研究目的
To investigate the effects of growth conditions, such as the II/VI ratio and growth rate, on twin formation in CdTe films grown on (211) Si substrates using vapor-phase epitaxy with a metallic Cd source, and to understand the growth mechanism.
研究成果
The orientation of CdTe films on (211) Si substrates can be controlled by the II/VI ratio, with (133) orientation favored at lower II/VI and (211) at higher II/VI. The crystalline quality of (133) CdTe is superior to (211) CdTe, as indicated by lower FWHM values. The growth mechanism involves step-flow growth for (133) CdTe and spontaneous nucleation for (211) CdTe, depending on the II/VI ratio. This provides insights for optimizing CdTe growth for applications like radiation detectors.
研究不足
The study is limited to specific growth conditions (e.g., temperature of 600°C, atmospheric pressure) and substrate type ((211) Si without buffer layers). The use of metallic Cd source may have implications for cost and scalability, but comparative studies with other precursors are not extensively covered. The explanation of growth mechanisms is based on assumptions and may require further validation.
1：Experimental Design and Method Selection:
A horizontal flow reactor made of quartz at atmospheric pressure was used for vapor-phase epitaxy. Metallic Cd (6N purity) and diisopropyl-telluride (DiPTe) served as group-II and -VI precursors, respectively, with H2 as the carrier gas. The II/VI ratio was controlled by varying the input supply rates of Cd and DiPTe.
2：Sample Selection and Data Sources:
(211) Si substrates were used after a typical chemical cleaning process and annealing at 1000°C for 30 min in H2 ambient to remove silicon oxide. No buffer layers or special surface treatments were applied.
3：List of Experimental Equipment and Materials:
Equipment included a quartz horizontal flow reactor, heaters for temperature control, scanning electron microscope (SEM), x-ray diffraction (XRD) equipment, and atomic force microscope (AFM). Materials included metallic Cd (6N purity), DiPTe, H2 gas, and (211) Si substrates.
4：Experimental Procedures and Operational Workflow:
Substrates were annealed and then CdTe films were grown at 600°C for 60 min. The II/VI ratio and growth rate were varied by adjusting precursor supply rates. Films were characterized using SEM for morphology, XRD for orientation and crystalline quality, and AFM for surface steps.
5：Data Analysis Methods:
XRD was used to determine film orientation and full width at half maximum (FWHM) for crystalline quality assessment. SEM and AFM images were analyzed to observe surface features and step structures.
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