Room-Temperature Replacement for Ge Detectors—Are We There Yet?

The search for a semiconductor detector capable of room-temperature operation with similar performance to liquid- nitrogen-cooled Ge detectors has been going on for several decades. The main challenge is in achieving the very high degree of spatial uniformity in the detector response that is needed for high-resolution gamma-ray detection. There exist two distinct paths that one can take to meet this goal. One path is to develop materials with near-perfect charge transport properties similar to that of Ge. This requires materials with high mobilities and lifetimes for both electrons and holes, which means extremely low concentrations of electrically-active and carrier-trapping defects. The other path is to employ special device technologies that can provide a highly uniform detector response given the charge transport properties of existing room-temperature semiconductor materials. Many types of device structures and readout techniques have been proposed and investigated, but only a few have the potential to achieve near-Ge spectral performance. We will discuss the basic material and device requirements, the obtainable performance, the state of the technology, and the challenges of these different approaches.