In this thesis the relationship between plasma chemistry and energetics and thin film properties was investigated for an Al cathodic arc discharge. A virtually monoenergetic beam of single charged Al ions was generated at pressure distance products higher than 128 Pa.cm. In the literature Al cathodic arc discharges always contained a high energy tail which made it difficult to analyse the influence of plasma parameters on thin film properties. Thermalization of the cathodic arc discharge is expected at high pressure distance products. What made this work particularly interesting is that the thermalization effect was observed at conditions where the deposition rates were still high (about 1nm/s). It was shown that crystalline films containing a- and ?-Al2O3 phases could be grown using cathodic arc discharges containing monoenergetic single charged Al ions. This is a prerequisite for a meaningful study of the influence of plasma parameters (such as ion flux and energy) on film formation and properties.