In the quest for more efficient and durable materials for the energy sector, researchers have long been fascinated by the potential of β-Ga2O3. This wide-bandgap semiconductor has garnered significant attention due to its robustness and suitability for high-power and high-frequency applications. However, a persistent challenge has been the achievement of stable p-type conductivity, a crucial factor for creating functional electronic devices. A groundbreaking study led by Yimin Liao from the Advanced Materials Thrust, Function Hub, Hong Kong University of Science and Technology (Guangzhou), has made significant strides in this area, offering a promising pathway to overcome this hurdle.
The research, published in Materials Today Advances, focuses on the innovative use of ion implantation to co-dope β-Ga2O3 with selenium (Se) and magnesium (Mg). This method introduces defect energy levels near the conduction band and acceptor doping elements, which are essential for achieving p-type conductivity. The study employed a 50 kV acceleration voltage to reach a peak purity concentration depth, resulting in high concentrations of Se and Mg, reaching 2.35 × 1022/cm3 and 8.99 × 1021/cm3 respectively. These concentrations were consistent with simulation results, validating the effectiveness of the ion implantation process.
The researchers then subjected the co-doped β-Ga2O3 to rapid thermal annealing at 850°C in an oxygen environment. This step was crucial for mitigating the damage caused by implantation and ensuring the material’s structural integrity. “The annealing process was pivotal in stabilizing the doped material,” Liao explained. “It helped in reducing defects and enhancing the overall quality of the β-Ga2O3, making it more suitable for practical applications.”
One of the most intriguing findings of the study was the ability to slightly tune the bandgap of β-Ga2O3 from 4.42 to 4.37 eV by adjusting the Se and Mg implantation doses. This tunability is a significant advancement, as it allows for greater flexibility in designing electronic devices tailored to specific energy applications. The experimental characteristics revealed valence band maximum values and exhibited potential p-type behavior achieved by Se-Mg co-doping. Hall measurements further indicated probable p-type conductivity, although further verification is required.
The study also delved into the theoretical underpinnings of the doping process. First-principles density functional theory simulations provided calculations of substitutional defect formation energies and Fermi levels within the β-Ga2O3 lattice. These simulations elucidated the causes of electronic structure changes induced by doping, offering a deeper understanding of the material’s behavior at the atomic level.
The implications of this research are far-reaching for the energy sector. Achieving stable p-type conductivity in β-Ga2O3 could revolutionize the development of high-power electronic devices, such as power converters and inverters, which are essential for renewable energy systems. The ability to fine-tune the bandgap and achieve p-type conductivity opens up new possibilities for creating more efficient and durable energy solutions.
As the energy sector continues to evolve, the need for advanced materials that can withstand harsh conditions and operate efficiently is paramount. The work by Yimin Liao and his team represents a significant step forward in this direction, paving the way for future innovations in the field. With further verification and refinement, the Se-Mg co-doping method could become a cornerstone in the development of next-generation energy technologies.
