Analysis of deep level defects in nitrogen post-deposition annealed Ga2O3/SiC hetero-structured Schottky diodes grown by mist-CVD

We investigated the electrical characterization and defect properties of Ga2O3/SiC hetero-structured Schottky diodes manufactured by mist chemical vapor deposition. For a comprehensive analysis of the impact of post deposition annealing with nitrogen (N-2), various characterization techniques were employed, including current density-voltage (J-V), capacitance-voltage (1/C-2-V), atomic force microscopy (AFM), and deep level transient spectroscopy (DLTS). The on/off ratios, barrier heights and ideality factors of non-annealed and N-2-annealed diodes were investigated using J-V characteristics. It was confirmed that electrical characteristics were improved in the N-2-annealed diode. By analyses of 1/C-2-V characteristics, the built-in voltage (V-bi) and near surface to bulk carrier concentrations were obtained. Surface topography and roughness, observed through AFM, indicated enhanced crystal quality of the N-2-annealed diode. Deep level trap parameters and possible distributions of each trap were extracted from DLTS spectra and Arrhenius plots. The N-2-annealing process increased the defects originating from extrinsic impurities at 0.226 eV, while decreasing the traps associated with oxygen vacancies at 0.950 eV and 1.257 eV, which can act as recombination centers. This suggests that the N-2-annealing process reduces oxygen vacancies by nitrogen atoms occupying the vacancy sites, leading to a more ordered crystal lattice. Consequently, electrical conductivity, carrier mobility, and overall device performance could be enhanced.