Effect of MOCVD growth conditions on the optical properties of semipolar (1(1)over-bar01) GaN on Si patterned substrates

Semipolar (1 (1) over bar 01) GaN layers were grown by metal-organic chemical vapor deposition on patterned (001) Si substrates. The effects of reactor pressure and substrate temperature on optical properties of (1 (1) over bar 01) GaN were studied by steady-state and time-resolved photoluminescence. The optical measurements revealed that the optical quality of (1 (1) over bar 01)-oriented GaN is comparable to that of c-plane GaN film grown on sapphire. Slow decay time constants, representative of the radiative recombination, for semipolar (1 (1) over bar 01) GaN grown at 200 Torr are found to be very long (similar to 1.8 ns), comparable to those for the state-of-art c-plane GaN templates grown using in situ epitaxial lateral overgrowth through silicon nitride nano-network. Defect distribution in the GaN stripes was studied by spatially resolved cathodeluminescence measurements. The c(+)-wing regions of the GaN stripes were found to be dominated by a (D-0,X) emission. Only a thin slice of emission around 3.42 eV related to basal stacking faults was revealed in c(-)-wing regions.