研究目的
To compare simulated and measured optical properties of a short-period GaAs/AlxGa1?xAs distributed Bragg re?ector (DBR) and to understand the factors that affect DBR behaviour, aiding in the calibration of growth techniques for more complicated devices.
研究成果
Accurate layer thicknesses are critical to simulating the features of the sample correctly. Substrate corrections (internal reflections and absorption) affect the transmission amplitude but not the overall shape of the spectrum. The Al content of the AlxGa1?xAs was slightly lower than expected, but the effect on the transmission was minimal, implying a reasonable tolerance to composition.
研究不足
The study is limited by the accuracy of the layer thickness measurements and the assumption that the substrate is completely transparent in the region of interest. The effect of doping on the refractive indices of the materials was not fully accounted for in the simulations.
1：Experimental Design and Method Selection:
The study involves growing a 6-period GaAs-Al0.9Ga0.1As DBR via molecular beam epitaxy (MBE) and measuring its optical properties using a spectrophotometer. Optical modelling was carried out using TFCalc and transfer matrix simulations.
2：9Ga1As DBR via molecular beam epitaxy (MBE) and measuring its optical properties using a spectrophotometer. Optical modelling was carried out using TFCalc and transfer matrix simulations.
Sample Selection and Data Sources:
2. Sample Selection and Data Sources: The sample is a 6-period GaAs-Al0.9Ga0.1As DBR grown on an n-GaAs substrate. Optical measurements were performed using a Cary 5000 spectrophotometer.
3：9Ga1As DBR grown on an n-GaAs substrate. Optical measurements were performed using a Cary 5000 spectrophotometer.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Veeco GenXplor II MBE system, Cary 5000 spectrophotometer, Leica EM-TIC020 ion beam cutter, Bruker MultiMode 8 AFM, CAMECA IMS 4f secondary-ion mass spectrometer.
4：Experimental Procedures and Operational Workflow:
The DBR was grown, its optical properties measured, and simulations were incrementally improved to match the measurements. Layer thicknesses were measured using BEXP and AFM, and composition was analyzed using SIMS.
5：Data Analysis Methods:
The simulation was adjusted to account for internal consistency error, incorrect layer thicknesses, and absorption due to substrate doping. The extinction coefficient of the substrate was calculated from reflectance and transmittance data.
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