Shallow Acceptors in Cadmium Telluride

Abstract

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.

Investigation of the origin of deep levels in CdTe doped with Bi

“…Three emissions are detected, which can be assigned to typical acceptor defects or impurities present in CdTe, such as V Cd , Na, and Ag. [17][18][19][20][21][22] Thus, changes from pure ͑D 0 −X͒-type spectrum for Bi1 sample, to a ͑A 0 −X͒-type spectrum for samples Bi4 and Und indicate that the donor involved in the first case is important in the electrical compensation. This shallow defect is FIG.…”

Identification of Ag-acceptors in 111Ag/111Cd doped ZnTe and CdTe

“…The A Ag 1 line at 1.5885 eV, the A Ag 2 line at 1.5010 eV, and the donor-acceptor pair (DAP Ag ) band at 1.491 eV are observed [8]. Again, the intensities of these PL lines are shown to be enhanced by diffusion of Ag into CdTe, and the observed acceptor level is assigned to Ag Cd defects [9].…”

Carrier density and lifetime for different dopants in single-crystal and polycrystalline CdTe

“…32 Similarly, for pX and sX CdTe with ion-implanted or diffused Cu, resonantly excited luminescence, infrared absorption, and PL assign the Cu Cd level to 145-150 meV with a zero-phonon DAP transition at 1.45 eV. 26,27,32,[35][36][37][38][39][40] The emergence of the zero-phonon DAP peak at 1.453 eV and replicas for Cu + Te in Fig. 1(c) is consistent with the formation of 145-150-meV Cu Cd acceptors.…”

“…1(d) cannot be attributed to the Cu Cd or Cu i sites based on recent experimental and theoretical capture cross section estimates. 37,52 So a different Cu defect is the most plausible explanation, and improved activation could increase lifetime. In addition to increasing lifetime and hole density, it is necessary to establish a stable defect chemistry.…”