ORIGINAL PAPER A Numerical Investigation of Heat Suppression in HEMT for Power Electronics Application L. Arivazhagan 1 & D. Nirmal 1 & P. Pavan Kumar Reddy 1 & J. Ajayan 2 & D. Godfrey 1 & P. Prajoon 3 & Ashok Ray 4 Received: 2 June 2020 /Accepted: 10 August 2020 # Springer Nature B.V. 2020 Abstract In this paper, AlGaN/GaN High Electron Mobility Transistor (HEMT) with stacked passivation (Diamond/SiN) is proposed and investigated. The implementation of stacked passivation in HEMT has been shown to be effective in suppressing self-heating effect. Under the gate-terminal, the peak channel temperature of HEMT with stacked passivation is 384 K, whereas it is 393 K for conventional HEMT. The reduction of channel temperature in the proposed device is attributed to good heat-spreading via diamond. The thermal resistance (R TH ) is extracted and it is found that R TH of proposed HEMT is 17% lower than that of the conventional HEMT. The transconductance of the proposed GaN-HEMT is also improved by 12%. Furthermore, the maximum drain current of 800 mA/mm at V GS = 0 V and V DS = 5 V is obtained for the proposed HEMT with a gate length of 0.25 μm. The proposed device is considered as one of the most attractive candidates for future high frequency and high-power applications over a wide range of operating temperatures. Keywords GaN . HEMT . Self-heating . Diamond . Therma resistance 1 Introduction In recent years, AlGaN/GaN-on-SiC HEMT receives a great attention in power amplifier and power switches due to their capability of delivering high power at high-frequency [1–3]. Technology innovations such as field plate engineering, back- barrier under GaN buffer and gate-length reduction further enhances the RF and DC performance of GaN HEMT. The performance metrics are breakdown voltage [4–6], drain cur- rent [7–9], output-power [10–13], unity current-gain cut-off frequency (f T )[14], maximum oscillation frequency (f MAX ) etc. However, the improvement in these performance metrics increase the acceleration/velocity of electron in the channel under gate edge of the device. This results in increase of ther- mal resistance, reduction of total safe operating area, and increase of channel temperature in the device [15]. Thermal failure and threshold failure levels in semiconductor device also occurs due to increased channel temperature. The in- crease in channel temperature results in self-heating effects which is a serious concern in modern AlGaN/GaN HEMT and an extensive investigation is required in this case. A con- tinuous effort has been made to model and/or characterize the self-heating effect and thermal resistance [15, 16]. Very few efforts have been taken to reduce channel-temperature and thermal resistance in the device. Hence, there is a great space in optimising device layout and choice of epitaxial layers for AlGaN/GaN HEMT towards the suppression of self-heating effects. In this paper, AlGaN/GaN HEMT with optimized passivation dielectric is proposed to suppress the device heating and thermal resistance. In passivating the GaN HEMT by dielectric material, the Silicon Nitride (SiN) is the most popular choice over the other dielectric materials [17–27]. It is due to the fact that SiN establishes a good quality interface (less dangling bond or surface traps) with GaN or AlGaN layer and thereby reduces the leakage current in the device [23, 28–30]. The SiN dielectric not only reduces the leakage current, but also helps to suppress the current collapse in GaN HEMTs. Thus, the complete elimination of SiN is not an effective technique in optimizing the passivation dielectric. As a compromise, the combination of Diamond and SiN * D. Nirmal nirmal@karunya.edu 1 Karunya Institute of Technology and Sciences, Coimbatore, India 2 SNS College of Technology College in Coimbatore, Coimbatore, India 3 Jyothi Engineering College, Cheruthuruthy, Thrissur, India 4 Indian Institute of Technology, Guwahati, India Silicon https://doi.org/10.1007/s12633-020-00647-3