Local mode spectroscopy and photohyphen;induced effects of oxygenhyphen;related centers in semihyphen;insulating gallium arsenide

摘要

Vibrational absorption of semihyphen;insulating Ohyphen;containing GaAs samples has been investigated under highhyphen;resolution spectroscopy at low temperature and many sharp lines due to localized modes have been observed. Some of them, between 714 and 730 cmminus;1had already been ascribed to some (Ga,O)hyphen;related center having features common with the vacancyhyphen;oxygen defect in silicon, but a new state related to this center, giving a local mode near 713 cmminus;1is reported here for the first time. Another new lowhyphen;frequency mode at 604 cmminus;1is also reported, involving probably nitrogen or more likely oxygen bonded to two nexthyphen;nearesthyphen;neighbor Ga atoms. The attribution of new modes in the 950ndash;1400 cmminus;1spectral region to complexes involving oxygen, arsenic, and eventually impurities with 100percnt; isotopic abundance is discussed. The effects of nearhyphen;infrared illumination on the observation of the (Ga,O)hyphen;related modes between 713 and 730 cmminus;1and on a new mode at 983 cmminus;1have been studied. Tentative explanations based either on metastability or on photohyphen;induced changes of the charge states of the centers are proposed. These results seem to show that in GaAs, oxygen decorates native centers and that this kind of study could provide a clue to their understanding.