Effect of SiO2 surface passivation on the performance of GaN polarization superjunction heterojunction field effect transistors

In this article, the effects of the SiO2 surface passivation layer are reported on normally-on 1.2 kV GaN polarization superjunction (PSJ) heterojunction field effect transistors (HFETs) by comparing the electrical performances of PSJ HFETs with and without SiO2 surface passivation. A slight recovery of the 2D electron gas sheet density is observed in the slight negative shift of Vth after SiO2 surface passivation. Passivation also increases the breakdown voltage. This improvement may result from removing positive surface charges in defects along the P-GaN gate sidewall and top u-GaN layer after the specifically designed SiO2 surface passivation. Furthermore, the SiO2 surface passivation can also effectively suppress the surface gate leakage currents in the PSJ HFETs by eliminating the conductive channel created by the positive surface charges in defects

Evaluation of turn-off dV/dt controllability and switching characteristics of 1.2 kV GaN polarisation superjunction heterostructure field-effect transistors

Japanese Journal of Applied Physics The Japan Society of Applied Physics, find out more REGULAR PAPER • THE FOLLOWING ARTICLE ISOPEN ACCESS Evaluation of turn-off dV/dt controllability and switching characteristics of 1.2 kV GaN polarisation superjunction heterostructure field-effect transistors Alireza Sheikhan1, Sankara Narayanan Ekkanath Madathil1, Hiroji Kawai2, Shuichi Yagi2 and Hironobu Narui2 Published 5 July 2023 • © 2023 The Author(s). Published on behalf of The Japan Society of Applied Physics by IOP Publishing Ltd Japanese Journal of Applied Physics, Volume 62, Number 6 Citation Alireza Sheikhan et al 2023 Jpn. J. Appl. Phys. 62 064502 DOI 10.35848/1347-4065/acd975 DownloadArticle PDF Figures References Download PDF 290 Total downloads Turn on MathJax Share this article Share this content via email Share on Facebook (opens new window) Share on Twitter (opens new window) Share on Mendeley (opens new window) Hide article and author information Author e-mails [email protected] Author affiliations 1 Department of Electronic and Electrical Engineering, The University of Sheffield, Sheffield, United Kingdom 2 Powdec K.K. Oyama, Tochigi, Japan ORCID iDs Alireza Sheikhan https://orcid.org/0000-0002-2207-1593 Dates Received 16 April 2023 Revised 18 May 2023 Accepted 26 May 2023 Published 5 July 2023 Check for updates using Crossmark Buy this article in print Journal RSS Sign up for new issue notifications Create citation alert Abstract Gallium nitride (GaN) devices inherently offer many advantages over silicon power devices, including a higher operating frequency, lower on-state resistance and higher operating temperature capabilities, which can enable higher power density and more efficient power electronics. Turn-off dV/dt controllability plays a key role in determining common-mode voltage in electrical drives and traction inverter applications. The fast-switching edges of GaN can introduce challenges such as electromagnetic interference, premature insulation failure and high overshoot voltages. In this paper, the device working principle, characteristics and dV/dt controllability of 1.2 kV GaN polarisation superjunction (PSJ) heterostructure FETs (HFETs) are presented. The effect of gate driving parameters and load conditions on turn-off dV/dt are investigated. It is shown that in PSJ HFETs the dV/dt can be effectively controlled to as low as 1 kV μs−1 by controlling the gate, with a minimum increase in switching losses. These results are highly encouraging for the application of the devices in motor drives

Analysis of 1.2kV GaN polarisation superjunction diode surge current capability

Surge current capability of power diodes is one of the essential parameters that needs to be considered for high power density operations in power electronic applications. Gallium Nitride (GaN) is emerging as the next generation of power semiconductor devices due to its superior material characteristics. This work presents the device working principle, characteristics, and the surge capability of 1200V GaN polarisation superjunction (PSJ) hybrid diodes. The experimental results show that the GaN PSJ diode can withstand a surge current of 60A which is around 8 times its rated current and a surge energy of 5.4J. Additionally, despite having a merged PiN and Schottky structure, no bipolar current flow due to the activation of p-doped GaN can be observed until breakdown. This can also be confirmed through the device forward characteristic which shows a unique saturation behaviour at about 76A without any bipolar region