研究目的
To demonstrate the feasibility of using mild annealing process to create SiGe nanocrystals within Si-sub/SiO2-buffer/(TiO2/SiGe/TiO2)3/Al system without the formation of a SiO2 insulating layer, thus increasing the spectral intensity of TiO2 for visible to near infrared regime.
研究成果
The study successfully demonstrated the formation of SiGe nanocrystals in a TiO2 matrix using mild annealing without SiO2 formation, leading to enhanced photoconductive properties with a red shift in photocurrent peak with decreasing temperature, attributed to SiGe nanocrystals and defects in the structure.
研究不足
The study is limited to specific annealing conditions (600°C for 5 min) and material system; potential limitations include the scalability of the process for industrial applications and the need for further optimization of annealing parameters to enhance photoconductivity.
1：Experimental Design and Method Selection:
The study involved preparing a tri-stacked multilayer structure (SiO2-buffer/TiO2-cap/(GeSi/TiO2)3) on Si (100) wafers using reactive direct current magnetron sputtering (dcMS) for TiO2 layers and co-sputtering Si and Ge by dcMS for the GeSi layer. Furnace annealing was performed at 600°C in N2 ambient for 5 minutes to form nanocrystals. Morphology was analyzed using grazing incidence XRD (GIXRD) and transmission electron microscopy (TEM). Photoconductive properties were measured by photocurrent spectra at different voltages and temperatures.
2：Sample Selection and Data Sources:
Samples were deposited on Si (100) wafers. Data sources include GIXRD scans, HRTEM images, and photocurrent measurements.
3：List of Experimental Equipment and Materials:
Equipment includes a direct-current magnetron sputtering system (with Advanced Energy MDX500 power supply), furnace for annealing, GIXRD (Philips X'pert diffractometer), TEM (Jeol ARM 200F microscope), and setups for photocurrent measurements. Materials include Si wafers, TiO2, Si, Ge targets, Ar and O2 gases, and aluminium for contacts.
4：Experimental Procedures and Operational Workflow:
The workflow involved depositing layers via sputtering with controlled gas flow rates and pressures, annealing the samples, evaporating aluminium contacts, and performing GIXRD, TEM, and photocurrent measurements under various conditions.
5：Data Analysis Methods:
Data analysis involved interpreting GIXRD peaks, HRTEM images for nanocrystal size and morphology, and analyzing photocurrent spectra for peak shifts and intensities with voltage and temperature changes.
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