研究目的
Investigating the influence of 4H-SiC substrate miscut on the epitaxy and microstructure of AlGaN/GaN heterostructures.
研究成果
The study concludes that the miscut angle of 4H-SiC substrates significantly influences the epitaxy and microstructure of AlGaN/GaN heterostructures. The on-axis sample showed a higher density of threading dislocations and V-shaped defects, while the off-axis sample exhibited a smoother surface and fewer defects. The AlN spacer layer was found to have a uniform thickness and clear interfaces in both cases. The findings suggest that 2° off 4H-SiC substrates are suitable for GaN-based device epitaxy.
研究不足
The study is limited to the structural characterization of AlGaN/GaN heterostructures grown on 4H-SiC substrates with specific miscut angles. The electrical properties and device performance implications of the observed structural features are not explored in this paper.
1：Experimental Design and Method Selection:
The study involved the growth of AlGaN/GaN heterostructures on 'on-axis' and 2° off (0001) 4H-SiC substrates using metalorganic vapor phase epitaxy (MOVPE). Structural characterization was performed using transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and scanning transmission electron microscopy (STEM) combined with energy dispersive X-ray analysis (EDS).
2：Sample Selection and Data Sources:
Two samples were grown on 4H-SiC substrates: Sample-A on almost 'on axis' 4H-SiC (±0.5°) and Sample-B on 2° off axis from the (0001) plane.
3：5°) and Sample-B on 2° off axis from the (0001) plane.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: An EMCORE Turbodisc? D75 metalorganic chemical vapor deposition (MOCVD) system was used for epitaxial growth. Trimethylgallium (TMGa), trimethylaluminum (TMAl), and ammonia (NH3) were used as Ga, Al, and N precursors, respectively. A JEOL 2011 electron microscope operated at 200 kV and an aberration-corrected 'cubed' FEI Titan 60–300 electron microscope operated at 300 kV were used for structural characterization.
4：Experimental Procedures and Operational Workflow:
The substrates were cleaned using solvents and subjected to an in-situ thermal cleaning in flowing H2 at 1100 °C for 10 min before growth initiation. An AlN nucleation layer was deposited, followed by the growth of AlGaN/GaN heterostructures. TEM specimens were prepared using traditional methods, including mechanical polishing and argon ion-milling.
5：Data Analysis Methods:
Electron diffraction analysis, HAADF-STEM imaging, and STEM-EDS elemental mapping were used to analyze the structural properties and elemental composition of the samples.
独家科研数据包，助您复现前沿成果，加速创新突破
获取完整内容
