Optical investigations of the undulation spectrum of GaP:N:Zn

A systematic study of acceptors incorporated by diffusion is carried out on refined melt-grown ZnTe. The properties of five substitutional acceptors are investigated by low-temperature photoluminescence. Since the binding energy of excitons on neutral acceptors is almost unaffected by the central cell potential, the neutral acceptors are identified by the two-hole transitions which give accurate values of acceptor ionization energies. The two dominant acceptors "b" at 61 meV and "a" a t 149 meV are identified as Lizn and CUZ,,, respectively, while the hole binding energies on Nazn, Bgz,, and Auzn are established as 62.8, 123, and 272 meV, respectively. These experiments show that all the relatively shallow acceptors involve impurities and not stoichiometric defects.Une Ctude systematique des accepteurs introduits par diffusion a 8t6 faite sur ZnTe. Les propriCtes de cinq accepteurs sont CtudiCes en photoluminescence. Comme 1'6nergie de liaison des excitons sur les accepteurs neutres n'est pas affectee par le potentiel de cellule centralc, les accepteurs sont identifies gr&e aux transitions deux-trous qui donnent une valeur tr&s precise de la profondeur de chaque niveau. Les deux accepteurs dominants: "a" ti 149 meV e t "b" B 61 meV sont attribuCs au lithium e t au cuivre en site zinc alors que les niveaux accepteurs introduits par Na, Ag e t Au sont respectivement ti 62.8, 123 e t 272 meV. L'ensemble de ces experiences montre que tous les accepteurs peu profonds mettent en jeu des impuretCs e t non des dbfauts de stoechiometrie.

Section: Resultsmentioning

confidence: 99%

Optical identification of substitutional acceptors in refined ZnTe

Magnéa

Bensahel

Pautrat

et al. 1979

“…In GaP the "undulation spectrum" l) 85X, 38041 Grenoble Cbdex, France. relative to isoelectronic centres seems to have the same physical origin [6]. I n fact, when the impurity concentration is high enough, formation of impurity clusters dominates the properties of the material.…”

Section: Introductionmentioning

confidence: 88%

“…A more careful analysis suggests that we must consider the interaction of three or more neutral acceptors rather than only a n isolated pair. SW [6] showed that these interactions result in a broadening of the discrete line corresponding to an isolated pair. Thus the overlap of the discrete lines gives a smooth shape t o the spectra.…”

Section: Theoretical Bandshapementioning

confidence: 99%

“…Our purpose here is to describe the evolution of the PBE line for different acceptors, when the acceptor concentration increases. We use the model of Street and Wiesner (SW) [6] who explained the undulation spectrum in GaP doped with N and Zn in considering exciton localization on N-Zn pairs. Our experiments are performed in ZnTe doped with Li, Na, Cu, Ag, and Au, which are well-known acceptors in this material [7, 81.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Acceptor Pair‐Bound Exciton Complexes in Semiconductors

Molva¹,

Magna²

1980

The evolution of the principal bound exciton (PBE) line, for bound exciton-neutral acceptor@) complex(es), between low ( 5 l0ls acceptor concentrations in semiconductors, is studied. Photoluminescence experiments are performed in ZnTe, for the five wellknown acceptors Li, Na, Ag, Cu, Au and for several doping levels. High concentrations provide an asymmetric broadening with undulations and a shift to lower energies of the PBE line. Semiempirical calculations are made for the neutral acceptor pair-bound exciton complex. I n ZnTe good agreement is obtained with experiment. The calculations demonstrate that the empirical relation A E ( R ) = E, exp (-R/R0)3 is a good and simple analytical approximation of the bound exciton localization energy shift, when the exciton is bound on a neutral acceptor pair, with a pair separation R . These calculations permit to evaluate the energy shift of the PBE line maximum for acceptors in highly doped semiconductors.Une etude de 1'8volution de la raie excitonique principale resultant de ]'annihilation d'un exciton lie A, un (des) accepteur(s) neutres(s), a CtB faite, en fonction de la concentration des accepteurs dans le semiconducteur. Les experiences de photoluminescence sont faites dans ZnTe, pour les accepteurs Li, Na, Ag, Cu et Au, qui sont bien connus et pour differentes concentrations N A lo1*Quand la concentration est &levee, on observe un Blargissement asymetrique avec des ondulations, et un decalage vers les basses energies de la raie excitonique principale. Des calculs semi-empiriques ont 6t6 faits dans le cas d'un exciton piegg sur une paire d'accepteurs neutres. Les resultats ont 6tB compares avec l'expkrience dans ZnTe, et un bon accord a At6 obtenu. Nos calculs dbmontrent que, la relation empirique AE(R) = E,, exp (-R/&J3 est une bonne et simple approximation analytique du decalage calcule de 1'6nergie de liaison de I'exciton quand il est pikg6 sup une paire d'accepteurs avec une separation R . Le resultat de nos calculs nous permettent de prevoir le decalage en knergie du maximum de la bande des ondulations pour les accepteurs, quand le matkriau est trbs dope. and high (> lo1'

“…This phenomenon is well known, and has been observed in Gal? [15] and also for all the acceptors in ZnTe [16, 171. In fact, when the acceptor concentration increases, the mean distance between acceptor sites decreases, and so bound excitons are delocalized on several interacting When N , increases, the peak energy shifts to higher energies (Fig. 2, curves b and c).…”

Section: As-grown and Annealed Cdtementioning

confidence: 99%

Shallow Acceptors in Cadmium Telluride

Molva

Chamonal

Pautrat

1982

147

The photoluminescence spectroscopy of undoped CdTe crystals provides information on two acceptors which are the main contaminants of as-grown crystals. These acceptors called y and z have their respective ionization energies a t 147 and 108 meV. A complete series o f two hole replicas iu observed for y and only one for z. These acceptors are believed to be due to Cu and A@; impurities. Backdoping experiments with Li and Na give rise to new transitions. From the conduction bandacceptor level transitions, t,he ionization energies are respectively obtained to 57.8 and 58.8 meV. In the case of Li, some extra-lines are tentatively identified as phonon interacting two-hole transitions.La spectroscopie de la photoluminescence de CdTe non dope fournit des informations sur deus nccepteurs qui sont des contaminants du matkriau brut de croissance. Ces accepteurs, appeIBs y et z ont leurs Bnergies d'ionisation respectivement A 147 et 108 meV. Une serie complBte de repliques a deux trous a 6th observee pour y et seulement une replique pour z. Ces accepteurs sont probablement dus aux impuretks Cu et Ag. Des experiences de dopage avec Li et Na donnent naissance a de noovelles transitions. A partir des recombinaisons bande de conduction-niveau accept.eiir, les dnergies d'ionisation ont kt6 respectivernent obtenues 5'7,s e t 58,5 meV. Dam le cas du Li, des ruies supplhmentaires sont attribuees it une transition ? i , deux trous, perturbke par une interaction avec des phonons.