High mobility of (111)-oriented large-domain (>100 μ m) poly-InSb on glass by rapid-thermal crystallization of sputter-deposited films

Rapid-thermal annealing (RTA) of InSb precursor films, deposited by sputtering using an Ar plasma at room temperature, has been investigated to achieve high carrier mobility on low-cost glass substrates. Although InSb films containing residual Ar (∼1%) were partially lost by evaporation during RTA, such evaporation during RTA is suppressed by reducing the residual Ar to ∼0.3%. The crystallinity of the films is significantly increased by RTA at temperatures above 400 °C. The electron mobilities of the films increase with increasing RTA temperature up to 490 °C, showing the maximum values (9000-10 000 cm2 V-1 s-1) at 490 °C, and then, the mobilities decrease at RTA temperatures above 490 °C. The mobilities of 9000-10 000 cm2 V-1 s-1 are obtained for films with a wide range of thickness (300-1000 nm) grown at 490 °C. Detailed analysis indicated that the high carrier mobilities are realized by preferentially (111)-oriented large crystal domains (diameter: >100 μm), obtained by the regrowth of randomly oriented small grains, together with a low barrier height (16 meV) at the sub-domain boundaries (twin boundaries) in the large domains. The RTA after the sputtering technique will facilitate high-performance InSb-based devices with low production costs.