Nicholas Miller

Michigan State University | MSU · Department of Electrical and Computer Engineering

High temperature (HT) electronics applications will require the development of a broad range of devices made using different materials. Among these devices, high-electron mobility transistors (HEMTs) made with GaN and its alloys are attractive for high-power radio frequency (RF) applications. In this manuscript, we tested AlGaN/GaN HEMT devices hav...

Gallium nitride (GaN) HEMTs are a key technological component in current and next-generation RF and millimeter-wave (mm-wave) integrated circuits and subsystems. Applications where GaN has made considerable impact include radar, communications, satellite communications, and electronic warfare. A critical aspect of the RF design cycle is accurate mo...

This article presents a real-time nonlinear vector network analyzer (NVNA) testbed that enables the acquisition of the isothermal transient response of GaN HEMTs operating in pulsed class-B mode with arbitrary loads. An oscilloscope-based architecture and a cost-effective and traceable harmonic phase calibration procedure are presented for the prop...

This article presents a set of measured benchmarks for the noise and gain performance of six different millimeter-wave (mm-wave) gallium nitride (GaN) high electron mobility transistor (HEMT) technologies fabricated at four different foundries in the United States. Measurements of the GaN transistors were collected on two independent noise paramete...

We report the fabrication of N-polar GaN metal–insulator–semiconductor high-electron-mobility transistors (MIS-HEMTs) with a power-added efficiency (PAE) of 43.7% from an 8-V supply measured by load pull at 94 GHz. The devices are fabricated on 100-mm SiC substrates and exhibit excellent uniformity, constituting the first report on $W$ -band powe...

This article presents an empirical investigation of calibration effects on load-pull measurements collected on wafer and at W-band frequencies. An analysis of scattering parameter (S-parameter) measurements provides insight into how small-signal metrics germane to load pull are affected by choice of the calibration technique. It is found that off-w...

This paper reports a temperature-dependent ASM-HEMT for modeling GaN HEMTs at elevated temperatures. Modifications to the standard ASM-HEMT were developed to accurately capture the DC and RF measurements collected at varying chuck temperatures. Several results are reported which validate the model including DC-IV, pulsed-IV, scattering-parameter, a...

Various simulations of a GaN HEMT are used to study the behaviors of two different energy-transport models: the Fermi kinetics transport model and a hydrodynamics transport model as it is implemented in the device simulator Sentaurus from Synopsys. The electron transport and heat flow equations of the respective solvers are described in detail. The...

A fast and accurate deep learning (DL) based ASM-HEMT I-V model parameter extraction is presented for the first time. DL-based extraction starts with 120k training data-sets comprising of 374 million I-V data points. Training data-sets are generated through Monte Carlo simulations. The trained DL-model is demonstrated to successfully model 114 GaN...

Various simulations of a GaN HEMT are used to study the behaviors of two different energy-transport models: the Fermi kinetics transport model and a hydrodynamics transport model as it is implemented in the device simulator Sentaurus from Synopsys. The electron transport and heat flow equations of the respective solvers are described in detail. The...

We report the $W$ -band large-signal power and efficiency performance of Ga-polar graded-channel (GC) AlGaN/GaN high-electron-mobility transistors (HEMTs) with a 50-nm gate-length mini-field-plate (FP) T-gate. The pre-matched GC GaN HEMT devices with on-chip pre-matching networks show a peak power-added efficiency (PAE) of 45% at 94 GHz at 2.1 W/...

This article presents for the first time a direct connection between gate lag observed in drain current transient measurements of gallium nitride (GaN) high-electron-mobility transistors (HEMTs) and traps located in the barrier of the transistor epitaxy. Semiclassical numerical simulations are presented using the Air Force Research Laboratory’s (AF...

The path to achieving integrated RF and power conversion circuitry using the β-Ga2O3 material system is described with regard to the materials high Johnson's RF figure of merit. Recent results, including large signal data at VD = 50 V, are provided, showing progress in achieving high-voltage RF operation. Additionally, progress in achieving high-ga...

DC, small, and large signal results are shown under continuous wave and pulsed conditions for a β- Ga2O3 metal-oxide-semiconductor field-effect transistor operating at 1 and 2 GHz. The device has a maximum transducer gain, maximum output power, and peak power added efficiency of 13 dB (15 dB), 715 mW/mm (487 mW/mm), and 23.4% (21.2%), respectively...

β-Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> thin-channel MOSFETs were evaluated using both dc and pulsed I-V measurements. The reported pulsed I-V technique was used to study selfhe...

Beta phase Gallium Oxide (BGO) is an emerging ultra-wide bandgap semiconductor with disruptive potential for ultra-low power loss, high-efficiency power applications. The critical field strength is the key enabling material parameter of BGO which allows sub-micrometer lateral transistor geometry. This property combined with ion-implantation technol...

A detailed description and analysis of the Fermi kinetics transport (FKT) equations for simulating charge transport in semiconductor devices is presented. The fully coupled nonlinear discrete FKT equations are elaborated, as well as solution methods and work-flow for the simulation of RF electronic devices under large-signal conditions. The importa...

A promising time domain electromagnetics numerical method for treating the highly nonlinear problem of charge transport in electronic devices called Delaunay–Voronoi surface integration is presented. This method couples the rotational electric and magnetic fields governed by Ampere's and Faraday's laws with the electrostatic potential dictated by P...

A nodal Discontinuous Galerkin (DG) method is derived for the analysis of time-domain (TD) scattering from doubly periodic PEC/dielectric structures under oblique interrogation. Field transformations are employed to elaborate a formalism that is free from any issues with causality that are common when applying spatial periodic boundary conditions s...

Cavity mediated energy transfer is vital to numerous technologies, such as systems that harvest/generate light, quantum information, and platforms for studying strongly coupled cavity QED. In these processes, the density of photonic states through which a donor and acceptor complex exchange energy is dramatically modified by a resonant structure su...

The analysis of fields in periodic dielectric structures arise in numerous applications of recent interest, ranging from photonic bandgap structures and plasmonically active nanostructures to metamaterials. To achieve an accurate representation of the fields in these structures using numerical methods, dense spatial discretization is required. This...