Electrical properties of thermally annealed p-GaAs/n-Si heterojunctions and the implications for a GaAs-Si heterojunction bipolar transistor

The electrical properties of the thermally annealed p-GaAs/n-Si heterojunction have been investigated using current-voltage and capacitance-voltage measurement techniques. Ideality factors of 1.5, built-in voltages of 1.2 V, and dramatic reductions in excess current are reported for the annealed heterojunction. Encouraged by the quality of the annealed heterointerface, the potential for actively integrating GaAs and Si in the same device was investigated. A GaAs/Si heterojunction bipolar transistor is proposed, which combines the high frequency capability of the GaAs/AlGaAs system with the advanced processing technology of Si. Using a compact transistor model, optimized fmax= 110 GHz and fmax= ft= 94 GHz are predicted for the novel device structure designed.