Room temperature ionizing radiation detectors using colloidal PbSe QDs

Abstract

In this study, we demonstrate that colloidal PbSe quantum dots (QDs) can be a viable active material for room temperature semiconductor radiation detectors (RTSDs). QDs were synthesized with two different recipes and ligand exchanged with NH4SCN and 1-octanethiol when needed. When the QDs were fully dried, simple pellet architectures were manually pressed and I-V sweeps were performed to determine material resistivity. By varying QD diameters and ligand combinations the pressed pellet resistivity could be tuned between 104–1013Ω cm. When exposing devices to 133Ba radiation, full energy deposition peaks in pulse height spectra proved difficult to obtain. Sensitivity to the radiation could be ascertained once material resistivity reached ≥108Ω cm. Several devices demonstrated that resolution (peak full width half max over peak centroid) at 81 keV could be achieved with values of 4.75% and 5.98%. We found that performance was highly dependent on the contact point of a given superstructure. A comparison to other studies using colloidal QDs as an RTSD materials indicate that our results show similar performance. Further, our results are an improvement in performance compared to recent single crystalline RTSD materials such as CdSe.