We introduce a deep-recessed gate architecture in β-Ga2O3 delta-doped field effect transistors for improvement in DC-RF dispersion and breakdown properties. The device design incorporates an unintentionally doped β-Ga2O3 layer as the passivation dielectric. To fabricate the device, the deep-recess geometry was developed using BCl3 plasma based etching at ~5 W RIE to ensure minimal plasma damage. Etch damage incurred with plasma etching was mitigated by annealing in vacuum at temperatures above 600 degC. A gate-connected field-plate edge termination was implemented for efficient field management. Negligible surface dispersion with lower knee-walkout at high VDS, and better breakdown characteristics compared to their unpassivated counterparts were achieved. A three terminal off-state breakdown voltage of 315 V, corresponding to an average breakdown field of 2.3 MV/cm was measured. The device breakdown was limited by the field-plate/passivation edge and presents scope for further improvement. This demonstration of epitaxially passivated field effect transistors is a significant step for β-Ga2O3 technology since the structure simultaneously provides control of surface-related dispersion and excellent field management.
@article{arxiv.2004.10440,
title = {Deep-recessed $\beta$-Ga$_2$O$_3$ delta-doped field effect transistors with in situ epitaxial passivation},
author = {Chandan Joishi and Zhanbo Xia and John S. Jamison and Shahadat H. Sohel and Roberto C. Myers and Saurabh Lodha and Siddharth Rajan},
journal= {arXiv preprint arXiv:2004.10440},
year = {2020}
}