Investigation of the temperature coefficient of electrical resistance and 1/f noise of laser-annealed amorphous silicon layers

Abstract

In order to investigate whether the performance of microbolometer based heat imaging devices can be improved by excimer laser annealing, we performed several experiments on amorphous silicon layers. Samples with unstructured and structured amorphous silicon layers, which are fabricated with different doping concentrations using a plasma enhanced chemical vapor deposition process, are annealed with Krypton Fluoride excimer laser light at various energy densities. The samples are then electrically analyzed to verify laser annealing. They are also characterized in terms of their electrical conductivity, their temperature coefficient of electrical resistance and their 1/f noise as a function of energy density of the laser. The measurements are used to discuss whether excimer laser annealing is of use to improve microbolometer performance. A threshold value for the energy density at which recrystallization caused by laser irradiation occurs is observed to be 100 mJ/cm2 for both structured and unstructured samples. The temperature coefficient of electrical resistance decreases with increasing energy density from a value of 2%K−1 down to a value of approximately 0.9%K−1.