Abnormal Bias-Temperature Stress and Thermal Instability of <inline-formula> <tex-math notation="LaTeX">$\beta$ </tex-math></inline-formula>-Ga₂O₃ Nanomembrane Field-Effect Transistor

Abstract

In this paper, we report on the electrical and thermal instability of β-Ga2O3 nanomembrane field-effect transistor with a bottom-gate configuration. The fabricated device exhibits high electrical performance of field-effect mobility of up to 60.9 cm2/V·s, on/off-current ratio of 109 and subthreshold slope of 210 mV/dec. However, we observe abnormal positive threshold voltage (VTH) shifts under negative bias-temperature stress at an elevated operating temperature of 80 °C as well as under temperature-dependent transfer characteristics up to 200 °C. This abnormal instability is significantly influenced by the surface depletion effect, and is discussed using energy band diagram. The opposite VTH shift was achieved by applying atomic-layer deposited Al2O3 passivation layer.

Keywords

• β-Ga₂O₃
• bias stress
• stability