Characterization of Plasma-etched Surfaces of TlBr Crystals for Radiation Detectors

The changes in thallium bromide (TlBr) surfaces induced by plasma etching were characterized by X-ray photoelectron spectroscopy (XPS).A TlBr crystal was grown by the traveling molten zone method with zone-purified material.TlBr wafers were obtained from the crystal.Ar plasma etching was performed on the TlBr wafers.XPS revealed that Tl metal (Tl 0 ) was created in TlBr by the plasma etching.The Tl 0 concentration increased with the irradiation time of the plasma.The net Tl 0 concentrations of TlBr wafers etched by the plasma for 45 and 180 s were 0.7 and 2.6 wt%, respectively.