Data (300 and 77 K) are presented on the photopumped laser operation of AlxGa1−xAs–GaAs vertical cavity quantum well heterostructure crystals that exhibit enhanced hot‐carrier recombination. The mirrors defining the vertical cavity are formed by selective lateral oxidation (H2O+N2, 425 °C, 30 min) of quadruple AlAs layers separated by lower composition AlxGa1−xAs ‘‘stop’’ layers in order to create upper and lower high‐index‐step oxide‐semiconductor distributed Bragg reflector mirrors. The Q of the compact vertical‐cavity (a microcavity) enhances the spontaneous and stimulated recombination of hot carriers, making possible single mode laser operation at an energy corresponding to the second state of the quantum well. The laser operation can be shifted to the first state by cooling to 77 K and shifting the energy gap towards the vertical cavity resonance. ©1995 American Institute of Physics.