Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1814990 | Physica B: Condensed Matter | 2007 | 4 Pages |
Abstract
EL2 is the ubiquitous native defect in crystalline GaAs grown by a variety of different techniques. It has been proposed to be a doubly charged deep-level center with two states having distinct energy levels in the band gap. While the singly charged state has been the subject of many experimental studies and is, therefore, well established, the doubly charged state has only been occasionally alluded to in the literature. This paper provides evidence for a dominant inadvertent deep level in p-type GaAs most likely to be the doubly charged state of the EL2 center. Deep-level transient spectroscopy (DLTS) has been applied to characterize epitaxial layers of p-type GaAs grown on p+ GaAs substrates by low-pressure metal organic chemical vapor deposition (LP-MOCVD). A pronounced peak is observed in the majority carrier (hole) emission deep-level spectra. Thermal emission rate of holes from the corresponding deep level is found to exhibit a strong electric field dependence, showing an increase of more than two orders of magnitude with an increase of the electric field by a factor of â¼2. The thermal activation energy for this level is found to vary from 0.29 to 0.61Â eV as the electric field is varied from 2.8Ã105 to 1.4Ã105Â V/cm. Direct pulse-filling measurements point to a temperature-dependent behavior of the hole capture cross section of this level. We identify this inadvertent deep-level defect, commonly observed in p-type GaAs grown by a variety of different methods, with the doubly charged state of the well-known AsGa antisite related defect, EL2.
Related Topics
Physical Sciences and Engineering
Physics and Astronomy
Condensed Matter Physics
Authors
Nazir A. Naz, Umar S. Qurashi, Abdul Majid, M. Zafar Iqbal,