Naumenko M. Electronic properties of nanostructures based on β-Ga2O3

Theoretical calculations were performed using the electron density functional, the pseudopotential from first principles, and our own software code for evaluating the electronic properties of various nanostructures based on β-Ga2O3. The controlling effects of the thickness, the type of free surface, and the mechanical effect of compression on the conductive properties of β-Ga2O3 ultrathin films were determined. It was established that the film with the (010) surface 0.304 nm thick, which was interpreted as a 2D object, in its initial (uncompressed) state has a band gap almost five times larger than that of a massive β-Ga2O3 crystal. A film with a non-flat surface (100) 1.29 nm thick, when compressed to 30 %, has a band gap equal to zero. During the compression of ultrathin films, orientational defects of chemical bonds are formed, which are manifested in a sharp and non-monotonic change in the widths of the electronic band gaps. The sensory sensitivity of β-Ga2O3 nanoparticles of different shapes (spherical and prismatic) to CO, NH3, O3 gas molecules near or near Ga or O atoms was studied. It was established that nanoparticles of both shapes can serve as effective resistive detectors of CO and NH3 molecules. A brighter reaction to CO molecules is recorded in spherical particles, and a brighter reaction to the NH3 molecules is recorded in a prism-like particle. At the same time, the active area of nanoparticles as detectors was localized near Ga atoms. Only spherical nanoparticles effectively reacted to O3 molecules, increasing their conductivity. Synergistic properties of nanowire arrays based on β-Ga2O3 were established by determining the degree of influence of wires on each other depending on the geometric parameters of their mutual location in the array and electronic characteristics of the array of wires as a whole. Arrays of β-Ga2O3 wires of cylindrical shape and larger diameter reveal more controlled and physically justified synergistic electronic characteristics than arrays of cylindrical wires of smaller diameter and prismatic shape. The effectiveness of doping p-type nanoobjects based on β-Ga2O3 with various metals and nonmetals was evaluated. Promising p-type impurities were indicated: atoms of divalent metals – Mg, Ca, Zn, replacing gallium atoms and non-metal atoms N, replacing differently positioned oxygen atoms.