Fabrication and characterization of Heteroepitaxial Diamond Radiation Detector with Ti/Pt/Au electrodes

Diamond radiation detector with $\mathrm{Ti} / \mathrm{Pt} / \mathrm{Au}$ electrodes was fabricated from a heteroepitaxial diamond grown on a Ir/sapphire substrate. The diamond substrate measured $4 \mathrm{~mm} \times 4 \mathrm{~mm} \times$ 0.5 mm was cut and polished. The $\mathrm{Ti} / \mathrm{Pt} / \mathrm{Au}$ electrodes were deposited on the polished surfaces by spattering method. Thin gold wires were bonded between the electrodes and a printed circuit board. The device was irradiated with high-energy X-rays from a radiation therapy treatment system at room temperature. The X-rays at 6 MV were irradiated for 12 seconds. The total amount of absorbed dose was about 1 Gy. The device exhibited linear response corresponding to the applied bias voltage between the electrodes of the front and back sides. The higher bias voltage resulted in higher charge amount and less standard deviation. The charge amount per unit volume was about 14000 times higher than that of a conventional ionization chamber at maximum. The results indicated that the heteroepitaxial diamond detector with $\mathrm{Ti} / \mathrm{Pt} / \mathrm{Au}$ electrodes had a capability for high energy X-ray radiation detection with high sensitivity and high reproducibility.