Frequency Response Analysis of a Uni-traveling-carrier Double Hetero-junction Phototransistor(Invited Paper)

To relieve the contradiction between phototransistor response and its working speed, the influences of photo-generated carriers in UTC-DHPT on the junction capacitances of emitter junction and collector junction were discussed in detail and then the high frequency modeling of UTC-DHPT was built in this paper. Based on the proposed modeling, the optical gain and optical characteristic frequency of UTC-DHPT were analyzed under three different working modes, namely DHBT working mode, 2T two-terminal working mode with only optical base biasing and 3 T three-terminal working mode with hybrid optical and electrical base biasing. The results show that UTC-DHPT have better frequency response than traditional SHPT, and UTC-DHPT can provide high responsivity and high response speed simultaneously at 3T working mode.