Materials for photodetectors based on intersubband transitions in GaN/AlGaN quantum dots

摘要

The electron states and optical properties of a dense ordered array of quantum dots (QDs) based on GaN and AlN crystals of the wurtzite (w) structure have been studied by the pseudopotential method, with the hexagonal symmetry, deformations, and internal electric fields accurately taken into account. It is shown that the minimum of the first electron miniband at the center of the Brillouin zone of the QD superlattice originates from a state of the central Gamma(1) valley of the conduction band of the binary crystals, while the higher levels are associated with the states of the U side valleys and the neighborhood of the Gamma valley. The first absorption peak of light polarized in the basal plane, e perpendicular to c, is associated with transitions from the lower level with symmetry Gamma(1) in the quantum Gamma well to two close-lying levels with symmetry Gamma(3). The absorption of light with polarization parallel to the hexagonal axis, e parallel to c, is weaker, and the peak is shifted toward higher energies. Because of this, an array of small GaN QDs can be used in IR photodetectors with the light incident on the front. A technology for obtaining arrays of small QDs with high density is proposed and developed.