Deep-recessed $β$-Ga$_2$O$_3$ delta-doped field effect transistors with in situ epitaxial passivation

Chandan Joishi; Zhanbo Xia; John S. Jamison; Shahadat H. Sohel; Roberto C. Myers; Saurabh Lodha; Siddharth Rajan

doi:10.1109/TED.2020.3023679

paper

Deep-recessed $β$ -Ga $_{2}$ O $_{3}$ delta-doped field effect transistors with in situ epitaxial passivation

arXiv:2004.10440 · doi:10.1109/TED.2020.3023679

Abstract

We introduce a deep-recessed gate architecture in $β$ -Ga $_{2}$ O $_{3}$ delta-doped field effect transistors for improvement in DC-RF dispersion and breakdown properties. The device design incorporates an unintentionally doped $β$ -Ga $_{2}$ O $_{3}$ layer as the passivation dielectric. To fabricate the device, the deep-recess geometry was developed using BCl $_{3}$ 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 $°$ C. A gate-connected field-plate edge termination was implemented for efficient field management. Negligible surface dispersion with lower knee-walkout at high V $_{DS}$ , 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 $β$ -Ga $_{2}$ O $_{3}$ technology since the structure simultaneously provides control of surface-related dispersion and excellent field management.

Deep-recessed β-Ga2​O3​ delta-doped field effect transistors with in situ epitaxial passivation

Abstract

Deep-recessed $β$ -Ga $_{2}$ O $_{3}$ delta-doped field effect transistors with in situ epitaxial passivation