Effect on Electron Beam Treatment of Radio Frequency Sputtered i-ZnO Thin Films for Solar Cell Applications

Intrinsic ZnO (i-ZnO) thin films were prepared using radio frequency (RF) sputtering method with working pressure range of 1 similar to 20 mTorr and treated by electron beam (e-beam) irradiation unit with 300 W of RF power and 2.5 kV of DC power for 5 min. As working pressure increased to 20 mTorr, deposition rate of samples gradually decreased from 0.3 angstrom/sec to 0.18 angstrom/sec and grain size from 23.6 nm to 16.0 nm. After e-beam treatment on RF sputtered i-ZnO thin films with increasing of working pressure, thickness were totally declined by 10% and grain sizes were grown bigger. The electrical properties of e-beam treated samples were remarkably improved to be similar to 10(18) cm(-3) of carrier concentration, 2 similar to 7 cm(2)/Vs of Hall mobility and similar to 10(-1) Omega . cm of resistivity. Transmittance of e-beam treated samples were up to similar to 90% and optical bandgap increased to 3.27 similar to 3.31 eV, resulted from decline of thickness. The better properties of ZnO thin films as a buffer layer in thin film solar cells could be obtained by e-beam treatment method.