Temperature dependent photoluminescence studies in CsI:Tl films with varying thicknesses

Abstract

Films of Tl doped CsI in the 10 nm to 3 µm thickness range were deposited on silicon substrates using the physical vapor deposition technique under vacuum conditions. The films exhibited a columnar growth behavior with a preferential orientation along 〈200〉. The photoluminescence (PL) properties of the deposited films were studied in the 77–300 K temperature range and found to be significantly different compared to the bulk CsI:Tl single crystal. In the excitation process, the unperturbed self trapped exciton (STE) excitation of the host was found to be dominant in films of lower thicknesses and direct excitation in “A” band of Tl+ and STE perturbed by the Tl+ gradually evolved with increasing film thickness. At low temperatures, the PL from a 1 µm thick CsI:Tl film revealed an unperturbed STE excitation at 5.9 eV with a corresponding emission around 3.7 eV that vanishes near room temperature. This suggests that the energy transfer from the host excitons to the activator site (Tl+) is weak at low temperatures in the CsI:Tl films.

Photostimulated luminescence in Tl-doped NH4Br translucent ceramics synthesized by SPS

“…Compared to reported spectra of Tl-doped halides, the luminescence peaks at around 400 and 580 nm were attributed to 3 P 1 → 1 S 0 transitions of Tl + and the off-center STEs localized around Tl + , respectively. [42][43][44] By increasing Tl concentration, the luminescence peak around 400 nm looked slightly shifted to a longer wavelength. As seen in Fig.…”

Performance assessment of CsI(Tl) screens on various substrates for X-ray imaging

“…Fedorov et al [5] fabricated CsI(Tl) layers on LiF and glass substrates, and examined their scintillation efficiency, crystal structure and spatial resolution. Shinde et al [6] deposited CsI(Tl) films on silicon substrate in the thickness range between 10 nm and 3 µm , and focused on the temperature dependent *Supported by National Key Scientific Instrument and Equipment Development Project (2011YQ03011205, 2013YQ03062902) and Key Program of the National Natural Science Foundation of China (U1332202) 1) E-mail: qinxb@ihep.ac.cn Submitted to 'Chinese Physics C' photoluminescence of CsI(Tl) films. Yao et al [7] fabricated CsI(Tl) films on glass substrate covered by a pre-deposited CsI layer, and concluded that the performance could be improved when films were prepared on substrates with special treatment.…”