DOUBLE-LAYER PLATES FROM SYNTHETIC DIAMOND SINGLE-CRYSTALS DOPED WITH NITROGEN FOR HIGH-TEMPERATURE n-TYPE SCHOTTKY DIODES

Abstract

For the first time, a vertical Schottky diamond diode with an electronic type of conductivity was manufactured and investigated on the basis of a two-layer single-crystal plate of synthetic diamond doped with nitrogen, in which a thin working layer of low-nitrogen-doped diamond was grown by the chemical vapor deposition method homoepitaxially on a heavily nitrogen-doped substrate cut in the plane {100} from a single crystal grown by the method of high-pressure-high-temperature growth on the seed. The concentration of nitrogen in the form of single substitution atoms (C-centers) in the working layer, grown by the chemical vapor deposition method, was 0.5 ppm, the layer thickness was 10 μm, the thickness of the substrate with a nitrogen concentration of ~ 200 ppm was 400 μm. 6 Schottky contacts with a diameter of 0.6 mm were made by magnetron sputtering of a platinum layer with a thickness of 200 nm through a contact mask. A rectangular ohmic contact was made to the substrate also by magnetron sputtering through a contact mask of a 5 nm thick Ti layer, followed by high-temperature annealing in vacuum to form titanium carbide, and subsequent deposition of a Pt layer with a thickness of 200 nm to prevent oxidation of titanium carbide in air. The current-voltage characteristics of the manufactured diodes were studied at a bias range of (-200 V) – (+200) V at temperatures up to 650 °C. The opening voltage of the manufactured diode structure is ~ 30 V, the maximum current of each diode in the open state reaches 1 mA at U = 200V, while the reverse current at T = 525-650 °C does not exceed 0.1 µA. The highest rectification coefficient value was ~104.