Microcrystalline silicon deposited by the hot-wire CVD technique

Hot-wire chemical vapour deposition (HW-CVD) is a well-known technique to d eposit amorphous silicon with high deposition rates from the decomposition of silane and hydrogen gases. By changing the hydrogen and silane how rates , it is possible to observe a transition from amorphous silicon (a-Si:H) to microcrystalline silicon (mu c-Si:H). In this study, structural and electr ical properties of layers deposited as a function of silane concentration i n the gas are presented. Ellipsometry and X-ray diffractometry have been us ed to assess the structure of the films. Steady-state photoconductivity, st eady-stale photocarrier grating, and modulated photocurrent experiments hav e been carried out to characterise both majority and minority carrier trans port properties. Finally. the addition of phosphine and diborane in the rea ctor allows the deposition of n- and p-type layers with conductivities up t o 10 and 1 s cm(-1), respectively. making possible the realisation of HW-CV D solar cells. (C) 2000 Elsevier Science S.A. All rights reserved.