Transparent conductive metal-oxide contacts in vertical-injection top-emitting quantum well lasers

Optically transparent and electrically conductive cadmium tin oxide is employed in vertical cavity surface-emitting lasers for vertical current injection. Continuous wave lasing at room temperature is achieved in GaAs/AlGaAs quantum well lasers. Devices with a 10 μm optical window, which also serves as a vertical current injection inlet, give lasing threshold currents as low as 3.8 mA. The differential series resistance is 350–450 Ω with a diode voltage of 5.1–5.6 V at lasing threshold. Far-field pattern of the laser emission is Gaussian-like with a full width at half maximum of 7°.