The Preparation N Type Doped Nitrogen Nanometer Diamond Thin Film And Research Of S-band Microwave Field Emission Performance

Diamond arises people’s attention because of its outstanding physical and chemical properties, in particular the development of the CVD diamond thin film technology, which attempts to obtain the diamond thin film of specific properties by using different impurities to dope it, is of great significance in both the field of electron beam source, and semiconductors.Adopt the microwave plasma chemical vapor deposition(MPCVD) method to prepare different doped N- type nitrogen nanodiamond thin films(NCD) deposited on single-crystal silicon substrate. Use field emission scanning electron microscopy(FESEM), laser Raman spectroscopy, atomic force microscopy(AFM) and X-ray diffraction to analyze the surface morphology and structure of the samples. Results show that in the Ar-CH4-C3H6N6 system, with the increase of reaction pressure and CH4 concentration, both the particle size and surface roughness of the thin film firstly increase and then decrease. What’s more, the SP2 contents in the thin film also rise. Moreover, with the increase of the reaction temperature, the particle sizes decrease, while the SP2 contents decrease at first and then increase. In addition, as the Ar contents increase, both the particle size and the diamond content in the film decrease.Then test and analyze the field emission properties of doped N-type NCD thin film samples which have been prepared in the conditions of different CH4 concentration, on the width of 3.2 μs pulse, maximum amplitudes up to 85V/um microwave field pulses, and 10-5 Pa vacuum environment. Go on to compare the FESEM and Raman changes before and after the microwave field emission. Results demonstrate that doped N-type NCD thin film prepared with low CH4 concentration has better field emission properties. And the F-N curves of all samples are in a straight line, which indicates their emission follows the classical field emission electron law. Under 67.7 V/m electric field, the maximum emission current density reaches 144.8 m A/cm2. The surface morphology and phase composition of the thin film change slightly, which manifests the prepared doped N-type NCD thin films are of good stability under the condition of microwave field emission.