Thermal Stimulation of Reverse Breakdown in CIGS Solar Cells

Abstract

The underlying mechanisms of the initial stages of hot-spot and therefore defect creation due to reverse breakdown in Cu(In,Ga)S <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\text{e}_{2}$</tex-math></inline-formula> solar cells are not well understood. We test the thesis, that permanent damage is created due to a positive feedback loop of local temperature enhancing the local current and vice versa, resulting in a thermal runaway. We present experiments on reverse stress with simultaneously introducing local heat. Depending on the temperature profile of the introduced heat, the local current density is enhanced and leads to a gain in the local temperature. This feedback loop is shown to lead to reverse breakdown, causing permanent damage.