RF performance of diamond metel-semiconductor field-effect transistor at elevated temperatures and analysis of its equivalent circuit

Temperature dependent DC and RF characteristics of p-type diamond metal-semiconductor field-effect transistors (MESFETs) on hydrogen-terminated surfaces are investigated. The device is thermally stable up to 100°C, because it does not deteriorate at all at higher temperatures. Temperature coefficients of transconductance (g_m), drain conductance (g _ds). gate-source capacitance (C_gs), gate-drain capacitance (C_gd), cut-off frequency (f_T), and maximum drain current (I_ds) were obtained from small-signal equivalent circuit analysis. The cut-off frequency (f_T) is almost totally independent of temperature. Intrinsic g_m, g_ds, and C_gs decrease with increasing temperature. C_gd is almost totally independent of temperature. The threshold voltage shifts to the negative side with increasing temperature. We propose a band model of an Al-gate contact/ H-terminated diamond to explain the temperature dependence of these components.