Vacancies and Dominant Electrically Active Defects in Bulk Semi-Insulating GaAs

Positron Annihilation techniques have been used to investigate two important defects that occur naturally in semi-insulating (SI) Gallium arsenide. The growth and assessment of SI GaAs and the application of PA to defect analysis of this important material are reported

Electrical techniques for the measurement of deep states

AbstractWhen point defects, either intrinsic (such as vacancies or interstitials) or extrinsic (most impurities with the exception of shallow donors or acceptors) are introduced into a semiconductor, they can result in the occurrence of ‘deep states’. These are electronic levels that are not normally ionized at room temperature, but can affect both carrier concentrations and minority carrier lifetime. The purpose of this review is to provide an outline of the techniques that are commonly used to characterize deep defect states in terms of their electrical properties

New EL2 structural model based on the observation of two sequential photoquenching processes

The EL2 photoquenching kinetics has been studied by measuring the transmittance of a 1.05 μm laser beam as a function of time. The photoquenching curve presents two time constants that we associate to a two-stage transition through an intermediate state to the final metastable state. This was verified by measuring the temperature dependence of the transmittance with the sample prepared in a stage of partial photoquenching. Besides being also metastable, we show that the intermediate state has an optical absorption-cross section that is temperature dependent. In order to explain the existence of such a state, we propose a new structural model for the EL2 in which the motion of an arsenic atom finds two metastable positions after photoexcitation. Our model is based on a mixture of features derived from the models proposed by Chadi and Chang [1] and more recently by Fukuyama et al. [2]. Copyright EDP Sciences/Società Italiana di Fisica/Springer-Verlag 2005