DC Ionization Conductivity of Amorphous Semiconductors for Radiation Detection Applications

DC ionization conductivity measurements were used to characterize the electrical response of amorphous semiconductors to ionizing radiation. Two different glass systems were examined: a chalcopyrite glass ( CdGe_xAs₂; for x = 0.45-1.0) with a tetrahedrally coordinated structure and a chalcogenide glass ( As₄₀Se_(60-x)Te_x; where x = 0-12 ), with a layered or three dimensionally networked structure, depending on Te content. Changes in DC ionization current were measured as a function of the type of radiation (alpha or gamma ), dose rate, applied field, specimen thickness and temperature. The greatest DC ionization response was measured with CdGe_0.85As₂ at -40degC from an alpha source (which is the first reported result for radiation response from an amorphous chalcopyrite semiconductor). Avalanche gain was observed in As₄₀Se₆₀ with exposure to alpha radiation at fields ges 7times10³ V/cm. These results demonstrate the potential of these materials for radiation detection applications.