8×8 vertical-cavity surface-emitting laser array using oxide surface barrier

We have demonstrated that an exposed AlAs layer can be sealed against further wet oxidation and an 8×8 vertical-cavity surface-emitting laser (VCSEL) array was fabricated using the sealing technique. A critical processing step consists of the formation of an oxide surface barrier by the first wet oxidation for a short time at 390-430 °C in steam environment of previously room ambient exposed AlAs surface. The best optimum condition for sealing AlAs was to form the oxide surface barrier with a thickness of ∼1 μm at 408 °C for 15 s. Then the buried AlAs layers were protected against further wet oxidation at 400 °C for one hour. The threshold current of an 8 × 8 VCSEL array ranged from 0.2 to 1.5 mA. This laser array had an average threshold current of 0.46 mA and a standard deviation of 0.26 mA. The thermal resistance of an element of the array was about 1.82 °C/mW.