Fabrication of Metal-Oxide-Diamond Field-Effect Transistors with Submicron-Sized Gate Length on Boron-Doped (111) H-Terminated Surfaces Using Electron Beam Evaporated SiO_(2) and Al_(2)O_(3)

摘要

A H-terminated surface conductive layer of B-doped diamond on a (111) surface was used to fabricate a metal-oxide-semiconductor field-effect transistor (MOSFET) using an electron beam evaporated SiO_(2) or Al_(2)O_(3) gate insulator and a Cu-metal stacked gate. When the bulk carrier concentration was approximately 10~(15)/cm~(3) and the B-doped diamond layer was 1.5 (mu)m thick, the surface carrier mobility of the H-terminated surface on the (111) diamond before FET processing was 35 cm~(2)/Vs and the surface carrier concentration was 1.5 X 10~(13)/cm~(2). For the SiO_(2) gate (0.76 (mu)m long and 50 (mu)m wide), the maximum measured drain current at a gate voltage of -3.0 V was -75 mA/mm and the maximum transconductance was 24 mS/mm, and for the Al_(2)O_(3) gate (0.64 (mu)m long and 50 (mu)m wide), these features were -86 mA/mm and 15 mS/mm, respectively. These values are among the highest reported direct-current (DC) characteristics for a diamond homoepitaxial (111) MOSFET.