  Distributed bragg reflectors (DBRs) consisting of ZnO and amorphous silicon
(a-Si) were prepared by magnetron sputtering method for selective light
trapping. The quarter-wavelength ZnO/a-Si DBRs with only 6 periods exhibit a
peak reflectance of above 99% and have a full width at half maximum that is
greater than 347 nm in the range of visible to infrared. The 6-pair reversed
quarter-wavelength ZnO/a-Si DBRs also have a peak reflectance of 98%.
Combination of the two ZnO/a-Si DBRs leads to a broader stopband from 686 nm to
1354 nm. Using the ZnO/a-Si DBRs as the rear reflector of a-Si thin film solar
cells significantly increases the photocurrent in the spectrum range of 400 nm
to 1000 nm, in comparison with that of the cells with Al reflector. The
obtained results suggest that ZnO/a-Si DBRs are promising reflectors of a-Si
thin-film solar cells for light trapping.
