High Performance Diamond Field-Effect Transistors on Hydrogen-Terminated Surface-Channel

Abstract

Utilizing hydrogen-terminated surface-conductive layer as channel, high performance diamond FETs are demonstrated. High frequency operations of diamond transistors have been realized. 2μm gate diamond MESFET shows f_T of 2.2GHz and f_max of 7GHz. Due to the effect of gate insulator insertion in series to source-gate capacitance of surface-channel, the source-gate capacitance of diamond MISFET is reduced by a factor of 2 as that of MESFET. The f_T and f_max of 0.7μm gate diamond MISFET reach 11 and 18GHz respectively. Analysis of diamond short channel effect is also carried out. Down to 70nm channel diamond MISFETs are realized by utilizing new FET fabrication process for gate minimization. The short channel FETs with thick gate insulator more than 25nm shows short channel effect such as drain current increase by drain biasing, positive shift of V_TH and degradation of subthreshold slope S. By the reduction of the thickness of gate insulator less than 20nm, V_TH shift and degradation of Sare suppressed.