Threshold investigation of oxide-confined vertical-cavity laser diodes

We report an experimental and theoretical analysis of the threshold properties of infrared oxide-confined vertical-cavity surface emitting lasers. We find good agreement between experiment and theory on the wavelength dependencies of the threshold current density and intrinsic voltage. The threshold voltage is shown to equal the sum of the calculated quasi-Fermi energy separation and the ohmic drop arising from a record low 17 to 30 Omega series resistance in these vertical-cavity lasers. Our analysis provides two independent means for determining the material threshold gain. A threshold gain of 500 cm(-1) is found for these oxide-confined lasers, which is half that estimated for ion-implanted lasers with inferior electrical and optical confinement. (C) 1996 American Institute of Physics.