Cubic InGaN/GaN double-heterostructure light emitting diodes grown on GaAs(001) substrates by MOVPE

Cubic (zinc-blende) InGaN/GaN double-heterostructure LEDs were fabricated o n GaAs (001) substrates. The device performance and crystal quality were in vestigated. The emission wavelength was controlled by the In content in the cubic InGaN active layer. The violet-blue electroluminesence was observed around 435 nm with a FWHM of 55 nm from a cubic In0.07Ga0.93N/GaN DH LED. T he forward voltage was 4.9 V at 20 mA and the reverse leakage current was 5 mA at -10 V. X-ray reciprocal space mapping measurement was performed to i nvestigate the phase purity and strain in InGaN/GaN heterostructure. The mi xing of the stable hexagonal phase in the cubic GaN was observed and the he xagonal phase content was about 10%. In-situ spectroscopic ellipsometry mea surement showed that most of the mixed hexagonal domains were likely to be formed in the Mg-doped GaN layer. In addition, the anisotropic lattice rela xation occurred in the InGaN active layer. The elimination of the hexagonal phase inclusions plays an important role for the realization of high perfo rmance devices.