Si/AlN p-n heterojunction interfaced with ultrathin SiO2

• Published in: Applied surface science 2025-02, Vol.682, p.161737, Article 161737
• Main Authors: Abbasi, Haris Naeem, Lu, Yi, Zhou, Jie, Wang, Ding, Sun, Kai, Wang, Ping, Gong, Jiarui, Liu, Dong, Liu, Yang, Singh, Ranveer, Mi, Zetian, Ma, Zhenqiang
• Format: Article
• Language: English
• Subjects: Band alignment; P-type doping; Semiconductor grafting; Si/AlN heterojunction; UWBG materials
• ISSN: 0169-4332
• DOI: 10.1016/j.apsusc.2024.161737

[Display omitted] •Developed a Si/AlN heterojunction via semiconductor grafting, advancing materials integration for optoelectronics.•XPS confirmed Type-I heterojunction with 2.84 eV valence and 2.11 eV conduction band offsets.•Fabricated diode achieved 1.92 ideality factor, 3.3 × 10⁴ rectification ratio, and 3.9 V turn-on voltage. Ultra-wide bandgap (UWBG) materials offer significant potential for high-power RF electronics and deep ultraviolet photonics. Among these, AlxGa1−xN stands out due to its tunable bandgap (3.4 eV to 6.2 eV) and excellent material properties. However, achieving efficient p-type doping in high aluminum composition AlGaN remains a challenge. This study presents a novel approach by fabricating a p+Si/n-AlN/n+AlGaN heterojunction using semiconductor grafting. Atomic force microscopy (AFM) revealed smooth surfaces for AlN and the nanomembrane, with roughness values of 1.96 nm and 0.545 nm, respectively. High-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) confirmed a sharp and well-defined Si/AlN interface with minimal defects and strong chemical bonding. X-ray photoelectron spectroscopy (XPS) measurements identified a type-I heterojunction with a valence band offset (ΔEv) of 2.73–2.84 eV and a conduction band offset (ΔEc) of 2.22–2.11 eV. The pn diode devices exhibited linear current–voltage (I-V) characteristics, an ideality factor of 1.92, and a high rectification ratio of 3.3 × 104, with a turn-on voltage of 3.9 V. Temperature-dependent I-V measurements showed stable operation up to 90 °C. The heterojunction’s high-quality interface and impressive electrical performance underscore its potential for advanced AlGaN-based optoelectronic and electronic applications.