Hot Electron Effect in Short n+nn+ GaAs

Current-voltage characteristics are measured by applying pulse voltages in short n+nn+ GaAs with a channel length of 1 µm. The observed non-ohmic behavior is interpreted in terms of the hot electron effect, the analysis being made by taking into account the non-uniform electric field distribution due to the boundary conditions of the short semiconductors. The results reveal that the dependence of the electron mobility on the electric field is not simple as in n-Si, but is complicated by the transfer of hot electrons to the higher-lying conduction valleys. The analysis gives the spatial distribution of the electron drift velocity, indicating the existence of drift velocity overshoot. The observed maximum drift velocity is about 3.2×107cm/s.