Steady-State Characterization for Capture and Escape Lifetimes of 2-D Electron Gas in Light-Emitting Transistors

Quantum-well-based heterojunction bipolar light-emitting transistors (HBLETs or LETs) could work as candidate devices in optical communication and optoelectronic integrated circuits (OEICs) due to their multiport operation properties. The recombination process and capture-escape dynamics of carriers limit the device modulation bandwidth. The knowledge of capture and escape lifetimes is necessary to improve bandwidths. Here, we present a steady-state procedure rather than dynamic ones such as time-resolved photoluminescence (TRPL) or small-signal response to characterize the two lifetimes of LETs. On the experimental side, we perform dc measurements to investigate the electrical characteristics of the base–emitter (BE) junction of LETs. Theoretically, we formulate the charge-controlled model with continuity equations for electron concentrations in unbound and bound subbands of the quantum well (QW). The related capture and escape lifetimes are extracted with analytical expressions and the current gains of LETs. In the end, we verify our model by comparing the measured bandwidths to the unity gain bandwidths of this study.