High-quality and low-temperature epitaxial Si films deposited at very high deposition rate

Low-temperature epitaxy at temperatures between 550 degreesC and 650 degreesC using ion-assisted deposition enables the formation of Si films with minority-carrier diffusion lengths deposited at rates previously only conceivable using high-temperature chemical vapor deposition at growth temperatures exceeding 1000 degreesC. Using quantum efficiency and photoluminescence measurements, we investigate charge carrier recombination in Si films formed by ion-assisted deposition at temperatures between 460 degreesC and 650 degreesC. Silicon films deposited at a temperature between 460 degreesC and 510 degreesC display relatively short minority-carrier diffusion lengths peaked at a deposition rate around 0.25 mum/min, while we find high diffusion lengths > 20 mum in Si films deposited at a temperature greater than or equal to 550 degreesC with deposition rates between 0.2 and 0.8 mum/min. At a deposition temperature of 650 degreesC we achieve a minority carrier diffusion length of 40 mum in a 21 mum thick epitaxial Si film deposited at a rate of 0.8 mum/min. (C) 2001 Elsevier Science B.V. All rights reserved.