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

•Mixture layers of organic molecules and ZnCdS were deposited using thermal melting.•Response of I–V characteristic to an X-ray photon flux were measured.•Photocurrent of layers with 50 wt% ZnCdS was ten times higher than in 15 wt% layers.•The highest sensitivity (50 nC/mGy/cm3) was for layers with 50 wt% of ZnCdS.•The photocurrent dependence on X-ray photon flux for mixture layers was linear.

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 × 109 s−1 cm−2 the estimated integral dose rates were 2.5 mGy/s for pure layer, 38.0 mGy/s for 15 wt%, 59.8 mGy/s for 25 wt%, 80.4 mGy/s for 35 wt% and 108.7 mGy/s for 50 wt% 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 75 nA/cm2. In the sample with 50 wt% ZnCdS, the measured photocurrent (Iph = 2.8 nA) was almost ten times higher than that in the layer with 15 wt% of ZnCdS (0.18). Under low X-ray flux (Φ) Iph vs. Φ dependences deviate from linear while above 2 × 109 s−1 cm−2 linear dependences are obtained for all samples. The highest sensitivity is estimated for 50 wt% of ZnCdS layer reaching 50 nC/mGy/cm3.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slide