Optimal bandgap variants of Cd1−xZnxTe for high-resolution X-ray and gamma-ray spectroscopy

We show that the trade-off between noise and charge generation statistics in Cd1−xZnxTe leads to an optimal band gap of approximately 2.0 eV at room temperature. This implies a ZnTe fraction of approximately 0.7–0.8. We show that for X-rays and relatively low energy gamma-rays Cd0.2Zn0.8Te theoretically offers a significant potential improvement in energy resolution over Cd0.9Zn0.1Te even if compensation of shallow levels is less complete and carrier lifetimes are an order of magnitude lower for the higher x variant. We also show that these calculations are consistent with observed detector performance reported by many workers over a large period of time.