AES, photoemission and work function study of the deposition of Cs on (100) and (111)B GaAs epitaxial layers

Rodway, D. C.

doi:10.1016/0039-6028(84)90169-9

Cited by 39 publications

(7 citation statements)

References 18 publications

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“…This constant value seems to be specific to surfaces prepared by sulfide passivation, as an immediate decrease of the work function is generally observed. 9 For a distinct surface preparation procedure, a relatively small value of the barrier has been found for the clean surface, with an increase in the initial stages of cesium adsorption to a position near midgap. 23 In this last case, the measured work function reveals both the increase of the surface barrier, and the change of affinity due to electron transfer to the surface.…”

Section: Work Functionmentioning

confidence: 98%

“…For RT adsorption, ͑top panel͒ this variation is very similar to results published before. 8,9 The cesium concentration saturates after an exposure time of 90 min, at which we assume that 1 ML of cesium is deposited on the surface. The sticking coefficient is constant up to a 50 min exposure, which corresponds to coverage ratio of 0.7 ML.…”

Section: A Experimental Setup and Proceduresmentioning

confidence: 99%

“…Auger spectroscopy has shown that the cesium coverage saturates after a given exposure, which is generally taken as a reference for 1 ML of cesium on the surface. 8,9 The cesium sticking coefficient is reduced by a factor of 2-3 at approximately 0.5 ML. This coverage has been shown to correspond to the maximum of the photoemission current, and to the minimum of the work function.…”

Section: Introductionmentioning

confidence: 99%

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Formation of the Cs/GaAs(001) interface: Work function, cesium sticking coefficient, and surface optical anisotropy

Kierren¹,

Paget²

1997

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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We have studied at room temperature (RT) and at near liquid-nitrogen temperature [low temperature (LT)], the adsorption of cesium on clean gallium-rich GaAs(001) prepared by sulfide passivation, and annealing in ultrahigh vacuum. We monitor the optical transitions of gallium surface dimers, using reflectance anisotropy spectroscopy (RAS), and the changes of work function and cesium sticking coefficient. The clear correlations between these three quantities allow us to distinguish three adsorption phases: (i) At LT and up to 0.7 ML coverage, cesium adsorption induces a decrease of the RA signal, which perfectly corresponds with the work function decrease. The RA decrease is, therefore, caused by the surface dipole due to charge transfer from cesium to the solid. (ii) At RT, for a coverage smaller than 0.15 ML, both the RA signal and the work function change are different from their LT behavior, so that a distinct adsorption process occurs. This indicates that cesium diffuses to specific surface sites at which the bonding is different. (iii) At a coverage larger than 0.7 ML, and independently on adsorption temperature, no charge transfer to the solid occurs, since no change of RA spectrum and work function is observed. The cesium sticking coefficient is reduced by a factor of 2. Comparison with results obtained on As-decapped GaAs(001) shows the similarity of the formation of the interface for the two surfaces. However, the results are clearer for the surface prepared by sulfide passivation, which seems to be of higher quality.

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Section: Work Functionmentioning

confidence: 98%

Section: A Experimental Setup and Proceduresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Formation of the Cs/GaAs(001) interface: Work function, cesium sticking coefficient, and surface optical anisotropy

Kierren¹,

Paget²

1997

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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“…Despite the fact that there is an extensive literature on the role of caesium and oxygen for NEA, and a reduced work function on multi-alkali and GaAs substrates, there are still disagreements and uncertainties as to how the sensitization is eective. It is certain that for GaAs the emission is strongly crystal face sensitive, with the {111B} face having an escape probability as high as 50% [24,25]. A monolayer of Cs is eective but eciency decreases with further layers.…”

Section: Electron Emissionmentioning

confidence: 99%

Photocathodes—past performance and future potential

Townsend¹

2003

Contemporary Physics

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Light detection and imaging at very low intensities, even down to individual photon detection, has been made possible by the development of photomultiplier and imaging tubes. They have two main components: a photocathode detector and an electron multiplication section, but throughout their long history their performance has been limited by the response of the photocathodes. Reappraisal of the underlying science of cathode preparation emphasizes that they are still performing well below their full potential. The reasons for this are discussed and some indications of how improvements could be made are suggested. Since many of the potential advances are within the scope of current technology it is certainly feasible to achieve enhancements in performance by factors of two to ten across the blue to near-infrared spectral range. Higher improvement factors are implied but will be dicult to realize in the normal spectral range for wavelengths below 1 mm. Signi®cant gains in sensitivity, and perhaps in response speed, will open many new opportunities for low light level sensors and the prediction is that they will be an enabling technology for developments in biological and medical applications, among others.

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“…Numerous surface studies of Cs on the (100) and (110) surfaces of GaAs have been performed using Auger spectroscopy, Cs adsorption energies as a function of Cs dosage. 8,9,[12][13][14][15][16][17][18][19] However, a complete theoretical understanding of these characteristics and differences is still lacking.…”

Section: Introductionmentioning

confidence: 99%

Ab initiostudies of Cs on GaAs (100) and (110) surfaces

et al. 2015

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GaAs with an atomic monolayer of Cs is one of the best known photoemissive materials. The results of density functional theory calculations of Cs adsorption on the GaAs(100)-(4×2) galliumterminated reconstructed surface and the GaAs(110) surface are presented in this work. Coverage of up to 4 Cs atoms/nm 2 on GaAs surfaces has been studied to predict the work function reduction and adsorption energies accurately. The high mobility of Cs atoms on the (110) surface allows formation of ordered structures, whereas the low mobility of Cs of the (100) surface causes amorphous growth.

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AES, photoemission and work function study of the deposition of Cs on (100) and (111)B GaAs epitaxial layers

Cited by 39 publications

References 18 publications

Formation of the Cs/GaAs(001) interface: Work function, cesium sticking coefficient, and surface optical anisotropy

Formation of the Cs/GaAs(001) interface: Work function, cesium sticking coefficient, and surface optical anisotropy

Photocathodes—past performance and future potential

Ab initiostudies of Cs on GaAs (100) and (110) surfaces

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