Influence of sputtering conditions on H content and SiH bonding in aSi: H alloys

The influence of sputtering conditions on H concentration and SiH bonding has been determined for the case of diode reactive sputtering of Si in ArH mixtures, and a simple model for SiH reaction kinetics has been developed. H content and SiH bonding can be varied and controlled over wide ranges by appropriate selection of sputtering conditions. SiH reaction kinetics are found to be governed primarily by deposition rate (reaction time), H partial pressure (H availability) and possibiy substrate temperature (mobility of Si and H on the surface of the growing film). H concentration increases with decreasing deposition rate and increasing H partial pressure. SiH bonding increases with increasing deposition rate and decreasing H partial pressure. Polymerization of H and Si (SiH₂, SiH₃) occurs for lowest deposition rates and highest H partial pressures. Polymerization reactions are enhanced in films deposited at very high target power densities. The high power density causes substrate temperature to be higher than expected, and the enhanced polymerization may be due to increased Si and H surface mobility at the elevated temperatures.     

Bonding and composition diagrams for sputtered a-Si : H

The combined influence of H partial pressure (p_H) and deposition rate (R_D) on Si-H bonding and total H content in diode-sputtered a-Si : H is presented in two simple graphs for the case of substrate temperature (T_s) equal to 225°C. Similar to a phase diagram, the graphs predict the H content and Si-H bonding that will result if a deposition is carried out with any prescribed pair of values (p_H, R_D), where 0.04 < p_H < 10 Paand 0.01 < R_D < 1 nm/sec. Well defined regions of Si-H bonding represented by dominant infrared stretching absorptions at 2000, 2090 and 2150 cm^?1 are obvious in the bonding diagram. The absorption at 2090 cm^?1 is the most commonly observed and is obtainable over a wide range of intermediate values of p_H and R_D. The absorption at 2000 cm^?1 is dominant only for the lowest p_H and the highest R_D. The absorption at 2150 cm^?1 is dominant in films deposited at high p_H and low R_D. The composition diagram shows that highest total H content is obtained for low R_D and high p_H, and lowest total H content results for high R_D and low p_H     

教师教学水平的时齐马尔可夫链评估方法

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