skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.


Title: TCAD Simulation Models, Parameters, and Methodologies for β-Ga 2 O 3 Power Devices
β -Ga 2 O 3 is an emerging material and has the potential to revolutionize power electronics due to its ultra-wide-bandgap (UWBG) and lower native substrate cost compared to Silicon Carbide and Gallium Nitride. Since β -Ga 2 O 3 technology is still not mature, experimental study of β -Ga 2 O 3 is difficult and expensive. Technology-Computer-Aided Design (TCAD) is thus a cost-effective way to study the potentials and limitations of β -Ga 2 O 3 devices. In this paper, TCAD parameters calibrated to experiments are presented. They are used to perform the simulations in heterojunction p-NiO/n-Ga 2 O 3 diode, Schottky diode, and normally-off Ga 2 O 3 vertical FinFET. Besides the current-voltage (I-V) simulations, breakdown, capacitance-voltage (C-V), and short-circuit ruggedness simulations with robust setups are discussed. TCAD Sentaurus is used in the simulations but the methodologies can be applied in other simulators easily. This paves the road to performing a holistic study of β -Ga 2 O 3 devices using TCAD.  more » « less
Award ID(s):
2134374
PAR ID:
10411001
Author(s) / Creator(s):
Date Published:
Journal Name:
ECS Journal of Solid State Science and Technology
Volume:
12
Issue:
5
ISSN:
2162-8769
Page Range / eLocation ID:
055002
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. In this paper, the short circuit ruggedness of Gallium Oxide (Ga 2 O 3 ) vertical FinFET is studied using Technology Computer-Aided-Design (TCAD) simulations. Ga 2 O 3 is an emerging ultra-wide bandgap material and Ga 2 O 3 vertical FinFET can achieve the normally-off operation for high voltage applications. Ga 2 O 3 has a relatively low thermal conductivity and, thus, it is critical to explore the design space of Ga 2 O 3 vertical FinFETs to achieve an acceptable short-circuit capability for power applications. In this study, appropriate TCAD models and parameters calibrated to experimental data are used. For the first time, the breakdown voltage simulation accuracy of Ga 2 O 3 vertical FinFETs is studied systematically. It is found that a background carrier generation rate between 10 5 cm −3 s −1 and 10 12 cm −3 s −1 is required in simulation to obtain correct results. The calibrated and robust setup is then used to study the short circuit withstand time (SCWT) of an 800 V-rated Ga 2 O 3 vertical FinFET with different inter-fin architectures. It is found that, due to the high thermal resistance in Ga 2 O 3 , to achieve an SCWT >1 μ s, low gate overdrive is needed which increases R on,sp by 66% and that Ga 2 O 3 might melt before the occurrence of thermal runaway. These results provide important guidance for developing rugged Ga 2 O 3 power transistors. 
    more » « less
  2. Gallium oxide (β-Ga 2 O 3 ) is becoming a popular material for high power electronic devices due to its wide bandgap and ease of processing. In this work, β-Ga 2 O 3 substrates received various annealing treatments before atomic layer deposition of HfO 2 and subsequent fabrication of metal–oxide–semiconductor (MOS) capacitors. Annealing of β-Ga 2 O 3 with forming gas or nitrogen produced degraded capacitance–voltage (C–V) behavior compared to a β-Ga 2 O 3 control sample with no annealing. A sample annealed with pure oxygen had improved C–V characteristics relative to the control sample, with a higher maximum capacitance and smaller flat-band voltage shift, indicating that oxygen annealing improved the C–V behavior. X-ray photoelectron spectroscopy also suggested a reduction in the oxygen vacancy concentration after O 2 annealing at 450 °C, which supports the improved C–V characteristics and indicates that O 2 annealing of β-Ga 2 O 3 may lead to better MOS device performance. 
    more » « less
  3. We present a review of the published experimental and simulation radiation damage results in Ga 2 O 3 . All of the polytypes of Ga 2 O 3 are expected to show similar radiation resistance as GaN and SiC, considering their average bond strengths. However, this is not enough to explain the orders of magnitude difference of the relative resistance to radiation damage of these materials compared to GaAs and dynamic annealing of defects is much more effective in Ga 2 O 3 . It is important to examine the effect of all types of radiation, given that Ga 2 O 3 devices will potentially be deployed both in space and terrestrial applications. Octahedral gallium monovacancies are the main defects produced under most radiation conditions because of the larger cross-section for interaction compared to oxygen vacancies. Proton irradiation introduces two main paramagnetic defects in Ga 2 O 3 , which are stable at room temperature. Charge carrier removal can be explained by Fermi-level pinning far from the conduction band minimum due to gallium interstitials (Ga i ), vacancies (V Ga ), and antisites (Ga O ). One of the most important parameters to establish is the carrier removal rate for each type of radiation, since this directly impacts the current in devices such as transistors or rectifiers. When compared to the displacement damage predicted by the Stopping and Range of Ions in Matter(SRIM) code, the carrier removal rates are generally much lower and take into account the electrical nature of the defects created. With few experimental or simulation studies on single event effects (SEE) in Ga 2 O 3 , it is apparent that while other wide bandgap semiconductors like SiC and GaN are robust against displacement damage and total ionizing dose, they display significant vulnerability to single event effects at high Linear Energy Transfer (LET) and at much lower biases than expected. We have analyzed the transient response of β -Ga 2 O 3 rectifiers to heavy-ion strikes via TCAD simulations. Using field metal rings improves the breakdown voltage and biasing those rings can help control the breakdown voltage. Such biased rings help in the removal of the charge deposited by the ion strike. 
    more » « less
  4. High crystalline quality thick β-Ga 2 O 3 drift layers are essential for multi-kV vertical power devices. Low-pressure chemical vapor deposition (LPCVD) is suitable for achieving high growth rates. This paper presents a systematic study of the Schottky barrier diodes fabricated on four different Si-doped homoepitaxial β-Ga 2 O 3 thin films grown on Sn-doped (010) and (001) β-Ga 2 O 3 substrates by LPCVD with a fast growth rate varying from 13 to 21  μm/h. A higher temperature growth results in the highest reported growth rate to date. Room temperature current density–voltage data for different Schottky diodes are presented, and diode characteristics, such as ideality factor, barrier height, specific on-resistance, and breakdown voltage are studied. Temperature dependence (25–250 °C) of the ideality factor, barrier height, and specific on-resistance is also analyzed from the J–V–T characteristics of the fabricated Schottky diodes. 
    more » « less
  5. GaN-on-GaN vertical diode is a promising device for next-generation power electronics. Its breakdown voltage (BV) is limited by edge termination designs such as guard rings. The design space of guard rings is huge and it is difficult to optimize manually. In this paper, we propose an effective inverse design strategy to co-optimize BV and (V F Q) −1 , where BV, V F , and Q are the breakdown voltage, forward voltage, and reserve capacitive charge of the diode, respectively. Using rapid Technology Computer-Aided-Design (TCAD) simulations, neural network (NN), and Pareto front generation, a GaN-on-GaN diode is optimized within 24 hours. We can obtain structures with 200V higher BV at medium (V F Q) −1 or find a nearly ideal BV structure with 25% higher BV 2 /R on compared to the best randomly generated TCAD data. 
    more » « less