Photoemission and optical constant measurements of a Cesium Iodide thin film photocathode

Pandit, Triloki; Rai, Rakesh; Gupta, Nikita; Jammal, Nabeel; Singh, B. K.

doi:10.1016/j.nima.2014.11.085

Cited by 9 publications

(3 citation statements)

References 17 publications

(15 reference statements)

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“…The optical absorption of reflective and semitransparent CsI thin films has been obtained by C. Lu et al [16], P. Maier et al [37], T. Boutboul et al [38] and Triloki et al [15]. We found that our results are having good match with them.…”

Section: Optical Properties Of Csi Thin Filmssupporting

confidence: 85%

“…Cesium Iodide (CsI) thin films are widely used as photoelectron converters in particle physics and medical imaging experiments [1,2] due to its high quantum efficiency (QE) in the ultraviolet (UV) spectral range [3][4][5][6], a high secondary electron emission (SEE) yield [7,8], a relatively high stability in air among other alkali halides material [9] and its capability to operate in a stable way with gaseous detectors [10,11]. In the recent past, a lot of research work has been done in order to enhance its QE [12][13][14] and several groups have made progress in this respect and a quantum efficiency of about 35-40% at 150-160 nm has been reported for a 500 nm CsI thin film [15,16]. Under humid-free gas atmosphere, CsI thin film has been coupled successfully with a multiwire proportional chamber (MWPC) and various micropattern gas detectors such as gas electron multiplier (GEM), thick gas electron multiplier (THGEM) [4,17], etc.…”

Section: Introductionmentioning

confidence: 99%

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Structural and optical properties of CsI thin films: Influence of film thickness and humidity

Jammal

Rai

Pandit

et al. 2018

Physica B: Condensed Matter

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Structural and optical studies have been performed on the thermally-evaporated "as-deposited" and "humid air aged" CsI thin films. The structural analysis for both "as-deposited" and "humid air aged" films shows a well-oriented peaks position of (110) and (220) lattice planes with a compressive stress in the films. The crystal quality has been investigated through the structural parameters. The increase in peak intensity as well as sharpness with film thickness implies the improvement of crystallinity. The optical absorbance of CsI films has been analyzed in the wavelength range of 190 nm -900 nm in order to estimate the band gap energy of the films. Slater's model has also been used to explain the degradation of band gap energy with the increase in crystallite size. been tested successfully under liquid xenon atmosphere for its use in dark matter search experiment [21]. The detectors used for these experiments generally work in two modes; reflective (opaque) and semitransparent mode. The Quantum Yield (QY) of reflective films has been observed to be higher in comparison with the semitransparent films. This is because the semitransparent films have a small escape length (L≤ 10 nm) [16]. Also, it has been revealed that the reflective films have more chemical stability against the moisture compared to the semitransparent films [17].Keeping these facts in mind, the main issue related to CsI photocathode is the aging which causes a degradation in the photoemission properties and thus limits their life. In order to develop and optimize large area photocathodes based detector, the study of the optical and structural properties of the "as-deposited" and "aged" CsI photocathodes is ultimately required. In literature, there are several studies on CsI ageing, but its mechanism does not have a clear understanding yet. A. S. Tremsin et al. [23] have used TEM technique to study the structural properties of polycrystalline CsI thin film of 100 nm thickness under the impact of humid air and UV irradiation. M. A. Nitti et al. [24] have examined the bulk structure and the surface of freshly and humid air exposed 100 nm CsI film by XRD and XPS measurements. Recently, Triloki et al. [25] have studied the structural properties of thermally-evaporated CsI thin films of different thicknesses by using XRD and TEM techniques. C. Lu and K.T. McDonald [16] have previously reported the optical properties of freshly CsI thin films up to 31 nm thickness. This work is an extension of the previous works, where we have systematically studied the structural and optical properties of semitransparent and reflective CsI thin films grown under similar vacuum-environment in case of "as-deposited" and "humid air aged". Experimental Details Deposition of CsI thin filmsThe deposition of reflective (500 nm and 300 nm) and semitransparent (50 nm and 30 nm) CsI thin films was done in a stainless steel 18" diameter spherical vacuum chamber. Prior to the deposition process, the substrates were cleaned by treating with distilled water, acetone, and alcohol to...

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Section: Optical Properties Of Csi Thin Filmssupporting

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Structural and optical properties of CsI thin films: Influence of film thickness and humidity

Jammal

Rai

Pandit

et al. 2018

Physica B: Condensed Matter

Self Cite

View full text Add to dashboard Cite

show abstract

“…Many materials are clearly not suitable: metals have too low a quantum yield even with surface modifi-cation, 8 while alkali halides, such as CsI with h z 40%, have high work function and are hence solar blind. 9 Conventional high-performance bialkali photocathodes can give work function approaching 1.5 eV and h as high as 40%. 10 Although these materials are normally used in vacuum and considered vulnerable to surface contamination, it has been demonstrated that K-Cs-Sb photocathodes can operate in atmospheric pressure gaseous photomultipliers with h = 10%-20% in the range 300-400 nm.…”

Section: Is Photoelectric Solar Power Feasible?mentioning

confidence: 99%