Photoemission Analysis Of Chemically Modified Tlbr Surfaces For Improved Radiation Detectors

Device-grade TlBr was subjected to various chemical treatments used in room temperature radiation detector fabrication to determine the resulting surface composition and electronic structure. Samples of as polished TlBr were treated separately with 2% Br:MeOH, 10% HF, 10% HCl and 96% SOCl2 solutions. High-resolution photoemission measurements on the valence band electronic structure and Tl 4f, Br 3d, Cl 2p and S 2p core lines were used to evaluate surface chemistry. Results suggest anion substitution at the surface with subsequent shallow heterojunction formation. Surface chemistry and valence band electronic structure were further correlated with the goal of optimizing the long-term stability and radiation response.