Selective oxidization cavity confinement for low threshold vertical cavity transistor laser

Data are presented for a low threshold n-p-n vertical cavity transistor laser (VCTL) with improved cavity confinement by trench opening and selective oxidation. The oxide-confined VCTL with a 6.5 × 7.5 μm² oxide aperture demonstrates a threshold base current of 1.6 mA and an optical power of 150 μW at I_B = 3 mA operating at −80 °C due to the mismatch between the quantum well emission peak and the resonant cavity optical mode. The VCTL operation switching from spontaneous to coherent stimulated emission is clearly observed in optical output power L-V_CE characteristics. The collector output I_C–V_CE characteristics demonstrate the VCTL can lase in transistor's forward-active mode with a collector current gain β = 0.48.