Design of InGaN-ZnSnGa2N4 quantum wells for high-efficiency amber light emitting diodes

Abstract

A novel type-II InGaN-ZnSnGa2N4 quantum well (QW) structure is proposed based on recent experimental achievements for the successful epitaxy of ZnSnN2-GaN alloys and the determination of their band offsets with GaN. The simulation results indicate that this structure is promising as the active region for high-efficiency InGaN-based amber (λ ∼ 590 nm) light-emitting diodes (LEDs). The hole wavefunction in the valence band is better confined with the insertion of a monolayer scale of ZnSnGa2N4 into the InGaN QW while the electron wavefunction in the conduction band is better confined with the incorporation of an AlGaN layer in the GaN quantum barrier. The band structure of the InGaN-ZnSnGa2N4 QW is numerically simulated based on the experimentally measured band offsets between ZnSnGa2N4 and GaN. With the InGaN-ZnSnGa2N4 QW design, a low In content (20%) is required in the InGaN layer to reach a peak emission wavelength of ∼590 nm, yet an In composition of 25% is needed to reach the same emission wavelength for a conventional InGaN QW with the same layer thicknesses. Moreover, the electron-hole wavefunction overlap (Гe1−hh1) for the InGaN-ZnSnGa2N4 QW design reaches 18% for an emission wavelength at ∼590 nm. This result is much improved over the conventional InGaN QW overlap of 5% emitting at the same wavelength. The increase in electron-hole wavefunction overlap results in an approximately 14 times enhancement in the predicted spontaneous emission radiative recombination rate of the InGaN-ZnSnGa2N4 QW as compared to that of the conventional InGaN QW. This InGaN-ZnSnGa2N4 QW structure design can be promising to pave a new way to achieve high efficiency amber LEDs.