Boron Nitride Thin Films Of The Hot Filament Assisted Plasma-enhanced Chemical Vapor Deposition Method And Its Uv Sensitivity Performance

Boron nitride(BN) is an advanced semiconductor material with outstanding physical and chemical properties, such as high thermal conductivity, outstanding thermal stability, chemical inertness and wide band gap which up to 6.0eV and hence has the potential for the high-temperature, high-power and radiation resistivity electronic applications. Recently there has been an extensive worldwide effort to synthesize BN films and investigate ultraviolet sensitive properties of BN, which has an important significance to the development of ultraviolet band detecting.In the thesis, BN films were deposited using hot-filament and r.f. plasma enhanced chemical vapour technique (HF-PECVD) on monocrystalline silicon and quartz glass substrates under the low temperature. The effects of ultrasonic pre-treating of substrates, temperature, r.f. power and hydrogen on the deposition of BN films were discussed systematically. It can be concluded that the combined intensity between films and substrates is improved by ultrasonic pre-treating of substrates which also accelerates the nucleation of BN. In addition, it can be found out that deposition temperature and r.f. power are key factors in the synthesis of films, in some extent, improving temperature and power is beneficial to the deposition of films. However, cubic BN will be formed in higher temperature and power, which weakens the combined intensity between films and substrates. During the deposition of films, hydrogen facilitates the forming of cubic BN, but cubic BN will also weaken the combined intensity of films and substrates. In order to prepare high quality films, appropriate temperature and r.f. power should be selected, and moreover, the content of the hydrogen need be controlled.Ternary compound BNxPi-x films of quality are deposited and the ultraviolet absorbance characteristics of BNXP,-X films were investigated in the thesis, too. With the quantity of phosphorus dopant, the optical bandgap modulation of BNxPi \ is achieved successfully. In addition, the combined intensity of BNXP,-X films and substrates was enhanced by depositing the buffer layer.Based on these above, the practical realization of BNxPi-x film applied in the ultraviolet band detecting device - ultraviolet liquid crystal light valve is discussed. The experiments and theory analyses prove that BNxPi-x film is a suitable candidate for ultraviolet liquid crystal light valve.