On the Dynamical Behaviour of Excitons in CdS Single Crystals. I. Correlation between Intrinsic Excitonic Absorption and Emission

Voigt, J.; Spiegelberg, F.

doi:10.1002/pssb.19680300227

Cited by 34 publications

(17 citation statements)

References 13 publications

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“…With respect to the exciton-phonon interaction, the results of photoconductivity experiments agree with those of the absorption and emission [13] measurements :…”

Section: Discussionsupporting

confidence: 79%

“…Recently, the existence of the two types of space charge layers a t the surface of CdS was also suggested by Weber [20] from measurements of surface photoconductivity. The second and third assumption is supported by the results of investigations of the exciton interaction processes in CdS discussed in [12] and, in detail, in Part I [13].…”

Section: Discussionmentioning

confidence: 71%

“…The third assumption, tightly connected with the second one, is directly proved in the emission experiments (see Part I [13]), in which is found that a quasi-thermal equilibrium exists between the formation of excitons from electron-hole pairs and their dissociation, and that the excitons are thermalized.…”

Section: Discussionmentioning

confidence: 91%

“…The crystals as well as the arrangement used in the absorption measurement have been described already in [12] and [13]. I n the photoconductivity measurements platelets (3 x x 0.4 x 0.2 cm3) grown from the vapour phase with evaporated I n contacts were used.…”

Section: Experimental Arrangementmentioning

confidence: 99%

“…Second, no quantitative results exist about the interaction processes of excitons in CdS that determine the lifetime of optically excited excit0ns.l) I n two preceding papers by Gutsche and Voigt 1121 and Voigt and Spiegelberg [13] exciton-phonon interaction processes in CdS are discussed on the basis of measurements of excitonic absorption and emission. I n view of these results it was very interesting to reinvestigate the problem of photoconductivity in CdS induced by primary generation of excitons.…”

Section: Introductionmentioning

confidence: 99%

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On the Dynamical Behaviour of Excitons in CdS Single Crystals. II. Correlation between Intrinsic Excitonic Absorption and Photoconductivity

Voigt

Ost

1969

Physica Status Solidi (b)

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An investigation is made of the excitation spectra of photoconductivity of CdS single crystals in the region of the fundamental absorption edge from 77 O K to room temperature. The results are compared with those of excitonic absorption measurements. On the basis of conclusions about the dynamical behaviour of excitons, equally drawn from absorption, emission, and photoconductivity measurements, a model is proposed of the photoconductivity in the region of exciton transitions, which explains the correlation between the exciton absorption and photoconductivity. This model involves that the diffusion length of the excitons don't exceed that of the ambipolar electron-hole pair diffusion.Anregungsspektren der Photoleitung von CdS-Einkristallen werden im Bereich der Grundgitterabsorptionskante zwischen 77 O K und Zimmertemperatur nntersucht. Die Ergebnisse werden mit MeBergebnissen der Exzitonenabsorption verglichen. Basierend auf den SchluBfolgerungen iiber das dynamische Verhalten von Exzitonen, die iibereinstimmend aus Absorptions-, Emissions-und Photoleitfahigkeitsmessungen gezogen werden, wird ein Modell der Photoleitfahigkeit im Bereich der Exzitonenubergange vorgeschlagen, welches den Zusammenhang zwischen der Exzitonenabsorption und der Photoleitfahigkeit erklart. Das Modell schlieBt ein, daB die Diffusionslange der Exzitonen nicht groBer ist als die fur die ambipolare Diffusion von Elektron-Loch-Paaren.

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“…With respect to the exciton-phonon interaction, the results of photoconductivity experiments agree with those of the absorption and emission [13] measurements :…”

Section: Discussionsupporting

confidence: 79%

Section: Discussionmentioning

confidence: 71%

Section: Discussionmentioning

confidence: 91%

Section: Experimental Arrangementmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

On the Dynamical Behaviour of Excitons in CdS Single Crystals. II. Correlation between Intrinsic Excitonic Absorption and Photoconductivity

Voigt

Ost

1969

Physica Status Solidi (b)

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The influence of chemisorption of oxygen on the luminescence of cds single crystals

Heine

Wandel

1973

Phys. Stat. Sol. (a)

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Besides a decrease of the luminescent intensity and the photocurrent in CdS single crystals in an oxygen atmosphere a considerably stronger dependence of the luminescent ntensity and of the photocurrent on the excitation intensity can be observed than with a chemisorbate-free surface. An expression is derived that enables to determine the intenisity dependence of the exciton radiation from the known intensity dependence of the red luminescence and of photocurrent. Further it is shown that the quantum efficiency of the excit,on annihilation P e X C depends on the concentration of the chemisorbed oxygen particles and consequently on the excitation intensity.Nehen einer Abnahme der Lumineszenzintensitat und des Photostromes bei der Chemisorption von Sauerstoff kann bei CdS-Einkristallen in Stluerstoffatmosphare eine wesentlich starkere Abhangigkeit der Lumineszenzintensitat und des Photostromes von der Anregungsintensitat beobachtet werden als bei chemisorbatfreier Oberflache. Es wird ein Ausdruck hergeleitet, der es ermoglicht, die Intensitatsabhangigkeit der Exzitonenstrahlung aus den bekannten Intensitatsabhlngigkeiten von roter Zentrenlumineszenz und Photostrom abzuleiten. Fernerhin wird gezeigt, dal3 die Quantenausbeute der Exzitonenannihilation , W C von der Konzentration der chemisorbierten Sauerstoffteilchen und damit von dcr Anregungsintensitat abhangig ist.

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Effect of heat treatment on the photoelectric properties of class I CdS single crystals

Bragagnolo

Böer

1974

Phys. Stat. Sol. (a)

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The photoelectronic properties of virgin CdS platelets, sublimed and cooled in an N,-H,S atmosphere, were altered by heat treatment in ultra-high vacuum. The untreated crystals showed a strongly structured spectral distribution of the photoconductivity (SDP) a t liquid nitrogen temperature (LNT), having maxima (Class I) or minima (Class 11) in coincidence with maxima of the intrinsic exciton absorption in addition to several characteristic peaks attributed to bound exciton excitation. Changes in the room temperature and LNT SDP of Class I crystals, occurring upon treatment below 200 "C, are interpreted in terms of thermal desorption of oxygen from the surface and evaporation of a thin layer of excess cadmium. Continuing cadmium evaporation and bulk sensitization caused by dissociation of intrinsic defect associates are assumed to be responsible for the irreversible changes observed upon treatment above 200 O C : a change of Class I crystals into Class 11, and increase in photosensitivity and a decrease in the LNT green-edge emission. A model for Class I and Class I1 photoconductivity involving an electron lifetime that changes with distance from the crystal surface is presented. Die photoelektronischen Eigenschaften von jungfriiulichen CdS-Einkristallen, die in einer N,-H,S-Atmosphare sublimiert und abgekiihlt wurden, werden durch Temperung im Ultrahochvakuum veriindert. Die ungetemperten Kristalle zeigen ein stark strukturiertes Spektrum der Photoleitfiihigkeit bei der Temperatur des fliissigen Stickstoffes und haben Maxima (Klasse I) oder Minima (Klasse 11), die mit den Maxima der Absorption von Gitter-Exzitonen koinzidieren zusiitzlich zu mehreren charakteristischen Maxima, die gebundenen Exzitonen zugeschrieben werden. Veranderungen der spektralen Verteilung der Photoleitfahigkeit von Klasse-I-Kristallen, die nach einer Temperung unterhalb von 200 "C auftreten, werden als Folge der thermischen Desorption von Sauerstoff an der Oberfliiche und der Verdampfung einer diinnen Schicht von ffberschulkadmium gedeutet. Weitere Verdampfung von Kadmium und Volumen-Sensibilisierung, die durch die Dissoziation von Eigendefekt-Assoziaten verursacht wird, sind vermutlich verantwortlich fur irreversible Veranderungen, die nach einer Temperung bei iiber 200" erfolgen, namlich eine Umwandlung von Klasse-I-in Klasse-11-Kristalle, eine Erhohung der Photoleitfahigkeit und eine Verringerung der grunen Kantenemission bei Stickstofftemperaturen. Ein Modell fur Klasse-I-und Klasse-11-Photoleitfiihigkeit, das die Lebensdauer von Elektronen als Funktion des Abstandes von der Oberfliiche enthalt, wird vorgeschlagen.

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On the Dynamical Behaviour of Excitons in CdS Single Crystals. I. Correlation between Intrinsic Excitonic Absorption and Emission

Cited by 34 publications

References 13 publications

On the Dynamical Behaviour of Excitons in CdS Single Crystals. II. Correlation between Intrinsic Excitonic Absorption and Photoconductivity

On the Dynamical Behaviour of Excitons in CdS Single Crystals. II. Correlation between Intrinsic Excitonic Absorption and Photoconductivity

The influence of chemisorption of oxygen on the luminescence of cds single crystals

Effect of heat treatment on the photoelectric properties of class I CdS single crystals

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