REACTIVE MAGNETRON SPUTTERING OF AL DOPED ZNO FILMS - DEPENDENCE OF OPTICAL, ELECTRICAL, COMPOSITIONAL AND STRUCTURAL-PROPERTIES ON DEPOSITION CONDITIONS

Aluminium doped ZnO layers have been prepared by reactive DC magnetron sputtering from Zn:At(2wt%) targets onto unheated substrates (Si, glass, pyrolytic carbon). In dependence on the 0, partial pressure in the argon sputtering gas there exists a narrow process window around 5% to 10% p(O2)(p(Ar) + p(O2)) which yields transparent, low resistant layers. Lower O2 partial pressures yield metallic-like, opaque, and highly resistant layers. Higher oxygen partial pressures lead to transparent, but highly resistant ZnO layers. Layers with the highest conductivity (5 x 10(-4) OMEGA . cm) and transmission (90%) have a stoichiometric ratio Zn/O of 1.0 and the largest grains (40 nm) as has been measured by RBS and XRD. By comparing the metallurgical Al content (RBS) with the carrier concentration (Hall and conductivity measurements) we get an overall electrical activation of aluminium of about 35%.