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Role of chamber pressure on crystallinity and composition of silicon films using silane and methane as precursors in hot-wire chemical vapour deposition technique
摘要： Hot-wire chemical vapour deposition is a versatile technique to deposit a-Si:H and nc-Si films at higher deposition rate (~5-10 ?/sec) as compared to Plasma enhanced chemical vapour deposition (1-2 ?/sec). We report the deposition of highly crystalline Si films at very high deposition rate (≥ 40?/sec) by adding methane to silane during thermal/catalytic decomposition. A series of films were deposited by varying the chamber pressure between 10-100 Pa at a substrate temperature of 300 °C and filament temperature 2000 °C. The hydrogen diluted silane (10% silane in hydrogen) and pure methane were used as precursors and gas flow rate ratio was kept constant at 10. Films prepared at lower pressure (≤ 20 Pa) were more crystalline and do not contain any trace of carbon atoms. Bandgap was found to increase from 1.24-1.63 eV when pressure was increased. It was observed that chamber pressure plays a key role in determining the crystallinity, disorder and composition of these films. Addition of methane to hydrogen diluted silane increased deposition rate and crystallinity of Si films at low pressure (≤ 20 Pa). Above 20 Pa pressure, carbon atoms signature was obtained. SiC films were obtained when pressure was > 100 Pa.
关键词： Deposition rate,Si films,Crystallinity,Hot-wire chemical vapour deposition
更新于2025-11-21 11:01:37
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p+ polycrystalline silicon growth via hot wire chemical vapour deposition for silicon solar cells
摘要： Hot wire chemical vapour deposition (HWCVD) is explored as a way of growing boron-doped silicon for photovoltaic devices. Deposition temperatures are measured using a custom-built monitoring system for two different filament configurations within the HWCVD tool. A refined fabrication process is presented, using an altered filament arrangement, that currently provides a maximum deposition temperature of 535 oC, for growing boron-doped silicon films via HWCVD, with the inclusion of a short post-deposition anneal at 800 oC for 2 minutes. Transmission electron microscopy reveals improvements in interfacial quality, as well as larger grains present after post-annealing treatments. In addition, re-crystallisation of as-deposited amorphous Si films under a short anneal is confirmed using Raman spectroscopy. The enhancements in morphology translate to a boost in current rectification based on our dark current-voltage measurements. This is further supported by secondary-ion mass spectrometry analysis, presenting p+ properties with uniform doping in the 1021 cm-3 region.
关键词： Selective area electron diffraction,Crystallisation,Emitter,Hot wire chemical vapour deposition,Silicon solar cells,Transmission electron microscopy
更新于2025-09-23 15:19:57