Fast-response photodiode based on a surface-barrier $Au-nn^+-GaAs$ structure

A fast-response photodiode was constructed from a surface-barrier $Au-nn^+-GaAs$ structure. The active $n$-type region was a film grown by vapor epitaxy and characterized by a free-electron density $n=10^{14}-10^{15}$ cm${}^{-3}$. The photodiode was highly sensitive in a wide spectral range of 0.25-0.9$\mu m$. The monochromatic current responsivity was 0.5 A/W at $\lambda=0,8\mu m$. The rise time of the photoresponse signal was 100 psec when the bias voltage was up to 50 V.