Abstract
In this thesis, we discuss more fully the metastable growth of carbon in two fields: low pressure deposition of diamond films and the preparation of a-C:H films. Their physical properties are examined in detail by the measurement systems. The a-C:H coatings are far easier to grow than diamond films and have many pragmatic uses. Under proper deposition conditions, very hard, chemically inert and optical transparent films can be prepared. These films are also called the diamond-like carbon films (DLC), because their properties are similar to diamond. Otherwise, soft polymer-like carbon films (PLC) are obtained. These films show intense visible photoluminescence (PL) in which the spectral range can be varied by controlling the carbon content in the films. The results from the PL investigation show that the PL is sensitive to laser irradiation time, when the laser power is greater than 1 kW/cm2. CVD diamond films inherit with stable and intrinsic negative electron affinity (NEA) surfaces. NEA surfaces allow electron emission at low electric fields (20V/μm) and room temperature. Diamond electron emitters are also called cold electron emitters as compared with traditional hot electron emitters. Therefore, diamond emitters have attracted much attention recently for vacuum microelectronics devices and field emission displays (FED). However it is not clear that the field emission characteristics of diamond and what factor of CVD diamond controls the optimized field emission current. It is the object of this work to investigate in detail the electron field emission from doped diamond surfaces. We emphasize how NEA diamond surfaces can be removed and re-established by various surface treatments. The emission current density can be enhanced from 0.8μA/cm2 to 100μA/cm2 at an electric field of 20 V/μm by hydrogenation treatment. Thus, the field emission characteristics of diamond films can be optimized for practical applications by hydrogenation. The field emission current of diamond surfaces varies manifestly with temperatures in this experiment. Fowler-Nordheim equation is conventionally used to portray the results of the field emission from diamond surfaces. However, F-N equation fails to explain the temperature effects. Therefore, the field emission equation for semiconductor surfaces at low field will be derived in this thesis. Expectantly, the experimental results of the field emission characteristics and temperature effects are in consistent with said equation.