Thin film removal mechanisms in ns-laser processing of photovoltaic materials

In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: a b s t r a c t a r t i c l e i n f o Keywords: Thin films Photovoltaics Solar cell Laser scribing Damage threshold Laser–matter interaction Silicon Copper indium gallium diselenide The removal of thin films widely used in photovoltaics (amorphous silicon, tin oxide, zinc oxide, aluminum, and molybdenum) is studied experimentally using multi-kHz Q-switched solid-state lasers at 532 nm and 1064 nm wavelengths. The processing (" scribing ") is performed through the film-supporting glass plate at scribing speeds of the order of m/s. The dependence of the film removal threshold on the laser pulse duration (8 ns to 40 ns) is investigated and the results are complemented by a multi-layer thermal model used for numerical simulations of the laser-induced spatio-temporal temperature field within the samples. Possible film removal mechanisms are discussed upon consideration of optical, geometrical, thermal and mechanical properties of the layers. Recent years have seen tremendous growth in emerging market economies throughout the world. The resulting rapid increase in resource consumption has driven the cost of energy to unprecedented levels. Accompanying this increased cost was increased interest in alternative energy sources such as photovoltaic (" PV ") devices. And with every surge in the price of oil or gas, there was a corresponding surge in the financial viability of such alternatives. While recently the rate of global economic growth has waned, and the cost of energy has retreated accordingly, interest in solar cell technology remains strong. This is providing a source of continued demand for various support industries such as laser and laser-based system manufacturing. The role of lasers in solar cell device fabrication continues to expand, with processes such as cutting, drilling, scribing, sintering, and annealing all being explored. For the highly-efficient crystalline silicon-based devices (" c-Si "), lasers are most commonly used for edge isolation scribing; but there is also a fast-growing application space with the increased fabrication of more exotic solar cells, such as " emitter wrap through " (via drilling) [1,2] and buried contact (scribing) devices [2,3]. An increasingly popular alternative to c-Si solar cells is thin film photovoltaic (TFPV) device technology, for which the most important laser …