Photocurrent spectra of semi-insulating GaAs M–S–M diodes: Role of the contacts


Current–voltage characteristics and photocurrent spectra (600–1000 nm) of semi-insulating GaAs structures with different semitransparent top contacts (AuGeNi, Pt, Gd and Nd) were measured. Obtained results, especially the presence of photocurrent peak near 890 nm and the change of photocurrent sign have been explained by considering both GaAs bulk properties and photovoltaic effects on top and bottom contacts modelled as Schottky-like barriers.

Photocurrent spectrum in SI GaAs
Spectral dependence of normalized photocurrent under short-circuit (0 V) conditions for the sample with Pt top (illuminated) metallization – comparison of experimental (red) and fitting model (black) curves. The experimental photocurrent spectrum is corrected for the constant photon flux.