Preparation Of Wide Band Gap & Super-hard Thin Films By Chemical Vapor Deposition

In thesis, the researches and development on dielectric barrier discharge chemical vapor deposition (DBD-CVD), diamond like carbon(DLC) thin films, boron nitride(BN) thin films were reviewed. The history, theory and applications of DBD and DBD-CVD were comprehensively summarized. The structure, properties, applications and preparation of DLC and BN thin films were particularly analyzed and discussed. DBD is a typical non-equilibrium high-pressure ac gas discharge, it can be operated at normal pressure, it can be operated at low pressure too. At low pressure mold, DBD can produce high-energy plasma. Therefore, the substrate temperature will be reduced when DBD is applied on CVD, and the deposition rate is also increased. DLC film is a kind of very important wide band gap & super-hard semiconductor thin films due to their attractive properties which are close to those of diamond, e.g. extreme hardness, low static and dynamic coefficient of friction, high electrical resistivity, high thermal conductivity, and chemical inertness. Furthermore, DLC films can be easily deposited on large area substrates with diameter of above 500 mm at room temperature. BN thin is also a kind of promising HI-V compound semiconductor, it is a material which exhibits high hardness, wide band gap (6.4 eV), good thermal conductivity, and chemical inertness. High quality, large area DLC, BN thin films were deposited, which prepared for the subsequent fabrication of devices.A set of stable equipments were set by the basic DBD theory, and DLC thin films were deposited by DBD-CVD. Furthermore, the structure and properties of DLC films were studied. In order to obtain the optimum process parameters, the effects of process parameters were discussed. The structure and properties of DLC thin films deposited on different substrates using the optimum process parameters were studied, and the N-doped DLC thin films were also discussed. BP_xN₁-x thin films were deposited on quartz substrates by Hot Filament assisted Plasma Enhanced Chemical Vapor Deposition (HF-PECVD), the effects of substrate temperature on the structure and properties of BP_xN₁-x thin films were studied, and the effect of P on the modulation of the band gap of the BP_xN₁-x was also discuss. The potential applicationof BP_xN₁-x thin films on Liquid Crystal Light Valve(LCLV) was analysed.The effect of deposition parameters on the structure and properties of DLC thin films was studied firstly. With increasing the deposition voltage, the content of sp3C in the DLC thin films increased, the roughness of the thin films decreased. With increasing the deposition frequency, the content of sp3C in the DLC thin films increased, the roughness of the thin films decreased. With decreasing the deposition pressure, the content of sp3C in the DLC thin films increased, the roughness of the thin films decreased. At the optimum parameters ( 12kV, 20kHz, lOOPa), the films obtained is smooth, higher sp3C content, high hardness, good adhesion on substrate, and high transmittance at visible and near infrared light region. DLC thin films were successfully deposited on different substrates. The quality of DLC films on metal substrate is better, and there properties excel the DLC films on non-metallic substrate. The DLC film on AI substrate is same as the non-metallic substrate because there is thick oxide-layer on Al. N-doped DLC thin films were also successfully deposited, and N-doped DLC thin films has very little inter-stress and good adhesion.The BP_xN₁-x thin films were successfully deposited on commercial quartz substrates by HF-PECVD. The substrate temperature affected the structure of the films very much, with increasing substrate temperature, the crystalline of BP_xN₁-x films became better, when the substrate temperature reached 400, the films obtained are polycrystalline and texture-growth, the surface of the thin films is grain-like and dispersing incompact. With increasing the flux of PH3 during deposition, the content of P in the films increased, it can be controllable doped. With increasing the...