Bidirectional bistability in n-p-n Si/Si/sub 1-x/Ge/sub x//Si structures

Several structures of n-Si/p-Si/sub 1-x/Ge/sub x//n-Si double heterojunction bipolar transistors (DHBTs) with strained thin base, fabricated by molecular beam epitaxy (MBE), are described. Negative differential resistance (NDR) phenomena-a strong and symmetric bidirectional bistability modulated by base bias, together with a multistep characteristic in collector current versus emitter-collector bias voltage in the devices with very thin base-were observed at room temperature. The physical origins are analyzed. The results are compared with the characteristics of n-Ga/sub 1-x/A1/sub x/As/p-GaAs/n-GaAs single HBTs (SHBTs).<
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