2024, Vol. 5, Issue 2, Part A
Role of surface and interface states in reverse leakage of as-grown and regrown GaN-on-GaN Schottky diodes
Author(s): Nimal Perera, Anjali Fernando and Suresh Wijesinghe
Abstract: Gallium Nitride (GaN)-on-GaN Schottky diodes are pivotal in high-power and high-frequency applications due to their superior material properties. However, reverse leakage current remains a significant challenge, primarily influenced by surface and interface states. This study aims to investigate the role of surface roughness, defect density, and passivation layers in modulating reverse leakage currents in as-grown and regrown GaN-on-GaN Schottky diodes. As-grown samples were fabricated using Metal-Organic Chemical Vapor Deposition (MOCVD), while regrown samples underwent an additional epitaxial growth step to improve material quality. Passivation layers, including Silicon Nitride (SiN) and Aluminum Oxide (Al₂O₃), were applied to analyze their effectiveness in mitigating leakage currents. Surface morphology and defect density were characterized using Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM), while surface state analysis employed X-ray Photoelectron Spectroscopy (XPS) and Scanning Capacitance Microscopy (SCM). Electrical properties, including reverse leakage currents, were evaluated through current-voltage (I-V) measurements. Results revealed that regrown samples exhibited significantly lower surface roughness (0.75 nm) and defect density (1.3 × 10⁸ cm⁻²) compared to as-grown samples (1.25 nm and 2.1 × 10⁸ cm⁻², respectively). Reverse leakage currents were reduced in regrown samples (10.93 μA) compared to as-grown samples (16.80 μA). Among the passivation layers, Al₂O₃ demonstrated superior performance in minimizing leakage across both sample types. However, statistical analysis (p-value = 0.3789) indicated that the observed improvements, while promising, lacked strong statistical significance, suggesting the persistence of deep-level traps and interface defects. In conclusion, regrowth techniques and Al₂O₃ passivation substantially improve GaN-on-GaN Schottky diode performance by reducing surface roughness, defect density, and reverse leakage currents. Future research should focus on hybrid passivation strategies, advanced epitaxial growth techniques, and machine-learning-assisted optimization to address residual interface trap challenges and enhance device reliability further.
DOI: 10.22271/27084531.2024.v5.i2a.71
Pages: 19-24 | Views: 69 | Downloads: 27
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How to cite this article:
Nimal Perera, Anjali Fernando, Suresh Wijesinghe. Role of surface and interface states in reverse leakage of as-grown and regrown GaN-on-GaN Schottky diodes. Int J Res Circuits Devices Syst 2024;5(2):19-24. DOI: 10.22271/27084531.2024.v5.i2a.71
