X-ray sensitivity of small organic molecule and zinc cadmium sulfide mixture layers deposited using thermal melting technique

Abstract

Recently the spin-coating technique was employed to deposit X-ray sensitive layers of polymer mixture with high atomic number nanoparticles. Here, we demonstrate thermal melting method for deposition of X-ray absorptive thick layers. For investigations of X-ray photocurrent the thermally melted layers of various content of N,N,N′,N′-Tetra(p-tolyl) benzidine (TPTB) and Zinc Cadmium Sulfide (ZnCdS) powder have been formed between two ITO-glass and Al-glass substrates. Under X-ray flux of 3.5×109s−1cm−2 the estimated integral dose rates were 2.5mGy/s for pure layer, 38.0mGy/s for 15wt%, 59.8mGy/s for 25wt%, 80.4mGy/s for 35wt% and 108.7mGy/s for 50wt% of ZnCdS in layers. An introduction of ZnCdS particles led to higher conductivity of the layers where the values of reverse bias current estimated up to 75nA/cm2. In the sample with 50wt% ZnCdS, the measured photocurrent (Iph=2.8nA) was almost ten times higher than that in the layer with 15wt% of ZnCdS (0.18). Under low X-ray flux (Φ) Iphvs.Φ dependences deviate from linear while above 2×109s−1cm−2 linear dependences are obtained for all samples. The highest sensitivity is estimated for 50wt% of ZnCdS layer reaching 50nC/mGy/cm3.