Collector breakdown in the heterojunction bipolar transistor laser

Data are presented on a quantum-well (QW)-based InGaPGaAsInGaAs (QW) heterojunction bipolar transistor laser modified with external (increased) mirror reflection yielding lower threshold current (IB =23→19 mA) and higher collector breakdown voltage (2.5 V). Increased breakdown at lower currents is observed on the collector I-V characteristics, at constant base current IB, as a slope change, a corner, and a narrow-line to broadband spectral shift from stimulated (high coherent optical field) to spontaneous (lower incoherent field) operation, a consequence of quenching or reducing photon-assisted tunneling (Franz-Keldysh effect) under the constraint IE + IB + IC =0 as α→1 (αΔ IC Δ IE).