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Semiconductor Physics, Quantum Electronics & Optoelectronics. 2009. V. 12, N 4. P. 406-411.
Thin silicon solar cells with SiОх /SiNx Bragg mirror
rear surface reflector
1Taras Shevchenko Kyiv National University, Faculty of Radiophysics,
build. 5, 2, Academician Glushkov prospect, 03022 Kyiv, Ukraine
E-mail: ivancko@gmail.com
Abstract. Bragg reflectors consisting of sequence of dielectric layers with a quarter
wavelengths optical thickness are promising to create solar cells of third generation.
SiО х /SiN x Bragg mirror (BM) at the backside of textured multicrystalline silicon solar
cells was fabricated by PECVD method. BM with 9 bi-layers was optimized for the
maximum reflectivity within the wavelength range Δλ = 820...1110 nm. The maximum
measured reflectivity is approximately 82 %. Measured reflectivity values were
compared with the simulated ones by using the transfer matrix. Effect of parameters for
pyramids of several types on the total reflectivity of BM deposited on textured silicon
surface was simulated. Enhancement of light absorption and external quantum efficiency
in the longwave part of the spectrum (λ > 940 nm) was observed, and it was explained as
increase of the photon absorption length. The influence of BM on passivation of SC rear
surface was explored. The cell back contact was formed by Al diffusion through BM to
the μc-Si wafer and promoted by a pulsed laser. For SC with BM, the efficiency 13.75 %
is obtained comparatively with efficiency 13.58 % for SC without BM.
Keywords: silicon solar cell, Bragg mirror, numerical simulation.
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