Achieving efficient n-type doping in AlN, a representative ultrawide bandgap (UWBG) semiconductor, remains a longstanding challenge that limits its application in high-power electronics and deep-ultraviolet optoelectronics. Conventional dopants in AlN often introduce deep levels or form compensating complexes, leading to low free-carrier concentrations. In this work, we combine first-principles defect calculations with a structural search method tailored to explore metastable configurations to systematically investigate donor-type defects in AlN. Our results reveal that the aluminum interstitial ($Al_i$) can exhibit shallow-donor behavior in specific metastable configurations that were previously overlooked. This discovery expands the understanding of n-type dopability in AlN, and highlights the critical role of metastable defects in modulating electronic properties.
Illumination and annealing characteristics of two-dimensional electron gas systems in metal-organic vapor-phase epitaxy grown AlGaN/AlN/GaN heterostructures
研究了两种不同Al组分（x=0.15和x=0.25）的AlGaN/AlN/GAN异质结的持续光电导（PPC）效应。利用Shubnikov-de Haas和Hall测量方法研究了AlN/GAN异质界面处形成的二维电子气。利用光学照射，我们能够将Al 0.15 Ga 0.85 N/AlN/GAN样品的载流子密度从1.6 × 10 ^{12} cm^{-2}增加到5.9 × 10 ^{12} cm^{-2}，同时在T = 1.6 K时电子迁移率从9540 cm 2/Vs增加到21400 cm 2/Vs。在这两个样品中的持续光电流表现出强烈的依赖于照明波长，是最高的接近带隙和降低在较长的波长。PPC效应对于长于530 nm的照明波长变得相当弱，并且在光谱的红外区域（>700 nm）中显示出具有初始负光电导的更复杂的响应。Al0.25Ga0.75N/AlN/GAN和Al0.15Ga0.85N/AlN/GAN样品在390 nm照射下的最大PPC效率分别为0.011%和0.005%。在光照后，可以通过退火样品来降低载流子密度。在20-280 K温度范围内研究了PPC效应的退火特性。我们发现，在280 K退火是不足以完全恢复的载流子密度。事实上，即使在室温下，PPC效应也发生在这些样品中。比较两种样品的测量结果，Al0.25Ga0.75N/AlN/GAN样品具有较大的光照响应，并显示出较小的恢复与…
Weak antilocalization and zero-field electron spin splitting in AlGaN/AlN/GaN heterostructures with a polarization induced two-dimensional electron gas
Ultraviolet Photodetectors based on GaN and AlGaN/AlN Nanowire Ensembles: Effects of Planarization with Hydrogen Silsesquioxane and Nanowire Architecture
研究 HSQ 包封平坦化的 GaN 与 AlGaN/AlN 纳米线紫外光电探测器，揭示其钝化、应变和偏压可调光谱响应机制，并验证器件保持单纳米线级选择性且无持续光电流。
AlGaN/AlN Stranski-Krastanov quantum dots for highly efficient electron beam pumped emitters: The role of miniaturization and composition to attain far UV-C emission
Barrier-channel intermixing and 2-dimensional electron gas degradation in Al-rich Al(Ga)N/AlGaN high electron mobility transistor heterostructures
Tyndall National Institute, University College Cork（廷德尔国家研究所，科克大学）；James Watt School of Engineering, University of Glasgow（詹姆斯·瓦特工程学院，格拉斯哥大学）；School of Physics, University College Cork（物理学院，科克大学）；School of Engineering, University College Cork（工程学院，科克大学）
Ultra-wide-band-gap group-III nitrides are of interest for applications in deep-ultraviolet optoelectronics and power electronics. Such devices must be able to efficiently dissipate heat generated from their operation, making the thermal conductivity of the constituent materials an important parameter for high-power applications. We have investigated the phonon-limited thermal conductivity of AlN, GaN, and Al$_x$Ga$_{1-x}$N using first-principles calculations, with a focus on the effects of compositional and isotopic disorder. Our Boltzmann-transport-equation calculations show that the maximum…
Demonstration of Si-doped Al-rich thin regrown Al(Ga)N films on AlN on sapphire templates with $\gt10^{15}/cm^3$ free carrier concentration using close-coupled showerhead MOCVD reactor
