High optical gain InGaN/GaN MQW electroluminescent heterostructures grown on silicon by MOCVD

Laser properties of InGaN/GaN MQW electroluminescent heterostructures grown on silicon substrates were investigated. The laser threshold increases with the cavity length reduction from 75 kW/cm² (990 mum) to 1180 kW/cm² (176 mum) under optical pumping of the GaN:Mg cap layer of the heterostructures at room temperature. The optical confinement factor, the absorption loss in the silicon substrate, the cavity edges reflection and the far field emission intensity distribution were calculated in dependence on the transversal mode order. It was shown that laser action occurs on the first order transversal mode. Optical gain value of the heterostructure was evaluated from the laser threshold dependence on the cavity length. It was equal to 22 cm^-1 at 75 kW/cm² and reached 100 cm^-1 at 1200 kW/cm². The optical material gain value of InGaN was assessed to be 2500 cm^-1 at 75 kW/cm² and 11000 cm^-1 at 1200 kW/cm², at that the laser wavelength at gain maximum reduced from 433 nm to 425 nm.