Development of lead chalcogenide nanocrystalline (NC) semiconductor ionizing radiation detectors

Nanocrystalline (NC) semiconductor materials exhibit exploitable properties - such as tunable energy band gap, and charge carrier multiplication - which arise due to the strong quantum confinement effect. If the highly uniform multiplicities of excitons can be developed across macroscopic NC samples, then one can potentially quench the statistical counting noise associated with charge carrier creation in the bulk material. Lead chalcogenide (PbSe and PbTe) NC particles of different sizes and shapes were synthesized by changing the reaction conditions and their characterization is reported. Closely packed NC assemblies of PbSe were formed by drop-casting the NC dispersion on various metal contacts, making use of its self-agglomerating nature. Current-voltage (I-V) characteristics of the NC assembly were studied to evaluate its property as an NC assembly diode, followed by an alpha particle impingement experiment from the Am-241 source. The viability and continuing empirical challenges of using lead chalcogenide NC materials as a basis for the detection of ionizing radiation are discussed.