Influence of Disordered Regions on the Optoelectronic Properties of Heterostructures with Ge/Si Nanoislands Irradiated with Fast Neutrons

Abstract

It is shown that the concentration оf disordered regions (radiation-induced defect clusters) formed during the irradiation of semiconductors by neutrons with a fluence of 1013–1015 cm–2 is just an order of magnitude less than the bulk concentration of Ge/Si nanoislands in modern multilayer heterostructures with their planar arrays. The elastic strain of the crystal lattice around the disordered regions is several times less than that around the Ge/Si nanoislands, which determine their optoelectronic properties. The irradiation of modern heterostructures with arrays of Ge/Si nanoislands by neutrons with a fluence of 1015 cm–2 means that up to 40% of nanoislands fall within the space charge area of many disordered regions. It is concluded that degradation of the optoelectronic properties of heterostructures with Ge/Si nanoislands irradiated with neutrons is mostly due to the influence of the energy levels of radiation-induced defects in the band gap and electric field of disordered regions on the charge carrier kinetics near nanoislands.