Fine structure on the green band in ZnO

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 inclu des fine structure, which consists mainly of doublets, repeated with a long itudinal-optical-phonon-energy spacing (72 meV). We have developed a vibron ic 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 measure ments. (C) 2001 American Institute of Physics.