Spontaneous polarization effects on the optical properties of piezo-strained InGaN quantum wells

Summary form only given. Rapid development in the epitaxial growth, doping control, and device processing on group III nitride has brought in a plethora of research activity. Although much attention has been emphasized on the device application, ambiguities still exist on the emission mechanism of InGaN quantum wells (QWs). Due to the inhomogeneity issues in the material growth, it has been suggested the efficient radiative recombination of InGaN QW is due to the localized carriers at the band-tail states. Others suggest the emission is from the highly localized, quantum dot-like states in the phase-separated In-rich regions in the well. Controversy also remains on the gain and lasing mechanism of the nitride lasers. While the more traditional argument favors the mechanism of electron-hole plasma recombination originating from free carriers, some suggest the carrier localization in the plane of the QW layers can enhance the quantum efficiency. In this presentation, we show how the engineering of spontaneous polarization in the symmetric InGaN QWs can enhance the optical transition energies and emission intensity. In the high-excitation regime, the mechanism of electron-hole plasma recombination is found to dominate in the emission spectra.