X-ray sensors based on micro/nano CeO2 segregated AgBiS2 for low dose detection

Semiconductor-based direct conversion X-ray sensors have widespread applications spanning from medical diagnosis to industrial inspection. However, current findings on X-ray detection based on perovskites shows high sensitivity but exhibit large leakage current and poor stability, thus, inhibiting them from commercialization. Highly stable AgBiS2 with large attenuation coefficient (mu = 3.07 g cm(-2) at 70 keV), shows excellent charge conversion due to its higher atomic number (Bi, Z = 83), and density (rho = 7.02 g cm(-3)) was used for X-ray detection. Here, we approach to enhance the net sensitivity of AgBiS2 by tailoring all three parameters by segregating micro/ nanocrystals of cerium oxide (CeO2) at the AgBiS2 grain boundary (GB) region. From the X-ray impinged photocurrent response, substantial GB segregation of n-CeO2 at the AgBiS2 interface leads to improved attenuation and promotes the conversion of multiple scattered X-ray photons into electrons by interacting with the adjacent grains, thus resulting in enhanced photocurrent generation. The sensitivity (S) and noise equivalent dose (NED) ratio were calculated to determine the lowest detectivity of the sensor with less generated noise signals. From these experimental findings, 10 % of n-CeO2 segregation leads to an improvement in the sensitivity of AgBiS2 to 29 mu C mGy(-1) cm(-3).

Automated summary

Semiconductor-based direct conversion X-ray sensors have widespread applications, but current findings on perovskite-based X-ray detection show drawbacks in terms of leakage current and stability. This study aims to enhance the sensitivity of AgBiS2 by segregating cerium oxide micro/nanocrystals, leading to improved attenuation and enhanced photocurrent generation.