ANNEALING STABILITY AND DEVICE APPLICATION OF NONALLOYED OHMIC CONTACTS USING A LOW-TEMPERATURE-GROWN GAAS CAP ON THIN N(-LAYERS() GAAS)

This letter summarizes a study of nonalloyed ohmic contact structures consisting of Au/Ti metallization deposited on a thin (3.5 nm) layer o f low-temperature-grown GaAs (LTG:GaAs)on a thin (10 nm) layer of heav ily doped n-type GaAs. We demonstrate that this Au/Ti:LTG:GaAs/ n(+)Ga As contact structure can be used to make effective contacts to thin n( +) layers, that the resulting contact survives annealing at temperatur es between 300 degrees C and 400 degrees C, and that the contact resis tivity, rho(c), is reasonably stable for these anneals. This is contra sted with conventional Au/Ge/Ni alloyed contacts. The contact structur e has also been applied to a resonant tunneling diode (RTD). The chara cteristic current-voltage curves of RTDs show that the performance of the intrinsic barrier/well/barrier region of the device is not degrade d after anneal. (C) 1997 American Institute of Physics. [S0003-6951(97 )01943-8].