Impact of V/III flux ratio and Si-doping concentration on GaN grown by metalorganic chemical-vapor deposition on sapphire substrate

The impact of growth regime on surface morphology, crystalline structural and electrical properties of n-type GaN using metalorganic chemical-vapor deposition (MOCVD), with intentional Si doping (SiH/sub 4/, 50.0 ppm) levels ranging from 2.5 sccm to 22.0 sccm (electron concentration varying from 1.46/spl times/10/sup 17/ to 1.07/spl times/10/sup 19/ cm/sup -3/) and V/III flux ratio from 1250 to 2800 (i.e. from Ga-rich regime to N-rich regime), are investigated. It has been found out that the V/III flux ratio affects the incorporation of Ga and N atoms into the film, and the screw dislocation generation. As for Si-incorporation, it increases the surface roughness and changes the edge dislocation generation. In this experiment, it shows clearly that those samples with V/III flux ratio of /spl sim/1500 which is close to the equilibrium condition exhibit the best properties.