Photoemission analysis of chemically modified TlBr surfaces for improved radiation detectors

Abstract

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%SOCl 2 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.

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

“…In the combination of elements detected after Ar etching, the possible chemical states of Tl are Tl 0 , Tl 2 O, Tl 2 O 3 , and TlBr, corresponding to energies of 117.1, 119.1, 118.6, and 119.2 eV, respectively. (13) Since the energy of Tl 0 is close to the measured energy of the subpeak, it was concluded that the subpeak represents Tl 0 . The main Tl 4f peak was considered to be mainly TlBr; thus, we expressed it as Tl (TlBr).…”