Spectral response of Au–Ti Schottky barrier on semi‐insulating GaAs

For the fabrication of the rectifying contact, respectively the Schottky diode structure on semi‐insulating GaAs (100) oriented, Cr‐doped, with a resistivity of ρ ∼ 10 6 –10 7 Ω cm we have used Au–Ti contact. The Ti contact was deposited on a plasma etched GaAs surface in high vacuum (10 –8 torr), Au was deposited in medium vacuum (10 –6 torr) and the Au–Ti/GaAs interface was formed by a rapid thermal annealing procedure at T = 320 – 360 °C in low vacuum (10 –1 torr). The representative I – V characteristics in dark and under illumination at different power levels are presented. It is worth to mention that we estimate a barrier height of Φ B ∼ 0.84 V (in the frame of thermionic emission model). The spectral response at two operating points and at different temperatures is presented. The signal has a maximum in the Δ λ range (850–950) nm, which corresponds to the generation of photo‐carriers due to a band‐to‐band direct transition. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)