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 on GaAs (001) substrates. The device performance and crystal quality were investigated. The emission wavelength was controlled by the In content in the cubic InGaN active layer. The violet-blue electroluminescence was observed around 435 nm with a FWHM of 55 nm from a cubic In_0.07Ga_0.93N/GaN DH LED. The 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 investigate the phase purity and strain in InGaN/GaN heterostructure. The mixing of the stable hexagonal phase in the cubic GaN was observed and the hexagonal phase content was about 10%. In-situ spectroscopic ellipsometry measurement showed that most of the mixed hexagonal domains were likely to be formed in the Mg-doped GaN layer. In addition, the anisotropic lattice relaxation occurred in the InGaN active layer. The elimination of the hexagonal phase inclusions plays an important role for the realization of high performance devices.