PROCESS FOR OBTAINING DIAMOND LAYERS BY GASEOUS-PHASE SYNTHESIS

摘要

The disclosed process for obtaining diamond layers by gaseous-phase synthesis comprises generating a glow discharge of a direct current in a discharge gap between the cathode and the anode in a hydrogen flow. The substrate is heated to a temperature of between 700 and 900 °C, and the diamond layer is deposited on both a dielectric and a conducting substrate at a discharge current density of 0.3-2 A/cm2. The deposition is carried out in a mixture of hydrogen and carbon-containing gas, with a carbon-containing gas concentration of 3-10 % in a gas flow. The graphite phase excess of the discharge in the hydrogen flow is then removed during a period of 5-10 minutes. The carbon containing gas may consist of methane at a 3-8 % concentration, and the substrate may be placed on a grounded or insulated holder out of the discharge gap at a distance of 0.1-5mm from the anode. The anode is made in the shape of an array of molybdenum wire with a diameter of 0.1-1mm and a pitch of 1-3mm. During the deposition process of the diamond layer on the conducting substrate, said substrate may be disposed on the anode. In the case of a deposition process of a diamond layer on a silicon substrate, the natural silicon oxide is first removed from the substrate during a period of 10-20 minutes in the hydrogen flow at a current of 0.3-2 A/cm2. A layer of silicon carbide is created on the substrate by feeding methane at 7-12 % into the gas flow during a period of 10-20 minutes. The diamond layers obtained using this process have a nanocrystalline structure, which produces layers with an emission threshold of up to 3-4V/νm and a current density of over 100mA/cm2. These characteristics enable the diamond layers to be used in the production of flat displays, as well as in electron microscopes, microwave electronics and a number of other applications.