An X-ray diffraction and electron-microscopic study of the influence of gamma radiation on multilayer AlGaAs/InGaAs/GaAs heterostructures

Abstract

The influence of gamma radiation on multilayer AlGaAs/InGaAs/GaAs transistor heterostructures has been studied by means of X-ray diffraction analysis and transmission electron microscopy. It was found that irradiation with doses exceeding ∼3 × 107 rad leads to destruction of the GaAs layer on the surface of these structures. An irradiation dose of 108 rad significantly deteriorates the surface planarity, with the surface roughness reaching values of several nanometers. In addition, dislocations are formed in the cap layer of the structure. Such a behavior of the cap layer may be due to the existence of an oxide layer on its free surface and to the possible chemical reactions, induced by gamma radiation, between atoms of the cap layer and free radicals formed in the oxide and in the ambient atmosphere. No noticeable changes in the structure and composition of the thin InGaAs channel layer occur at doses lower than 108 rad.