More Like this

1. Gallium Nitride High-Electron-Mobility Transistor-Based High-Energy Particle-Detection Preamplifier

   https://doi.org/10.3390/metrology5020021  

   Orr, Gilad; Azoulay, Moshe; Golan, Gady; Burger, Arnold (June 2025, Metrology)

   GaN High-Electron-Mobility Transistors have gained some foothold in the power-electronics industry. This is due to wide frequency bandwidth and power handling. Gallium Nitride offers a wide bandgap and higher critical field strength compared to most wide-bandgap semiconductors, resulting in better radiation resistance. Theoretically, it supports higher speeds as the device dimensions could be reduced without suffering voltage breakdown. The simulation and experimental results illustrate the superior performance of the Gallium Nitride High-Electron-Mobility Transistors in an amplifying circuit. Using a spice model for commercially available Gallium Nitride High-Electron-Mobility Transistors, non-distorted output to an input signal of 200 ps was displayed. Real-world measurements underscore the fast response of the Gallium Nitride High-Electron-Mobility Transistors with its measured slew rate at approximately 3000 V/μs, a result only 17% lower than the result obtained from the simulation. This fast response, coupled with the amplifier radiation resistance, shows promise for designing improved detection and imaging circuits with long Mean Time Between Failure required, for example, by next-generation industrial-process gamma transmission-computed tomography. 

   more » « less
2. High conductivity coherently strained quantum well XHEMT heterostructures on AlN substrates with delta doping

   https://doi.org/10.1063/5.0228253  

   Chen, Yu-Hsin; Encomendero, Jimy; Savant, Chandrashekhar; Protasenko, Vladimir; Xing, Huili Grace; Jena, Debdeep (September 2024, Applied Physics Letters)

   Polarization-induced two-dimensional electron gases (2DEGs) in AlN/GaN/AlN quantum well high-electron-mobility transistors on ultrawide bandgap AlN substrates offer a promising route to advance microwave and power electronics with nitride semiconductors. The electron mobility in thin GaN quantum wells embedded in AlN is limited by high internal electric field and the presence of undesired polarization-induced two-dimensional hole gases (2DHGs). To enhance the electron mobility in such heterostructures on AlN, previous efforts have resorted to thick, relaxed GaN channels with dislocations. In this work, we introduce n-type compensation δ-doping in a coherently strained single-crystal (Xtal) AlN/GaN/AlN heterostructure to counter the 2DHG formation at the GaN/AlN interface, and simultaneously lower the internal electric field in the well. This approach yields a δ-doped XHEMT structure with a high 2DEG density of ∼3.2×1013 cm−2 and a room temperature (RT) mobility of ∼855 cm2/Vs, resulting in the lowest RT sheet resistance 226.7 Ω/□ reported to date in coherently strained AlN/GaN/AlN HEMT heterostructures on the AlN platform. 

   more » « less
3. Deep-ultraviolet transparent conducting SrSnO ₃ via heterostructure design

   https://doi.org/10.1126/sciadv.adq7892  

   Liu, Fengdeng; Yang, Zhifei; Abramovitch, David; Guo, Silu; Mkhoyan, K Andre; Bernardi, Marco; Jalan, Bharat (November 2024, Science Advances)

   Exploration and advancements in ultrawide bandgap (UWBG) semiconductors are pivotal for next-generation high-power electronics and deep-ultraviolet (DUV) optoelectronics. Here, we used a thin heterostructure design to facilitate high conductivity due to the low electron mass and relatively weak electron-phonon coupling, while the atomically thin films ensured high transparency. We used a heterostructure comprising SrSnO₃/La:SrSnO₃/GdScO₃(110), and applied electrostatic gating, which allow us to effectively separate charge carriers in SrSnO₃from dopants and achieve phonon-limited transport behavior in strain-stabilized tetragonal SrSnO₃. This led to a modulation of carrier density from 10¹⁸to 10²⁰cm⁻³, with room temperature mobilities ranging from 40 to 140 cm²V⁻¹s⁻¹. The phonon-limited mobility, calculated from first principles, closely matched experimental results, suggesting that room temperature mobility could be further increased with higher electron density. In addition, the sample exhibited 85% optical transparency at a 300-nm wavelength. These findings highlight the potential of heterostructure design for transparent UWBG semiconductor applications, especially in DUV regime. 

   more » « less
4. Tutorial: Metalorganic chemical vapor deposition of β -Ga2O3 thin films, alloys, and heterostructures

   https://doi.org/10.1063/5.0147787  

   Bhuiyan, A. F.; Feng, Zixuan; Meng, Lingyu; Zhao, Hongping (June 2023, Journal of Applied Physics)

   β-phase gallium oxide (Ga2O3) is an emerging ultrawide bandgap (UWBG) semiconductor with a bandgap energy of ∼ 4.8 eV and a predicted high critical electric field strength of ∼8 MV/cm, enabling promising applications in next generation high power electronics and deep ultraviolet optoelectronics. The advantages of Ga2O3 also stem from its availability of single crystal bulk native substrates synthesized from melt, and its well-controllable n-type doping from both bulk growth and thin film epitaxy. Among several thin film growth methods, metalorganic chemical vapor deposition (MOCVD) has been demonstrated as an enabling technology for developing high-quality epitaxy of Ga2O3 thin films, (AlxGa1−x)2O3 alloys, and heterostructures along various crystal orientations and with different phases. This tutorial summarizes the recent progresses in the epitaxial growth of β-Ga2O3 thin films via different growth methods, with a focus on the growth of Ga2O3 and its compositional alloys by MOCVD. The challenges for the epitaxial development of β-Ga2O3 are discussed, along with the opportunities of future works to enhance the state-of-the-art device performance based on this emerging UWBG semiconductor material system. 

   more » « less
5. High-Temperature Atomic Layer Deposition of GaN on 1D Nanostructures

   https://doi.org/10.3390/nano10122434  

   Austin, Aaron J.; Echeverria, Elena; Wagle, Phadindra; Mainali, Punya; Meyers, Derek; Gupta, Ashish Kumar; Sachan, Ritesh; Prassana, S.; McIlroy, David N. (December 2020, Nanomaterials)

   null (Ed.)

   Silica nanosprings (NS) were coated with gallium nitride (GaN) by high-temperature atomic layer deposition. The deposition temperature was 800 °C using trimethylgallium (TMG) as the Ga source and ammonia (NH3) as the reactive nitrogen source. The growth of GaN on silica nanosprings was compared with deposition of GaN thin films to elucidate the growth properties. The effects of buffer layers of aluminum nitride (AlN) and aluminum oxide (Al2O3) on the stoichiometry, chemical bonding, and morphology of GaN thin films were determined with X-ray photoelectron spectroscopy (XPS), high-resolution x-ray diffraction (HRXRD), and atomic force microscopy (AFM). Scanning and transmission electron microscopy of coated silica nanosprings were compared with corresponding data for the GaN thin films. As grown, GaN on NS is conformal and amorphous. Upon introducing buffer layers of Al2O3 or AlN or combinations thereof, GaN is nanocrystalline with an average crystallite size of 11.5 ± 0.5 nm. The electrical properties of the GaN coated NS depends on whether or not a buffer layer is present and the choice of the buffer layer. In addition, the IV curves of GaN coated NS and the thin films (TF) with corresponding buffer layers, or lack thereof, show similar characteristic features, which supports the conclusion that atomic layer deposition (ALD) of GaN thin films with and without buffer layers translates to 1D nanostructures. 

   more » « less