FIB in-situ fabrication of pseudo vertical diamond Schottky diode: H-terminated ohmic contact and O-terminated Schottky barrier

Abstract

Among diamond-based devices, the Schottky barrier diode (SBD) shows significant promise, achieving high breakdown voltages (9.5 MV⋅cm ) and reduced serial resistance (1 Ω) through structural advancements. The performance of SBDs depends on the interface between the Schottky contact, surface termination, and diamond. Studies have highlighted the impact of interface configuration on Schottky barrier height (SBH), particularly for hydrogen (H) and oxygen (O)-terminated diamonds. H-terminated surfaces exhibit negative electron affinity (NEA), whereas O-terminated surfaces show positive electron affinity (PEA). This surface behaviour has a strong impact on electron affinity, surface conductivity, work function, and the SBH which are critical for device performance. To know more about the metal-surface-diamond interface, tungsten (W) and platinum (Pt) deposited by electron beam-induced deposition (EBID), in a FIB dual beam, were employed as Schottky contacts on H and O-terminated diamond. The resulting structure has a pseudo vertical configuration with a back ohmic contact on a p ++ boron-doped layer. The current–voltage (I-V) and X-ray photoelectron spectroscopy (XPS) measurements resulted in a SBH of 1.69 eV for W and 1.76 eV for Pt, with an ideal factor (n) of 1.22 and 1.18, respectively. These n values demonstrated a chemical reactivity between metal-surface-diamond. Finally, a combination of two techniques for the SBH estimation is discussed.