Control of hydrogen content in the carbon nitride materials and its development to the field emission devices based on the high-resolution laser spectroscopy

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The present study aims to optimize the electric-field-emission property of hydrogenated amorphous carbon nitrides (a-CN_x : H) by controlling the quantity of the hydrogen atoms contained. Carbon nitrides including negligible amount of hydrogen atoms have a property of mechanical hardness. On the other hand, those include hydrogen atoms are, in general, mechanically soft : they have excellent electric-field emission characteristic when the hydrogen atoms are included in the forms of the NH or OH groups. In particular, the hybridized material which consists of the electrically-conducting Al-doped ZnO single-crystal whiskers (Fig.1) coated by the a-CN_x : H or a-CN_x : O : H thin films has a possibility of the FED device. In addition, a-CN_x : H materials containing CH_n(n=1-3) groups have the hydrogen-storage characteristic. Therefore, the control of the hydrogen quantity in the a-CN_x : H or a-CN_x : O : H materials is the key technology to synthesize the materials having the physical p … More roperties hoped.In the present study, carbon nitrides are synthesized by using the plasma enhanced CVD processes by applying the decomposition of cyanides such as BrCN and CH_3CN with the microwave or ECR plasmas of rare gases. In 2004, following studies are made. (1)The decomposition process of BrCN by the microwave-discharged products of Ar and the formation and quenching processes of the precursor CN radicals were investigated based on the laser-induced fluorescence (LIF) spectroscopy and the electrostatic-probe method. The dominant process of decomposition of BrCN is the charge transfer from Ar^+ followed by the BrCN^+-e^-recombination. The dominant quenching process of CN radicals is the reaction with unreacted BrCN. (2)The sticking probability (s) of the CN radicals onto the a-CN_x : H film was determined from the LIF spectroscopy of CN radicals, flow speed, and the weight of the a-CN_x : H film deposited. The s value is in the range of 0.032-0.019 being negatively dependent on the pressure of Ar in the range of 0.3-0.7 Torr. This negative pressure dependence of s can be explained by the reactivity of the CN radicals on the film surface. (3)ECR plasma CVD of the mixed gases of He and BrCN was found to be effective for the synthesis of a-CN_x : O : H with the hydrogen amount in a controlled fashion. Less