研究目的
To investigate the structural and optical properties of AlN/GaN and AlN/AlGaN/GaN thin films on silicon substrate prepared by plasma-assisted molecular beam epitaxy (MBE).
研究成果
The AlN/GaN and AlN/AlGaN/GaN thin films were successfully grown on silicon substrate using plasma-assisted MBE. Structural analysis via AFM showed surface roughness values of 3.677 nm and 10.333 nm, respectively. XRD confirmed epitaxial growth with hexagonal structure, and PL spectra indicated good optical quality with no yellow luminescence. Raman spectroscopy revealed active modes, supporting the films' quality. These heterostructures show promise for applications in optoelectronics, photovoltaics, and radiofrequency devices due to their excellent properties.
研究不足
The AlN element was not detected in XRD analysis, possibly due to diffusion into silicon or thin layer issues, indicating limitations in detection sensitivity or sample homogeneity. The absence of certain Raman modes may be due to film thickness. The study is limited to specific growth conditions and characterization techniques, and further optimization may be needed for improved crystalline quality.
1：Experimental Design and Method Selection:
The study used plasma-assisted molecular beam epitaxy (MBE) to grow AlN/GaN and AlN/AlGaN/GaN heterostructures on Si (111) substrate, following a method with minor modifications from previous research. High-purity Gallium (7N) and Aluminium (6N5) were used for growth.
2：Sample Selection and Data Sources:
Silicon (111) substrate was chosen for its good conductivity, low cost, and compatibility with silicon device technologies.
3：List of Experimental Equipment and Materials:
Equipment includes MBE system, atomic force microscope (AFM), X-ray diffractometer (XRD, Shimadzu XRD-6000), photoluminescence spectroscopy (PL) setup with Xenon source lamp, and confocal Raman microscope. Materials include high-purity Gallium and Aluminium sources.
4：Experimental Procedures and Operational Workflow:
Thin films were fabricated via MBE. Structural properties were analyzed using AFM for surface imaging and roughness, XRD for crystal structure, and optical properties using PL and Raman spectroscopy. Measurements were conducted at room temperature with specific excitation wavelengths (e.g., 250 nm for PL).
5：Data Analysis Methods:
XRD data were analyzed using the Scherrer equation to calculate crystallite size. PL and Raman spectra were interpreted to assess optical quality and vibrational modes.
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