Structure of Neutron-Induced Defect Clusters in GaAs MESFETs

摘要

A method is proposed for the structural investigation of defect clusters produced by neutron irradiation of semiconductors. It involves simulation of defect formation and analysis of the distribution of point defects within individual clusters. The method enables one to characterize point-defect aggregations in a cluster in terms of size, separation, and arrangement. It could be applied to advanced devices based on a nanoscale heterostructure. Point defects produced by neutron irradiation of semiconductors are known to form clusters as a result of the cascaded nature of atomic displacements initiated by neutron impact. Each cluster consists of one or more subclusters, i.e., dense aggregations of secondary displaced atoms. In GaAs, defect clusters generated by 1.5-MeV neutrons typically contain two to ten stable subclusters about 10 nm in diameter, which may overlap. Defect subclusters have individual space-charge regions; these scatter hot electrons and combine to impede the motion of cold electrons, with the electron energy measured relative to the thermal energy.