High-performance AlGaInP tunneling heterostructure-emitter bipolar transistor

• An AlGaInP tunneling heterostructure-emitter bipolar transistor is demonstrated.
• A n-AlGaInP tunneling layer and a n-GaAs layer forms heterostructure emitter.
• The heterostructure emitter is employed to decrease collector–emitter offset voltage.
• Small hole transmission coefficient across the AlGaInP tunneling layer.
• Most of holes injecting from base will be blocked at AlGaInP/GaAs heterojunction.

In this paper, a high-performance heterostructure-emitter bipolar transistor employing an AlGaInP quaternary compound tunneling layer is fabricated and demonstrated. In the studied device, a 50 Å n-AlGaInP tunneling emitter layer together with a 200 Å n-GaAs layer forms the heterostructure emitter to decrease the collector–emitter offset voltage. On the other hand, due to the relatively large valence band discontinuity (∼0.4 eV) at AlGaInP/GaAs heterojunction and the small hole transmission coefficient across the AlGaInP tunneling layer, most of holes injecting from base to emitter will be blocked at AlGaInP/GaAs heterojunction and then high collector current and current gain are achieved. The experimental results exhibit a large collector current of 92 mA, a large current gain of 446, and a relatively low offset voltage of only 45 mV, respectively. Furthermore, a large current-gain cutoff frequency ft up to 63.7 GHz is obtained for the device with a thin tunneling layer.