Chemical and semiconducting properties of NO2-activated H-terminated diamond

Progress Toward Diamond Power Field‐Effect Transistors

“…This process is referred to as surface transfer doping or activation, where the carriers are in the semiconductor and the dopants (electron‐capture species) exist in an adjacent overcoating material matrix. Adsorbed gases on the diamond surface, H 2 O with pH < 6 from atmospheric impurities, NO 2 , O 3 , and solid metal oxides (NH 4 ) 3 Ce(NO 3 ) 6 , Al 2 O 3 , WO 3 , MoO 3 , and V 2 O 5 all have demonstrated the ability to generate a diamond‐surface‐conductive layer. FETs fabricated using a combination of adsorbed NO 2 with Al 2 O 3 and Al 2 O 3 with poly‐tetra‐fluoro‐ethylene have exhibited impressive device properties with current densities from 1.2 to 1.3 A mm −1 .…”

“…Initially, it was believed that adsorbed NO 2 was taking electrons from the diamond, forming NO 2 − . However, no NO 2 − could be detected on the diamond surface, but instead NO 3 − was found at concentrations approximately equal to the positive charge density in the diamond . Given the difficulty of accurately characterizing a sub‐monolayer of adsorbed material, these results were obtained from the surface chemistry of diamond powder, <250 nm in diameter, where the surface area is increased by ≈10 4 over a diamond plate.…”

“…Details of H termination and FTIR procedures are presented in ref. . Before H‐termination, the infrared absorption peaks are consistent with the powder terminated with O and OH groups.…”

“…The powder is initially heated by the plasma to ≈1000 °C for 10 min to degas the powder and then H terminated for 60 min at ≈800 °C. Reproduced with permission . Copyright 2018, Elsevier B.V.…”

“…Fourier transform infrared absorption, FTIR, of diamond powder before (“cleaned diamond powder”) and after H‐termination.Reproduced with permission . Copyright 2018, Elsevier B.V.

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