Influence of Local Mechanical Stress on Mono- and Polycrystalline Silicon-Based p-n Junction Under Illumination

In this article, the effect of local mechanical stress on the properties of monocrystalline and polycrystalline silicon-based p-n junctions under illumination is studied and analyzed experimentally and theoretically. Results from the experiments showed that when the local mechanical force was increased from 4 N to 20 N, the short-circuit current of the monocrystalline silicon-based p-n junction changed nonlinearly from 24 mA to 43 mA, and that of the polycrystalline silicon-based p-n junction changed linearly from 14.7 mA to 16.7 mA. Experimental results shows that the ideality coefficient of the p-n junction based on monocrystalline silicon decreased from 1.274 to 0.807 and that of polycrystalline from 1.274 to 1.102. Therefore, when the mechanical force applied on monocrystalline silicon increased, the dominant recombination changed from Shockley-Read-Hall to Auger. On the other hand, in polycrystalline silicon, the dominant Shockley-Read-Hall recombination did not change due to the grain boundaries. So, it means that mechanical force causes the narrowing of the band gap of the silicon not increasing of number of recombination centers. When mechanical force increases from 4 N to 12 N, fill factor of monocrystalline increased by 5.75% and that of polycrystalline decrease by 1.1%. In the range of 4 N and 20 N mechanical force, saturation current of monocrystalline and polycrystalline silicon p-n junction changed from
$8~\mu \text{A}$
to
$41~\mu \text{A}$
. and
$22~\mu \text{A}$
to
$97~\mu \text{A}$
, respectively.