Diamond electronics: Surface chemical control and characterization*

As an electronic material system diamond is maturing towards realizing the extreme device performance for which it is fundamentally suited. In parallel, the creation of diamond electronic devices has shown significant progress recently, both for surface-fashioned and bulk-doped architectures. In this talk I will present our efforts to mature our understanding of the device surface, identify surface defects and expand the toolbox of surface termination chemistries and processing techniques.

Specifically, I will detail our maturing understanding of crystallographic defects at the diamond surface [1], how this is related to epitaxial growth processes and the potential impact of such defects on electronic device parameters, such as band bending  [2] and Fermi level pinning. I will detail our efforts to use such understanding to control the surface chemistry of diamond to fabricate quantum electronic and electron emission devices, including for medical diagnostic imaging applications  [3].

I will also describe the increasing toolbox of diamond surface chemistries and interfaces, including silicon [4] related terminations, interfacing with cubic silicon carbide [5]. To support these surface chemistry studies we have established a protocol for quantification of oxygen terminated species on the diamond surface, showing that traditional x-ray photoelectron spectroscopy assignments do not apply [6]. This expanding toolbox of surface terminations suggests that alternatives to hydrogen termination are possible in surface transfer doping [7] and negative electron affinity devices [8] for electron emission. I will particularly talk about our progress towards increased stability in non-Hydrogen terminated surfaces for low work function devices.