Gallium oxide (Ga 2 O 3 ) has emerged as a highly promising semiconductor material for high-power electronic devices and deep-ultraviolet optoelectronic applications, owing to its wide bandgap of (4.5-4.9 eV), high breakdown electric field (8 MV/cm), and large Baliga’s figure-of-merit (3000). x Despite these promising properties, the heteroepitaxial growth of high-quality Ga₂O₃ films remains challenging. Conventional approaches rely heavily on lattice-matching strategies, such as using buffer layers like GaN or AlN, to mitigate strain. However, these methods are fundamentally limited by residual lattice mismatch, inducing dislocations and defects that degrade device performance. Overcoming these barriers is critical for realizing scalable, high-performance Ga₂O₃-based devices.
The Solution: To address these issues, a team of researchers from Xiamen University have developed a bond-angle-mediated nucleation strategy. This grown involves inserting a precisely engineered gallium oxynitride (GaON) layer on a sapphire substrate with a bond angle (≈90.27°) that closely matches the atomic structure of β-Ga₂O₃, facilitating strain-free epitaxial growth.
This work demonstrated high-quality β -Ga 2 O 3 film grown on sapphire substrates via plasma-assisted molecular beam epitaxy (PAMBE) using a multilayer transition strategy that incorporates an AlN/GaN buffer layer and a GaON nucleation layer. First-principles calculations revealed that GaON's lower effective plane energy enhances nucleation and crystal quality. Experimentally, high-resolution TEM and XRD analyses confirmed the formation of high-crystal-quality β-Ga₂O₃ films with remarkably reduced dislocation densities. The heterostructures led to ultraviolet photodetectors with outstanding performance metrics, dark current as low as 13 pA, responsivity reaching 3821.6 A/W, and a specific detectivity of 3.3 × 10¹⁶ Jones. The devices also demonstrated rapid response times (rise/decay: 30/20 ms), underscoring the technological promise of bond-angle engineering in wide-bandgap heteroepitaxy.
The Future: Future research will further advance this strategy, several research directions merit attention: First, extending this approach to other systems, such as silicon or flexible substrates, could facilitate heterogeneous integration and flexible optoelectronics. Second, optimizing the GaON gradient and interfacial structure may further reduce defects and enhance carrier transport, improving device reliability in photodetection and power electronics. Third, integrating β -Ga 2 O 3 detectors with readout circuits or neuromorphic architectures could enable advanced ultraviolet sensing and in-memory computing. Finally, while the current GaON layer is fabricated via oxygen plasma treatment, developing more scalable and controllable synthesis methods, such as atomic layer deposition or chemical vapor deposition, will be essential for industrial adoption. By advancing these aspects, this work establishes the presented bond-angle-mediated nucleation as a paradigm for growing high-quality wide-bandgap semiconductor heterostructures.
The Impact: This work providing a generalizable strategy for the heteroepitaxial growth of mismatched semiconductor systems.
The research has been recently published in the online edition of Materials Futures , a prominent international journal in the field of interdisciplinary materials science research.
Reference: Shuaihang Xu, Chengchao Li, Yuhan Yang, Chengyi Tian, Xingkun Peng, Hao Long, Minghui Hong, Weifeng Yang. Bond-angle modulation in the nucleation layer overcomes the lattice-mismatch limits in Ga2O3 heteroepitaxy[J]. Materials Futures , 2026, 5(3): 035701. DOI: 10.1088/2752-5724/ae4e4c
Bond-angle modulation in the nucleation layer overcomes the lattice-mismatch limits in Ga2O3 heteroepitaxy
26-Mar-2026