In dependence on the deposition conditions, amorphous carbon films cover a broad range of different structures and correspondingly varying properties. Apart from the directly determined sp3 content (e.g. by EELS or XPS), relevant properties allow to assess the realized film qualities (see Sect. 2.1.1). Table 15.1 summarizes orienting ta-C values for minimum sp3 content (50% per definition) and maximum achievable sp3 content (around 85%).