研究目的
Investigating the growth and properties of silicon thin films under variation of applied power using RF-PECVD technique, focusing on the formation of sub-nanocrystalline phases and their optoelectronic properties.
研究成果
The investigation reveals the existence and segregation of sub-nanocrystalline phase within the amorphous structure, exhibiting high bandgap of ~1.9 eV along with substantial photo and dark conductivities. The formation of such partially crystalline phase explored nearer to the transition regime suggests the suitability of sub-nanocrystalline silicon thin films to replace hydrogenated amorphous silicon in various applications.
研究不足
The study is limited to power variation up to 50 W to avoid powder formation at higher applied power. The exact values of bandgaps measured from UV-Vis spectroscopy and PL characterization tools show slight discrepancy.
1：Experimental Design and Method Selection:
Silicon thin films were deposited on glass and silicon substrates at various applied power from 10 W to 50 W using RF-PECVD technique (
2：56 MHz) under standard growth conditions. Sample Selection and Data Sources:
The deposition pressure was kept as
3：23 Torr while maintaining the substrate temperature at 270 °C. SiH4 (5%, diluted in H2) used as the precursor gas keeping the flow rate as 47 sccm. List of Experimental Equipment and Materials:
Stylus profilometer (Nanomap500Es), UV-visible spectroscopy, Photoluminescence (PL), Temperature dependent conductivity measurements, Keithley 6487 programmable electrometer.
4：Experimental Procedures and Operational Workflow:
The thickness of the films was extracted using stylus profilometer. Optical absorption and the material band gap analysis were performed using UV-visible spectroscopy. Dark conductivity and photo-conductivity measurements were obtained for the samples in a coplanar configuration.
5：Data Analysis Methods:
Activation energies (ΔEa) of the deposited films were obtained from temperature-dependent dark conductivity measurements using the Arrhenius equation.
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