Study on light scattering of rf sputtered ZnO:Al thin films as a front electrode of amorphous silicon thin film solar cells

Al-doped ZnO thin films as a front electrode of silicon pin solar cells were prepared on the glass substrates by rf magnetron sputtering in which working pressure and substrate temperature were controlled precisely. After film deposition, the films were etched by dilute acid solution to obtain the textured surfaces. Material properties of the deposited films were investigated by various analytical methods and especially the light scattering for the textured films was determined by optical scattering parameters-haze and angular distribution function (ADF). The as-deposited ZnO:Al thin films show good electrical resistivity and optical transmittance of about 4.5 × 10^-4 ¿·cm and above 80% in the visible wavelength range, respectively. After etching process, surface texture and light scattering are affected significantly by the deposition parameters and etching time. The optimized optical properties and light scattering of the films are obtained at working pressure of 0.5mtorr, substrate temperature of 135°C and etching time of 45 sec.