitaxial growth of GaAs on Si and characterization of its material properties. However, very little work has been done in comparing GaAs grown on different substrate structures. An experimental study has been performed on the electronic and optoelectronic properties of rectifying Au Schottky Barrier contacts on MOCVD grown GaAs (1) on bulk Ge, (2) on Si coated with Ge and (3) directly on Si. 

The electrical properties were studied by current vs. voltage (I-V) and capitance vs. voltage (C-V) measurement. Their photoresponse was tested with 0.87 um and 1.3 um laser diodes. The results indicate that the GaAs/Ge structure has excellent I-V characteristic with ideality (n) factor very close to unity in the forward region and good saturation characteristic in the reverse region. Dark current as low as 30 nA was observed ar -5v. Barrier height (0B) is about 0.825 eV as deduced by I-V measurements ans is in good agreement with C-V measurements. Doping density is 3.225E16 cm-3 uniform to 0.65 um.