Design of InGaN-ZnSnN2 quantum wells for high-efficiency amber light emitting diodes

Abstract

InGaN-ZnSnN2 based quantum wells (QWs) structure is proposed and studied as an active region for high efficiency amber (λ ∼ 600 nm) light emitting diodes (LEDs), which remains a great challenge in pure InGaN based LEDs. In the proposed InGaN-ZnSnN2 QW heterostructure, the thin ZnSnN2 layer serves as a confinement layer for the hole wavefunction utilizing the large band offset at the InGaN-ZnSnN2 interface in the valence band. The barrier layer is composed of GaN or AlGaN/GaN in which the thin AlGaN layer is used for a better confinement of the electron wavefunction in the conduction band. Utilizing the properties of band offsets between ZnSnN2 and InGaN, the design of InGaN-ZnSnN2 QW allows us to use much lower In-content (∼10%) to reach peak emission wavelength at 600 nm, which is unachievable in conventional InGaN QW LEDs. Furthermore, the electron-hole wavefunction overlap (Γe-h) for the InGaN-ZnSnN2 QW design is significantly increased to 60% vs. 8% from that of the conventional InGaN QW emitting at the same wavelength. The tremendous enhancement in electron-hole wavefunction overlap results in ∼225× increase in the spontaneous emission radiative recombination rate of the proposed QW as compared to that of the conventional one using much higher In-content. The InGaN-ZnSnN2 QW structure design provides a promising route to achieve high efficiency amber LEDs.