研究目的
Investigating the modifications to the optical transmittance of GaN thin film on sapphire substrate under weak magnetic fields.
研究成果
The WMF treatment induces changes in the optical transmittance spectra of GaN thin films, which cannot be fully explained by variations in the optical thickness alone. The study suggests that modifications in the refractive index of GaN or reflection coefficients at the interfaces are necessary to account for the observed discrepancies. The findings indicate that WMF treatment can be used to modify the optical properties of GaN films, potentially through the diffusion of point defects and dissolution of metastable complexes.
研究不足
The study is limited by the assumption that the refractive index of GaN has not changed, focusing instead on modifications in the optical thickness. The discrepancies between experimental and simulated spectra for wavelengths above 700-800 nm suggest that changes in the refractive index or reflection coefficients at the interfaces may also play a role, which were not fully accounted for in the model.
1：Experimental Design and Method Selection:
The study involved measuring the optical transmittance spectra of GaN thin films on sapphire substrates before and after weak magnetic field (WMF) treatment. A three-layer model was used to simulate the transmittance spectra.
2：Sample Selection and Data Sources:
GaN thin films were prepared on Al2O3 sapphire substrates using the metal-organic chemical vapor deposition (MOCVD) technique. The thicknesses of the GaN and Al2O3 layers were 2.0-2.5 μm and 230 μm, respectively.
3：0-5 μm and 230 μm, respectively.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: A diffractive spectrophotometer Specord 210 was used for optical transmittance measurements in the wavelength range from 350 to 1100 nm. A halogen lamp served as the light source.
4：Experimental Procedures and Operational Workflow:
Optical transmittance spectra were measured at room temperature (300 K). The WMF treatment parameters were B = 60 mT, f = 10 Hz, τ = 1.2 ms, with a processing duration of 10 min for 15 days.
5：2 ms, with a processing duration of 10 min for 15 days.
Data Analysis Methods:
5. Data Analysis Methods: The refractive index of GaN was obtained using the Sellmeier dispersion relation. The experimental data were fitted using a three-layer model to analyze the effects of WMF treatments on the optical properties of the GaN film.
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