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

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 × 10(16) cm(−3) to 6 × 10(18) 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.