Characterization of vertical Mo/diamond Schottky barrier diode from non-ideal I–V and C–V measurements based on MIS model

• Non- ideal characteristics of a vertical Mo/diamond Schottky barrier diode with Al2O3 field oxide were investigated.
• Schottky barrier height extraction from I-V and C-V measurements suggest Fermi level pinning at metal- diamond interface.
• The diode was analyzed based on Metal- Interfacial layer- Semiconductor (MIS) model.
• The extracted interfacial layer thickness is approximately 0.248 nm.
• The extracted interface states energy distribution is uniformly distributed with values around 1013 eV-1.cm-2.

In this study, we investigated non-ideal characteristics of a diamond Schottky barrier diode with Molybdenum (Mo) Schottky metal fabricated by Microwave Plasma Chemical Vapour Deposition (MPCVD) technique. Extraction from forward bias I–V and reverse bias C− 2–V measurements yields ideality factor of 1.3, Schottky barrier height of 1.872 eV, and on-resistance of 32.63 mΩ·cm2. The deviation of extracted Schottky barrier height from an ideal value of 2.24 eV (considering Mo workfunction of 4.53 eV) indicates Fermi level pinning at the interface. We attributed such non-ideal behavior to the existence of thin interfacial layer and interface states between metal and diamond which forms Metal-Interfacial layer-Semiconductor (MIS) structure. Oxygen surface treatment during fabrication process might have induced them. From forward bias C–V characteristics, the minimum thickness of the interfacial layer is approximately 0.248 nm. Energy distribution profile of the interface state density is then evaluated from the forward bias I–V characteristics based on the MIS model. The interface state density is found to be uniformly distributed with values around 1013 eV− 1·cm− 2.