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Studies the mechanism for low-temperature photoluminescence emissions in gallium arsenide structures by molecular beam epitaxy. Major characteristic properties identical in both structures and epilayers; Dependence on the excitation power and measurement temperature.

Investigates the mechanism for thermal quenching of luminescence in silicon germanide/silicon structures grown by molecular beam epitaxy. Effect of post-growth thermal annealing; Reduction of grown-in nonradiative defects; Demonstration of post-growth hydrogenation; Contribution of nonradiative recombination channels.

Investigates the nonradiative defects in silicon (Si) and Si germanide/Si heterostructures grown by molecular beam epitaxy. Introduction of defects by ion bombardment and low surface adatom mobility; Application of the optically detected magnetic resonance technique; Efficiency of defects as nonradiative channels for carrier recombination.

Abstract: Defect formation in ZnO epilayers grown by molecular beam epitaxy (MBE) is studied by employing optical characterization techniques such as photoluminescence (PL) and optically detected magnetic resonance (ODMR). Excess of oxygen during the growth was found to cause an appearance of the PL peak at around 3.338eV, which indicates that the corresponding defects are predominantly formed in O-rich ZnO. On the other hand, non-stoichiometry during the growth was singled out as the main factor facilitating formation of defects involved in the yellow PL emission band peaking at around 2.17eV. Several magnetic-resonance active defects are revealed via monitoring this emission and their magnetic-resonance signatures are obtained. [Copyright &y& Elsevier]

New dilute nitride Ga1−xAlxNyP1−y alloys grown by gas-source molecular beam epitaxy have been studied by the optical detected magnetic resonance technique. Two paramagnetic defect centers with an effective electron spin S=1/2 were observed and shown to involve Ga interstitials (denoted as Gai-A and Gai-B), both exhibiting the characteristic hyperfine (HF) structure from the two Ga isotopes. The HF interaction is shown to be nearly isotropic and rather strong, providing evidence for an A1 symmetry of the electron wave function highly localized at the Ga atom. We tentatively attribute Gai-A and Gai-B to the interstitial sites surrounded by group-III and group-(V and III) atoms, respectively. [Copyright &y& Elsevier]