Because the nc-Si:H deposition is a multi-variable system,
other parameters may also be used to control the crystallinity, such
as the VHF excitation power. In depleting deposition regimes,
increasing the VHF power can effectively increase atomic
hydrogen density, hence increases the crystallinity. One can reduce
the VHF power during the deposition to control the crystallinity.
Other deposition parameters such as substrate temperature,
pressure, and total gas flow rate may also be used, but no
systematic studies have been made.
Table I. J-V characteristics of two pairs of nc-Si:H single-junction solar
cells made using constant (CHD) and profiled (PHD) hydrogen dilution
during the i-layer depositions. The pair of A-C and A-P has poorer
performance than the pair of B-C and B-P.