The nanocrystalline diamond films in this research were deposited on metal/silicon substrates using CH4/H2/Ar=1:10:94 gas mixture by microwave plasma chemical vapor deposition (MPCVD) system. Prior to deposition, 300 nm of thickness for Chromium(Cr),Titanium(Ti),Aluminum(Al) metals with work functions of 4.5,4.33 and 4.28 eV were sputtered onto p-type (100) Si substrate, respectively. Diamond powder abrasion pretreatment technique was used to enhance the nucleation. The field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) were used to analyze the surface morphologies. Micro-Raman Spectroscopy, 532 nm laser beam of 2 mW and beam size of 5µm, was performed to study the qualities of the nanocrystalline samples.
It is found that the nanocrystalline diamond is p-type. From the Raman analysis, the peak at 1140 cm-1, 1480 cm-1, 1332 cm-1 and 1560 cm-1, corresponding to the signatures of the nanocrystalline diamond, diamond and the presence of graphite G-band. The surface roughness of the nanocrystalline diamond films were measured approximately 80 nm. The thickness was about 180 nm. The size and the thickness were both suited to the field emission studies. The field emission measurements were preformed by a high vacuum measuring system with a pressure of 10-7 Torr. The distance between the anode and cathode is approximately 100µm. It was found that the turn on field of the field emission for Cr,Ti and Al were 3.0, 3.5 and 4.9 V/µm, respectively. It was suggested that the lower turn on field of the field emission for the diamond/ higher work function metal structure since electrons are easier for the injection.
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