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Herein, the electrical and thermal performance of lateral AlGaN/GaN high electron mobility transistors (HEMTs) and metal‐insulator‐semiconductor field effect transistors (MISFETs) fabricated with 11 μm thick GaN buffer layers on 200 mm diameter Qromis Substrate Technology (QST) substrates are investigated. The QST substrate has a polycrystalline core engineered to be coefficient of thermal expansion (CTE)‐matched to GaN to minimize wafer bow and residual stress in the GaN film as a result of epitaxial growth. Raman spectroscopy is used to determine the biaxial residual stress in the GaN buffer of the as‐fabricated devices. Electrical characterization is demonstrated on the HEMTs including DC and pulsed output characteristics, DC transfer characteristics, Hall mobility, carrier concentration, sheet resistance, median transition frequency, and maximum stable gain. Finally, the thermal performance of the AlGaN/GaN MISFET is assessed via thermoreflectance thermal imaging at DC power densities up to 19 W mm−1. The thermal resistance of the MISFET, calculated using the peak temperature rises on the gate electrode for DC power densities <10 W mm−1, is measured to be 15.4 mm K W−1, which is comparable with state‐of‐the‐art GaN‐on‐Si lateral transistors. [ABSTRACT FROM AUTHOR]

AlGaN/GaN high electron mobility transistors on QST engineered substrates are grown with different GaN/AlGaN buffer layer thickness. The as‐grown heterostructures are evaluated for their structural quality via atomic force microscopy, high‐resolution X‐ray diffraction, Raman spectroscopy, and steady‐state thermoreflectance. Transistor devices are fabricated and evaluated via DC and pulsed electrical techniques, as well as thermoreflectance imaging. It is reported that buffer layer thickness of at least 10 μm can result in lateral high electron mobility transistors (HEMTs) with simultaneously high GaN quality, low stress, good DC electrical performance, low current collapse, and low thermal resistance. [ABSTRACT FROM AUTHOR]

Herein, a comprehensive model is presented for the calculation of entire current-voltage (IV) characteristics of Schottky contacts (SCs). This treatment allows to analyze in detail the physical and technological origins of empirical fit parameters like the ideality factor. This model considers variations of the semiconductor net doping density in growth direction and barrier height inhomogeneities. The only input parameters required are the doping profile, the mean value, and the standard deviation of the barrier height distribution as well as material parameters. As measuring conditions like the integration time impact measured IV characteristics, similar sweep parameters as applied during a measurement are included in the model and proven to be necessary for the understanding of charging currents and the shift of the voltage for zero current. Using this model, various nonidealities reported in literature are explained. Further, the influence of differently doped interfacial layers on the characteristics is studied. Finally, the model is applied to multiple datasets of IV characteristics of SCs on different materials published in literature and from this laboratory, enabling a fundamental understanding of the origins of the nonidealities observed as well as the distinction between the contributions of different transport mechanisms to the total current. [ABSTRACT FROM AUTHOR]

A high‐voltage AlN/GaN superlattice (SL) buffer for monolithic AlGaN/GaN power circuits is experimentally compared with a step‐graded AlGaN/GaN buffer. The SL as part of a 5.1 μm epitaxial stack withstands over 1.3 kV. Although the step‐graded buffer is sufficient for low‐side circuits, the operation voltage of monolithic topologies such as a half‐bridge is limited: static negative back gating at −200 V depletes the lateral channel completely. Asymmetrical buffer leakage at a positive substrate voltage of +250 V limits the operation voltage further. The SL buffer mitigates both effects: a negative substrate voltage of −200 V reduced the lateral channel current only by 25%. However, this condition is not required for half‐bridge operation on the SL, because low symmetrical vertical buffer leakage at substrate voltages of ±500 V allows operation of power topologies with positive substrate bias. High‐electron‐mobility transistors (HEMTs) on the graded buffer show excessive threshold voltage shift at negative substrate bias. On the SL buffer, the threshold voltage is shifted only +1 V from negative substrate biases, which allows monolithic high‐voltage power topology operation. 98.8% efficient operation of a 6 × 4 mm2 GaN‐on‐Si power integrated circuit with a monolithic half bridge, freewheeling diodes, and drivers is demonstrated on the SL. [ABSTRACT FROM AUTHOR]

In this paper the recent use AlGaN/GaN high electron mobility transistors (HEMTs) and integrated circuits on both semi‐insulating silicon carbide (SiC) and silicon substrates for radio communication in the microwave and mm‐wave frequency range is described. AlGaN/GaN monolithically microwave integrated circuits (MMICs) are extremely useful for point‐to‐point (P2P)‐links in the backbones of the 4th and upcoming 5th generation of mobile communication networks as power amplifiers, as they provide a great amount of linear power. At the same time GaN‐based power conversion electronics has driven the advancement of the growth of AlGaN/GaN heterostructures on conductive silicon (111) substrates. This again has indirectly led to advancements in the growth capabilities of AlGaN/GaN heterostructures on highly‐resistive (HR) silicon substrates. The paper gives examples of transistors and microstrip transmission‐line‐based MMICs realized in a direct comparison of GaN on s.i. SiC and GaN on HR‐silicon. Constraints and performances for highly‐efficient MMICs are discussed up to mm‐wave frequencies beyond 100 GHz. [ABSTRACT FROM AUTHOR]

We have investigated the electrical properties of Cu Schottky contacts (SCs) on ( [ABSTRACT FROM AUTHOR]

Si-doped β-Ga2O3 thin films were grown at temperatures between 400 and 650 °C and oxygen partial pressures ranging from 3 × 10−4 mbar to 2.4 × 10−2 mbar prepared by pulsed laser deposition (PLD) on c-plane sapphire substrates. For high oxygen partial pressure the samples are composed of multiple crystalline phases; for decreasing oxygen partial pressure the crystallinity improves and single phase ( [ABSTRACT FROM AUTHOR]