Fine structure on the green band in ZnO

Abstract

An emission band at 2.4 eV, called the green band, is observed in most ZnO samples, no matter what growth technique is used. Sometimes this band includes fine structure, which consists mainly of doublets, repeated with a longitudinal-optical-phonon-energy spacing ͑72 meV͒. We have developed a vibronic model for the green band, based on transitions from two separate shallow donors to a deep acceptor. The donors, at energies 30 and 60 meV from the conduction-band edge, respectively, are also found from Hall-effect measurements.

Photoluminescence and damage recovery studies in Fe-implanted ZnO single crystals

“…Recently, the vibronic-assisted green band was explained as an overlap of phonon DAP-assisted transitions between two shallow donors, with E D1 ϭ30 meV and E D2 ϭ60 meV and a deep unknown acceptor. 27 These donor activation energies are common in ZnO samples, E D1 being recently related with hydrogen. 28 Annealing treatments in air in ZnO single crystals are known to induce changes in the green emission band.…”

Correlated d ferromagnetism and photoluminescence in undoped ZnO nanowires

“…2͑b͒, DLE ͑green emission band͒ shows fine structures, which repeat with a longitudinaloptical-phonon-energy spacing ͑ϳ72 meV͒ and are associated with the transitions involving shallow donors ͑oxygen vacancies͒. 17 Fig. 2͑d͒ shows the temperature-dependent PL spectra of NW-1, illustrating the evolution of the dominant DLE from RT down to 5 K.…”

Multicolor Luminescence from Semiconductor Nanocrystal Composites Tunable in an Electric Field

“…There are several models to explain the blue-green and red emission in ZnO. The most acceptable models assume that the defect centers responsible for green luminescence are the singly ionized oxygen vacancy centers (Vanheusden et al, 1996a(Vanheusden et al, , 1996b or donor-acceptor level transitions (Egelhaaf & Oelkrug, 1996;Reynolds et al, 2001;Studenikin et al, 2002). The acceptor level (Zn vacancy) is located 2.5 eV below the conduction band edge (Bylander et al, 1978;Egelhaaf & Oelkrug, 1996), while the donor level (oxygen vacancy) is known as a shallow level at 0.05-0.19 eV, leading to an emission band centered around 508-540 nm.…”