A reduction of the threshold current density of InGaN quantum well (QW) lasers is found from the usage of AlGaInN barriers. Large bandgap and strain-managing AlGaInN barriers surrounding the InGaN quantum wells’ (QWs) active regions are investigated via the 6-band self-consistent k·p formalism for their spontaneous emission, material gain, and threshold current density properties. In this study, quaternary AlGaInN alloys both lattice-matched and tensile-strained to GaN, with bandgaps ranging from 3.4 eV to 5.2 eV, are employed as thin barriers (∼1 nm) surrounding the InGaN active region. The AlGaInN barriers provide strong carrier confinement, which improves the electron and hole wavefunction overlap by ∼25%, while simultaneously reducing the strain relaxation in the active region. This study shows that InGaN QWs surrounded by AlGaInN barriers improve the material gain by ∼30%, reduce the threshold carrier density by ∼18%, and reduce the threshold current density by ∼40% over the conventional InGaN/GaN QW structure. Our results indicate that the AlGaInN barriers substantially enhance the radiative efficiency and reduce the power consumption for light emitting diodes (LEDs) and laser diodes (LDs), making them very attractive candidates for the design of low threshold optoelectronic devices.

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We propose a type-II AlInN/ZnGeN2 quantum well (QW) structure serving as the active region for ultraviolet (UV) laser diodes. A remarkably low threshold current density can be achieved using the type-II AlInN/ZnGeN2 QW structure, providing a pathway for the realization of electrically-driven nitride-based semiconductor UV laser diodes. ZnGeN2 has both a very similar lattice constant and bandgap to GaN. Its large band offsets with GaN enable the potential of serving as a hole confinement layer to increase the electron-hole wavefunction overlap in the active region. In this study, we investigate the spontaneous emission and gain properties of type-II AlInN/ZnGeN2 QWs with different ZnGeN2 layer thicknesses. Our findings show that the use of ZnGeN2 layers in the active region provides a significant improvement in hole carrier confinement, which results in ∼5 times enhancement of the electron-hole wave function overlap. Such an enhancement provides the ability to achieve a significant increase (∼6 times) in the spontaneous emission rate and material gain, along with a remarkable reduction in threshold carrier density compared to the conventional AlGaN-based QW design, which is essential for practical UV laser diodes.