DC conduction and low-frequency noise characteristics ofGaAlAs/GaAs single heterojunction bipolar transistors at roomtemperature and low temperatures

The DC conduction and low-frequency noise characteristics of GaAlAs/GaAs single heterojunction bipolar transistors (HBTs) have been investigated at room temperature and at temperatures down to 5 K. The collector current dependence of the current gain was investigated at various temperatures. The low-frequency noise characteristics exhibit both 1/f and generation-recombination components. The noise characteristics are sensitive to changes in base current and insensitive to changes in collector-emitter voltage, thus suggesting that the noise source is located in the vicinity of the emitter-base heterojunction. The noise spectrum follows a simple model based on minority carrier trapping effects at the heterointerface