GaN/AlGaN multiple quantum wells grown on transparent and conductive (-201)-oriented β-Ga2O3 substrate for UV vertical light emitting devices

GaN/AlGaN multiple quantum wells (MQWs) are grown on a 2 ¯ 01-oriented β-Ga2O3 substrate. The optical and structural characteristics of the MQW structure are compared with those of a similar structure grown on sapphire. Scanning transmission electron microscopy and atomic force microscopy images show that the MQW structure exhibits higher crystalline quality of well-defined quantum wells when compared to a similar structure grown on sapphire. X-ray diffraction rocking curve and photoluminescence excitation analyses confirm the lower density of dislocation defects in the sample grown on a β-Ga2O3 substrate. A detailed analysis of time-integrated and time-resolved photoluminescence measurements shows that the MQWs grown on a β-Ga2O3 substrate are of higher optical quality. Our work indicates that the 2 ¯ 01-oriented β-Ga2O3 substrate can be a potential candidate for UV vertical emitting devices

Manipulation of hot carrier cooling dynamics in two-dimensional Dion–Jacobson hybrid perovskites via Rashba band splitting

Hot-carrier cooling processes of perovskite materials are typically described by a single parabolic band model that includes the effects of carrier-phonon scattering, hot phonon bottleneck, and Auger heating. However, little is known (if anything) about the cooling processes in which the spin-degenerate parabolic band splits into two spin-polarized bands, i.e., the Rashba band splitting effect. Here, we investigated the hot-carrier cooling processes for two slightly different compositions of two-dimensional Dion–Jacobson hybrid perovskites, namely, (3AMP)PbI4 and (4AMP)PbI4 (3AMP = 3-(aminomethyl)piperidinium; 4AMP = 4-(aminomethyl)piperidinium), using a combination of ultrafast transient absorption spectroscopy and first-principles calculations. In (4AMP)PbI4, upon Rashba band splitting, the spin-dependent scattering of hot electrons is responsible for accelerating hot-carrier cooling at longer delays. Importantly, the hot-carrier cooling of (4AMP)PbI4 can be extended by manipulating the spin state of the hot carriers. Our findings suggest a new approach for prolonging hot-carrier cooling in hybrid perovskites, which is conducive to further improving the performance of hot-carrier-based optoelectronic and spintronic devices. © 2021, The Author(s).Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]