研究目的
To compare the temperature-dependent direct and indirect bandgap emissions of Ge1-x-ySixSny and Ge1-ySny alloys grown on Ge-buffered Si substrates, focusing on how Si incorporation affects optical properties, strain, and bandgap characteristics.
研究成果
Si incorporation into GeSn increases bandgap widths and blue-shifts emission peaks, making ternaries indirect bandgap materials even at high Sn concentrations, unlike binaries which become direct at lower Sn. Strain effects dominate over small Si composition changes, and compressive strain can cause valence band splitting. These findings aid in developing GeSiSn-based photonic devices but highlight the need for higher Sn concentrations in ternaries to achieve direct bandgap behavior.
研究不足
The study is limited to specific Sn and Si concentrations; variations in strain and defects may affect results. Thinner ternary layers and increased defects could lead to weaker PL intensities. The crossover to direct bandgap in ternaries requires higher Sn concentrations than in binaries, which may not be fully optimized for device applications.
1：Experimental Design and Method Selection:
The study involved temperature-dependent photoluminescence (PL) measurements from 5 to 300 K using a cryostat, with excitation by an 830-nm laser from a tunable Ti-Sapphire laser pumped by an Ar-ion laser. Gaussian curve fitting was employed to analyze PL spectra.
2：Sample Selection and Data Sources:
Samples included ternary GeSiSn and binary GeSn alloys with specific Sn and Si concentrations, grown on Ge-buffered Si substrates using gas source molecular epitaxy (GS-MBE) or ultrahigh vacuum chemical vapor deposition (UHV-CVD).
3：List of Experimental Equipment and Materials:
Equipment included a cryostat, tunable Ti-Sapphire laser, Ar-ion laser, ?-m spectrometer with a 1.6 μm blazed grating, liquid nitrogen cooled extended InGaAs detector, long-pass filters, and commercial software MagicPlot for curve fitting. Materials were the grown semiconductor films.
4：6 μm blazed grating, liquid nitrogen cooled extended InGaAs detector, long-pass filters, and commercial software MagicPlot for curve fitting. Materials were the grown semiconductor films.
Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: PL measurements were conducted at various temperatures and laser powers. Spectra were collected, dispersed by the spectrometer, and analyzed using Gaussian fits to determine peak positions and separations.
5：Data Analysis Methods:
Data were fitted with Gaussian equations and Varshni's type equations to model temperature dependence of bandgap energies. Strain and compositions were determined by high-resolution X-ray diffraction (HRXRD) and Rutherford backscattering spectroscopy (RBS).
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
