CZT Radiation Detectors for Homeland Security Applications

High Z detectors are needed for efficient detection of X-rays having energies greater than about 15keV. Traditionally the only technology that satisfies this need is the cryogenic germanium detector or scintillation counters. The energy resolution of HPGe detectors is below 0.5% at 662keV, but room-temperature band-gap of germanium is only 0.74 eV, and thermal charge generation must be suppressed by cooling the material to near-liquid-nitrogen temperatures. So there has been an enormous push to develop a room temperature detector that can provide the energy resolution of HPGe detectors At present, scintillators are the core component of most room temperature instruments. They offer a room temperature energy resolution higher than 7% at 662keV. Cadmium Zinc Telluride (CZT) is the most promising high-Z semiconductor material for high-resolution, room-temperature gamma radiation spectrometers to use in homeland-security applications. The latest developments on CZT as radiation detectors are presented.