X-ray sensing characteristics of a spin-coated n-ZnO film.

We report X-ray sensing characteristics of a thick n -ZnO film. The film was synthesised using a spin-coating method from a specific solution of zinc acetate dihydrate, ethanol and triethanolamine (TEA). An X-ray diffraction analysis confirmed that the film has crystalline nature having hexagonal crystal structure. The thickness of the film was determined using a scanning electron microscope (SEM) and found to be ∼29–45 µm. An analysis of absorption spectrum revealed the optical bandgap of the sample to be 3.45 eV. The current-voltage (I-V) characteristics were recorded under dark condition and X-ray (at 30 keV, 8 mA) illumination condition. The resistivity of the sensor under the dark condition at bias voltage 2.0 V was found to be 6.4 × 107 Ωcm and that under the X-ray illumination, 4.8 × 106 Ωcm. The sensor shows high signal-to-noise ratio within 0.5–6.0 V bias voltage. The analysis of response time of the sensor shows a rise time of 0.87 s and fall time of 1.08 s at 3.0 V bias voltage. The sensor is also found to be visible blind within 370–700 nm. A quantitative analysis of photoresponse characteristics with dose rate reveals that the sensor shows sublinear response between 0.015 and 0.220 Gy/s. The sensitivity for 0.220 Gy/s dose rate at a bias voltage of V = 6.0 V is found to be ∼ 155.1 μ C. G y − 1 c m − 3 . The sensor shows a pseudo rectifying type I-V characteristic under dark condition. The I-V characteristic under dark condition was further analysed quantitatively using space-charge-limited current (SCLC) model. [Display omitted] • X-ray sensing characteristics of a thick (∼29 – 45 µm) n -ZnO film is reported. • A pseudo rectifying type I-V characteristic is observed under dark condition. • The sensor shows high signal-to-noise ratio within 0.5–6.0 V bias voltage • The sensitivity for 0.220 Gy/s dose rate is found to be ∼ 155.1 μ C. G y − 1 c m − 3 . • The sensor shows rise time of 0.87 s and fall time of 1.08 s at 3.0 V bias voltage. [ABSTRACT FROM AUTHOR]