title: Zero-internal fields in nonpolar InGaN/GaN multi-quantum wells grown by the multi-buffer layer technique.
abstract: The potential of nonpolar a-plane InGaN/GaN multi-quantum wells (MQWs), which are free from a strong piezoelectric field, was demonstrated. An a-GaN template grown on an r-plane sapphire substrate by the multi-buffer layer technique showed high structural quality with an omega full width at half maximum value along the c-axis of 418 arcsec obtained from high-resolution x-ray diffraction analysis. From barrier analysis by deep level transient spectroscopy, it appeared that a-plane InGaN/GaN MQWs can solve the efficiency droop problem as they have a lower electron capture barrier than the c-plane sample. The peak shift of the temperature-dependent photoluminescence signal for the nonpolar InGaN/GaN MQWs was well fitted by Varshni's empirical equation with zero-internal fields. A high photoluminescence efficiency of 0.27 from this sample also showed that nonpolar MQWs can be the key factor to solve the efficiency limitation in conventional c-plane GaN based light emitting diodes.
authors.affiliation: Quantum-Function Spinics Laboratory, Department of Physics, Hanyang University, Seoul, Korea.
authors.forename: Hooyoung
authors.initials: H
authors.lastname: Song
authors.forename: Jin Soak
authors.initials: JS
authors.lastname: Kim
authors.forename: Eun Kyu
authors.initials: EK
authors.lastname: Kim
authors.forename: Yong Gon
authors.initials: YG
authors.lastname: Seo
authors.forename: Sung-Min
authors.initials: SM
authors.lastname: Hwang