Enhancing the Reverse Threshold Limit for Heteroepitaxial Diamond-Based Pseudovertical Schottky Diodes: Dependency on the Metal Contact Size

Abstract

Diamond is a superior material with unique properties among wide band gap semiconductors; it is the most promising candidate for power devices due to its high breakdown voltage and low power losses. The heteroepitaxially grown diamond has been introduced to overcome the size limitation of homoepitaxial plates. Nevertheless, several properties still need to be reported, such as the size upscaling compatibility of Schottky diodes to power electronics devices. Therefore, the performance of pseudovertical Schottky diodes fabricated on heteroepitaxial diamonds has been investigated as a function of device size. Electrical characteristics for more than 100 Schottky barrier diodes (SBDs) have been studied; they can be categorized as 1 mm X-SBDs, 200 μm X-SBDs, 90 μm X-SBDs, and 65 μm X-SBDs, where X is Mo, Cr, and Pt. The Schottky barrier height showed a dependency on the device size; for the Mo-SBDs, the barrier height increased from 1.29 to 1.58 eV for 65 μm and 1 mm diameters at room temperature, respectively. Similar behavior was also observed for Cr and Pt devices. In addition, there is a severe reduction in the specific-on resistance for small-diameter SBDs. The high-temperature dependence of the device parameters and performance was also studied. All SBDs showed a decrease in the ideality factor and specific-on resistance with the temperature, in addition to the increase in the barrier height. The breakdown voltage was enhanced by 6-fold for the 65 μm compared with 1 mm Mo-SBDs. 90 and 65 μm devices showed a promising potential for power applications according to Baliga’s power figure of merit that exceeded 5 MW/cm2 for 65 μm Pt-SBDs as well as the breakdown voltage of 453 V which represents the best-reported value for the heteroepitaxial-diamond-based device.