Improved Optical Properties of Nonpolar AlGaN-Based Multiple Quantum Wells Emitting at 280 nm

Abstract

The optical properties of nonpolar AlGaN multiple quantum wells (MQWs) emitting at 280 nm were investigated intensively using temperature-dependent and time-resolved photoluminescence spectra associated with the characterization of structural properties. The densities of superficial pits and basal-plane stacking faults (BSFs) were reduced by 33.8% and 35.9%, respectively, for nonpolar AlGaN MQWs due to the carefully optimized dual nitridation. It was found that the nonpolar MQWs emission can be significantly improved by reducing the BSFs density as the BSFs emission was the main competing channels. Moreover, an internal quantum efficiency of 39% for nonpolar Al0.43Ga0.57N MQWs at emission wavelength of 279 nm was achieved even the full width at half maximum values of X-ray rocking curves were 0.565° for c-direction and 0.797° for m-direction. This fact means that a highly efficient deep ultraviolet light sources can be expected by means of nonpolar AlGaN due to the elimination of quantum confined Stark effect induced the decrease in radiative lifetime.

High-Performance Solar-Blind Photodetector Based on (010)-Plane β-Ga2O3 Thermally Oxidized from Nonpolar (110)-Plane GaN

“…Although AlGaN with a high Al content and MgZnO with a high Mg content are optional UWBG semiconductors to fabricate SBPDs, their application is severely limited. Because AlGaN is usually heteroepitaxially grown on a sapphire substrate, the density of defects (such as threading dislocations and cracks) associated with strain release would increase dramatically with the increased Al content. , Strong phase segregation would occur for a single wurtzite phase of MgZnO as its Mg content increases; therefore, the epitaxial growth of MgZnO with a high Mg content is challenging …”

“…Because AlGaN is usually heteroepitaxially grown on a sapphire substrate, the density of defects (such as threading dislocations and cracks) associated with strain release would increase dramatically with the increased Al content. 16,17 Strong phase segregation would occur for a single wurtzite phase of MgZnO as its Mg content increases; therefore, the epitaxial growth of MgZnO with a high Mg content is challenging. 18 For single-crystal Ga 2 O 3 , five polymorphs have been identified, designated α (corundum rhombohedral), β (monoclinic), γ (defective spiral), δ (cubic), and ε (orthorhombic or hexagonal).…”

Epitaxial Growth and Characteristics of Nonpolar a-Plane InGaN Films with Blue-Green-Red Emission and Entire In Content Range

“…[20,21] It was found that a nonpolar InGaN-based structure can eliminate QCSE, resulting in improved efficiency and a fast decay lifetime of carriers. [21,22] Nevertheless, epitaxial growth of nonpolar InGaN-based semiconductors is much more challenging than growth of polar counterparts. [23] The achievement on semipolar InGaN-based structures, such as the (11 22) plane, [24] (10 11) plane, [25] and (20 21) plane, [7,26] was reported recently due to the alleviation in growth inhibition rather than nonpolar counterpart and the weaker QCSE rather than the polar counterpart.…”