Microdoping compensation of microcrystalline silicon obtained by hot-wire chemical vapour deposition

Undoped hydrogenated microcrystalline silicon was obtained by hot-wire chem ical vapour deposition at different silane-to-hydrogen ratios and low tempe rature (< 300 degrees C). As well as technological aspects of the depositio n process, we report structural, optical and electrical characterisations o f the samples that were used as the active layer for preliminary p-i-n sola r cells. Raman spectroscopy indicates that changing the hydrogen dilution c an vary the crystalline fraction. From electrical measurements an unwanted n-type character is deduced for this undoped material. This effect could be due to a contaminant, probably oxygen, which is also observed in capacitan ce-voltage measurements on Schottky structures. The negative effect of cont aminants on the device was dramatic and a compensated p-i-n structure was a lso deposited to enhance the cell performance. (C) 2000 Elsevier Science B. V. All rights reserved.