@article{hou_bilbro_trew_2013, title={A Compact Physical AlGaN/GaN HFET Model}, volume={60}, ISSN={["1557-9646"]}, DOI={10.1109/ted.2012.2227323}, abstractNote={We introduce a physics-based compact model for AlGaN/GaN heterojunction field-effect transistors (HFETs) that is suitable for both RF microwave and switched-mode power supply (SMPS) applications, so that RF techniques can help determine HFET performance in SMPS applications. Such simulations can predict the on-resistance, slew rate, and breakdown voltage from the physical design of the transistor. Starting from an expression for the drain-source conduction current, charge distribution and displacement current are determined. The new model was implemented in Verilog-A and implemented in AWRDE, the design environment from Applied Wave Research. The HFET model was validated by comparison with Silvaco simulations and with data from an AlGaN/GaN HFET S-band amplifier. The new model accurately predicts device performance for dc, small-signal, and large-signal operations.}, number={2}, journal={IEEE TRANSACTIONS ON ELECTRON DEVICES}, author={Hou, Danqiong and Bilbro, Griff L. and Trew, Robert J.}, year={2013}, month={Feb}, pages={639–645} }
 @inproceedings{trew_hou_schimizzi_goswami_bilbro_2012, title={Large-signal FET Models and a New AlGaN/GaN HFET model for power amplifier design}, DOI={10.1109/icwits.2012.6417696}, abstractNote={A historical review of large-signal compact FET models is presented. Device models used in circuit design typically are based upon equivalent circuit techniques. However, it is possible to develop physics-based compact models. In this work, a new physics-based model for AlGaN/GaN HFETs that can be integrated into the commercial simulators is described. The new model has demonstrated good agreement between measured and simulated data for communications band power amplifiers.}, booktitle={2012 IEEE International Conference on Wireless Information Technology and Systems (ICWITS)}, author={Trew, R. J. and Hou, D. and Schimizzi, R. and Goswami, A. and Bilbro, G. L.}, year={2012} }
 @article{bilbro_hou_yin_trew_2009, title={Predicting the performance of a power amplifier using large-signal circuit simulations of an AlGaN/GaN HFET model}, volume={7216}, ISSN={["1996-756X"]}, DOI={10.1117/12.803348}, abstractNote={We have quantitatively modeled the conduction current and charge storage of an HFET in terms its physical dimensions and material properties. For DC or small-signal RF operation, no adjustable parameters are necessary to predict the terminal characteristics of the device. Linear performance measures such as small-signal gain and input admittance can be predicted directly from the geometric structure and material properties assumed for the device design. We have validated our model at low-frequency against experimental I-V measurements and against two-dimensional device simulations. We discuss our recent extension of our model to include a larger class of electron velocity-field curves. We also discuss the recent reformulation of our model to facilitate its implementation in commercial large-signal high-frequency circuit simulators. Large signal RF operation is more complex. First, the highest CW microwave power is fundamentally bounded by a brief, reversible channel breakdown in each RF cycle. Second, the highest experimental measurements of efficiency, power, or linearity always require harmonic load pull and possibly also harmonic source pull. Presently, our model accounts for these facts with an adjustable breakdown voltage and with adjustable load impedances and source impedances for the fundamental frequency and its harmonics. This has allowed us to validate our model for large signal RF conditions by simultaneously fitting experimental measurements of output power, gain, and power added efficiency of real devices. We show that the resulting model can be used to compare alternative device designs in terms of their large signal performance, such as their output power at 1dB gain compression or their third order intercept points. In addition, the model provides insight into new device physics features enabled by the unprecedented current and voltage levels of AlGaN/GaN HFETs, including non-ohmic resistance in the source access regions and partial depletion of the 2DEG in the drain access region.}, journal={GALLIUM NITRIDE MATERIALS AND DEVICES IV}, author={Bilbro, Griff L. and Hou, Danqiong and Yin, Hong and Trew, Robert J.}, year={2009} }
 @article{he_hou_han_2007, title={Spin-current shot noise in mesoscopic conductors}, volume={101}, number={2}, journal={Journal of Applied Physics}, author={He, Y. H. and Hou, D. Q. and Han, R. Q.}, year={2007} }
 @article{he_hou_liu_han_chen_2007, title={Time-dependent transport in low-dimensional-systems - A numerical solution using the nonequilibrium Green's functions}, volume={6}, ISSN={["1536-125X"]}, DOI={10.1109/TNANO.2006.886780}, abstractNote={In this paper, we present a novel numerical solution to analyze time-dependent transport in low-dimensional systems, such as one-dimensional (1-D) quantum dot and quasi-one-dimensional (Q1D) carbon nanotube systems, by using the nonequilibrium Green's functions (NEGF). The novelty of proposed approach is to jointly handle the NEGF in both the time-domain and the real-space-domain in a recursive fashion. The time-domain recursive approach is a straightforward approach to solve time-dependent transport problems, while the real-space recursive approach makes the calculations feasible for arbitrary-length 1-D and Q1D systems. To verify our proposed algorithm, we apply this method to explore the transient and ac transport properties of a sample 1-D quantum-dot array system. We will present in this paper the simulated electrical current curves, J (t), in response to various pulses and sinusoid waveforms. From these simulation results, we can obtain the delay and distortion information. We will then discuss how the length of a quantum-dot array and the hopping energy affect the transport behavior. The knowledge we gain from this project will help researchers to evaluate the electrical properties of 1-D and Q1D materials. The knowledge can also benefit the making of time-dependent 1-D and Q1D nanoelectronic devices}, number={1}, journal={IEEE TRANSACTIONS ON NANOTECHNOLOGY}, author={He, Yuhui and Hou, Danqiong and Liu, Xiaoyan and Han, Ruqi and Chen, Jie}, year={2007}, month={Jan}, pages={56–62} }