Nonpolar growth and characterization of a-plane InGaN/GaN quantum well structures with different indium compositions

Characteristics of nonpolar (11–20) a-plane GaN template on r-plane sapphire substrate and subsequently grown InGaN/GaN quantum well (QW) structures were investigated. The crystal orientation and the defect evolution behavior in a-plane GaN template were confirmed by using selected area diffraction and transmittance electron microscopy. The values of full width at half maximum (FWHM) of (11–20) X-ray rocking curves along the c- and m-directions were 415 and 595arcsec respectively. The optical characteristics of a-plane InGaN/GaN QW samples with different indium compositions were intensively studied by using temperature-dependent photoluminescence (PL) spectra. The thermal activation energy for localized states increased from 26.5 to 41meV with increase of indium compositions. Also their relative PL efficiencies and FWHM values showed a potential for nonpolar-based light emitters.