Numerical simulation analysis of carbon defects in the buffer on vertical leakage and breakdown of GaN on silicon...

Carbon doping in GaN-on-Silicon (Si) epitaxial layers is an essential way to reduce leakage current and improve breakdown voltage. However, complicated occupy forms caused by carbon lead to hard analysis leakage/breakdown mechanisms of GaN-on-Si epitaxial layers. In this paper, we demonstrate the space charge distribution and intensity in GaN-on-Si epitaxial layers from 0 to 448 V by simulation. Depending on further monitoring of the trapped charge density of C_N and C_Ga in carbon-doped GaN at 0.1 μm, 0.2 μm, 1.8 μm and 1.9 μm from unintentionally doped GaN/carbon-doped GaN interface, we discuss the relationship between space charge and plateau, breakdown at C_N concentrations from 6 × 10¹⁶ cm^-3 to 6 × 10¹⁸ cm^-3. The results show that C_N in different positions of carbon-doped GaN exhibits significantly different capture and release behaviors. By utilizing the capture and release behavior differences of C_N at different positions in carbon-doped GaN, the blocking effect of space charge at unintentionally doped GaN/carbon-doped GaN interface on electron conduction was demonstrated. The study would help to understand the behavior of C_N and C_Ga in GaN-on-Si epitaxial layers and more accurate control of C_N and C_Ga concentration at different positions in carbon-doped GaN to improve GaN-on-Si device performance.