Enlargement of effective area in Schottky barrier diodes on heteroepitaxial (001) diamond substrates by defect reduction and their radiation tolerance

A major obstacle to realizing diamond electronics is the presence of device-killing defects. Characteristics of diamond-based diodes are degraded with increasing contact size, and a large Ohmic-like leakage current can be generated. Here, we introduced a buffer layer to suppress the killer defects, which extended from the substrate to the epitaxial layer. With the utilization of the buffer layer created using the metal-assisted termination (MAT) technique, Schottky barrier diodes (SBDs) with diametric sizes of Schottky contact ranging from 65 to 1000 mu m were fabricated on heteroepitaxial-grown diamond (001) substrates. The SBDs exhibited an explicit rectifying behavior with a rectification ratio of >10(10) even with 1000 mu m circular contact (7.85 x 10(-3) cm(2)). Satisfying diode parameters were obtained with an ideality factor of 1.52, a Schottky barrier height of 1.66 eV, and a picoampere of leakage current at a reverse bias of 10 V. Interestingly, the diode parameters of the diamond-based SBDs such as ideality factor, Schottky barrier height and rectifying ratio were likely not changed or degraded even after absorption to 1 MGy in the dose of white X-ray. Overall, this demonstration indicates a promising way to realize a large active area of diamond electronics that is applicable to high-output power transmission devices and detector applications.