Quantum cascade emission in the Ⅲ-nitride material system designed with effective interface grading

摘要

We report the realization of quantum cascade (QC) light emission in the Ⅲ-nitride material system, designed with effective interface grading (EIG). EIG induces a continuous transition between wells and barriers in the quantum confinement, which alters the eigenstate system and even delocalizes the states with higher energy. Fully transverse-magnetic spontaneous emission is observed from the fabricated Ⅲ-nitride QC structure, with a center wavelength of ～4.9 μm and a full width at half maximum of ～110 meV, both in excellent agreement with theoretical predictions. A multi-peak photo-response spectrum is also measured from the QC structure, which again agrees well with theoretical calculations and verifies the effects of EIG.