Photoconductive and acoustic dual-mode X-ray dose rate detector based on a GaN single crystal

Abstract

A photoconductive and acoustic dual-mode X-ray dose rate detector based on a GaN single crystal was explored in this work, which utilizing the photoelectric and piezoelectric effects of the GaN semiconductor. The detector was fabricated from a bulk GaN single crystal with a resistivity of 10⁷·Ω·cm, and its resonant frequency in the dark condition is 11.5 MHz, with a high quality factor (Q factor) of 1165. Under X-ray irradiation, the bulk conductivity of the GaN single crystal increases allowing the detector to work at the photoconductive mode. Simultaneously, the reduced wave velocity causes a shift in the resonant frequency of the GaN acoustic resonator enabling working at the acoustic mode. Experimental results show that the detector has the responsivities of nC Gy⁻¹·cm^-² and (0.31 ± 0.03) kHz Gy⁻¹ s for the photoconductive and the acoustic modes respectively.