Microwave Determination of Quantum-Well Capture and Escape Time in Light-Emitting Transistors

We report the determination of In_0.20Ga_0.80As quantum-well (QW) capture and escape time by utilizing electrical microwave measurement on an InGaP/GaAs light-emitting transistor (LET) platform. The emitter-to-collector transit times τ_ec of the LET and the heterojunction bipolar transistor (HBT) are measured and extracted under the same bias condition (V_bc = 0 V and J_c = 22.6 kA/cm²). Small-signal model analysis shows that the LET exhibits a larger base transit time τ_t of 25 ps compared with 5 ps of the HBT. The difference, i.e., 20 ps, hence is attributed to the carrier capturing/escaping processes caused by the QWs embedded in the base region of the LET.