Sammendrag
Zinc Oxide is a promising material for reducing the price of solar cells since its high abundance and low cost makes it attractive in replacing the more commonly used and more expensive Indium Tin Oxide as a transparent front contact. Using co-sputtering of Zinc Oxide
and Silicon, highly transparent (>80% transmittance in visible range) and low-resistive ( ~0.001 ohmcm) films have been prepared. Annealing of the films in air at temperatures ranging from 550 C to 1050 C leads to an improved crystal quality, but the heat treatment is seen to have an adverse effect on the electrical characteristics of the films. Both the electrical characteristics and the crystal quality of the samples improve with Si doping up to a concentration of 1.5 +/- 0.5%. Above this concentration, these properties degrade. The films have been deposited on different substrates, and it is found that deposition on crystalline Silicon and glass produce films of good electrical and crystal quality while deposition on amorphous Zinc Oxide leads to films of poor quality. Although this substrate leads to films of low crystal quality (close to amorphous), the films still have satisfactory electrical and optical properties. It is also found that Silicon and Aluminium addition to the films leads to lower grain sizes suggesting that Silicon and Aluminium act as mobility inhibiting surfactants. Attempts to manufacture Silicon nanocrystals embedded in a Zinc Oxide matrix have been made but they proved to be unsuccessful. This is most likely due to the low formation energy of Silicon Dioxide.