Annealing stability and device application of nonalloyed ohmic contacts using a low temperature grown GaAs cap on thin n+ GaAs layers

This letter summarizes a study of nonalloyed ohmic contact structures consisting of Au/Ti metallization deposited on a thin (3.5 nm) layer of low-temperature-grown GaAs (LTG:GaAs) on a thin (10 nm) layer of heavily doped $n$ -type GaAs. We demonstrate that this Au/Ti:LTG:GaAs/$n^{+}$ GaAs contact structure can be used to make effective contacts to thin $n^{+}$ layers, that the resulting contact survives annealing at temperatures between 300 °C and 400 °C, and that the contact resistivity, ${\rho }_c,$ is reasonably stable for these anneals. This is contrasted with conventional Au/Ge/Ni alloyed contacts. The contact structure has also been applied to a resonant tunneling diode (RTD). The characteristic current-voltage curves of RTDs show that the performance of the intrinsic barrier/well/barrier region of the device is not degraded after anneal.