LOW-THRESHOLD-CURRENT AND SINGLE-MODE SURFACE-EMITTING LASER BURIED IN AMORPHOUS GAAS

We propose a vertical-cavity surface-emitting laser buried in low-temp erature-grown amorphous GaAs (a-GaAs), which was found to be effective for surface passivation of an etched cavity and suppression of high-o rder transverse modes. The deposition of highly resistive a-GaAs layer on an InGaAs/GaAs active region and AlAs/GaAs mirror layers yielded a significant improvement in threshold current density and differential quantum efficiency. The maximum currents maintaining a stable fundame ntal transverse mode were also increased by the antiguide effect of a- GaAs with a high refractive index. For a 10-mu m-diameter device, we a ttained a stable single-mode emission with a threshold current of 0.7 mA.