Acceptor Pair‐Bound Exciton Complexes in Semiconductors

Abstract

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'

Excitons bound at interacting acceptors inAlxGa1−Ferreira1, Po2, Ḿonemar3 et al. 1996Phys. Rev. B4010View full textAdd to dashboardCite

“…The complex acceptor BE's have similarities with the undulation spectra observed in some bulk materials such as ZnTe, 6-8 InP, 6 and GaP. 1,2, 8 We do not observe distinct oscillations in our QW structures as has been the case for well-resolved undulation spectra in bulk materials. However, it should be pointed out that it is possible to observe a few additional peaks at the low-energy side.…”

Properties of the main Mg-related acceptors in GaN from optical and structural studies

“…Acceptor bound excitons at high doping level have previously been studied for other compound semiconductors like InP and ZnTe. 29,30 In these cases, a substantial broadening of the ABE peak (corresponding to ABE1 in our case) is observed; it broadens out towards lower energy and there is also some downshift in the mean peak position. The broadening on the low energy side is explained as an effect of the dispersion of the distances in the lattice for interacting acceptor pairs binding the excitons at high doping.…”

“…The broadening on the low energy side is explained as an effect of the dispersion of the distances in the lattice for interacting acceptor pairs binding the excitons at high doping. 29,30 Our observations for the Mg acceptors in GaN with two distinct ABE peaks (ABE1 and ABE2) over the entire doping range, i.e., say 1 Â 10 18 cm À3 to 2 Â 10 19 cm…”

Efficient Incorporation of Mg in Solution Grown GaN Crystals

“…This observation is consistent with efficient compensation of the shallow donors by increased incorporation of the neutral Mg shallow acceptor. 15) Additionally, the emission line associated with the recombination process leaving the donors in the excited states (two electron satellite or 2ES) at 3.449 eV, weakly observed in the spectrum of Ga-polar face, is not present in the PL spectrum of N-polar face. This observation is also consistent with a relatively higher concentration of background shallow acceptor impurities in Npolar face.…”