Doping investigation of structured GaN devices by highly lateral resolved TOF-SIMS

• Doped GaN layers with processed trench structures were measured by highly lateral resolved TOF-SIMS with a lateral resolution of 100 nm. • A topography and distortion correction for realistic visualization of 3D TOF-SIMS data was implemented. • Ga and Mg concentrations and doping levels around the gate trench were successfully visualized. • An impact of the gate trench processing or the dielectric deposition on the Mg doping level close to the gate trench could be excluded. The measurement of doping concentrations is a fundamental need for the development and processing of power electronic devices like normally-off semi-vertical GaN trench MOSFETs. We employed highly laterally resolved TOF-SIMS to evaluate the doping levels of the n- and p - doped layers close to the gate trench. A lateral resolution of approx. 100 nm was achieved sufficient to resolve the gate trench geometry. Furthermore, the analysis and the visualization of the 3D data was optimized by implementing the correction of the topography and image distortions. No change of the Mg and Si doping of the n- and p - layers close to gate trench sidewall was observed.