High Current Operation in Type-II InP/GaAsSb/InGaAs Double Heterojunction Phototransistors

The current study focuses on examining the high-current performance of InP/GaAsSb/InGaAs double heterojunction phototransistors (DHPTs) operating at a wavelength of 1.55 pm. The remarkable hole blocking property within the base, attributed to the type-II band alignment at the emitter-base and base-collector junctions, results in heightened collector photocurrent levels at reduced bias voltage and a deferred onset of the base push-out phenomenon. To mitigate base surface recombination current and augment the optical attributes of DHPTs, a passivating InP emitter-ledge layer was incorporated. This strategic application demonstrates efficacy in fortifying the phototransistors' performance char-acteristics. This study contributes valuable insights into leveraging type-II heterostructures for enhanced DHPT functionality under low-bias conditions, with implications for optoelectronic applications.