Characterization of Schottky Barrier Diodes on Heteroepitaxial Diamond on 3C-SiC/Si Substrates

摘要

We demonstrated and characterized Schottky barrier diodes (SBDs) fabricated on heteroepitaxial diamond films grown onto 3C-SiC/Si substrates. SBDs showed clear diode properties with rectification ratios above 10(9) at 5 V and maintained above 10(8) even at 500 K. Temperature dependence of the Schottky barrier height (SBH) and the ideality factor was explained by assuming inhomogeneous Schottky barriers following the Gaussian distribution. For leakage current analysis, two types of defects, linear pits (LPs) and nonepitaxial crystals (NCs), were shown to be fatal defects, causing the flow of leakage currents. The leakage current was found to be an exponential function of the length of the LPs and a linear function of the size of the NCs. These defects can be suppressed by highly oriented heteroepitaxial diamond films with reduction of tilt and twist spread for diamond nuclei and optimized growth condition. Moreover, intrinsic layer thickening and inserting a buffer layer stopping propagation of dislocations are also effective. By reducing both crystal defects, we can obtain device properties comparable to SBDs fabricated on homoepitaxial diamond films because the leakage currents can be suppressed.