Quantum magnetoconductivity characterization of interface disorder in indium-tin-oxide films on fused silica

Disorder arising from random locations of charged donors and acceptors introduces localization and diffusive motion that can lead to constructive electron interference and positive magnetoconductivity. At very low temperatures, 3D theory predicts that the magnetoconductivity is independent of temperature or material properties, as verified for many combinations of thin-films and substrates. Here, we find that this prediction is apparently violated if the film thickness d is less than about 300 nm. To investigate the origin of this apparent violation, the magnetoconductivity was measured at temperatures T = 15 – 150 K in ten, Sn-doped In2O3 films with d = 13 – 292 nm, grown by pulsed laser deposition on fused silica. We observe a very strong thickness dependence which we explain by introducing a theory that postulates a second source of disorder, namely, non-uniform interface-induced defects whose number decreases exponentially with the interface distance. This theory obeys the 3D limit for the thickest samples and yields a natural figure of merit for interface disorder. It can be applied to any degenerate semiconductor film on any semi-insulating substrate.

Optical study of electron and acoustic phonon confinement in ultrathin-body germanium-on-insulator nanolayers

Ge-on-insulator (GeOI) acoustic phonon frequencies and E1 electron band gap vs. GeOI thickness (T) show agreement with confinement theories at T > 5 nm and disagree at T < 5 nm. Al2O3 coating improves agreement at T < 5 nm due to interface disorder reduction.

Interface disorder in large single- and multi-shell upconverting nanocrystals

Single- and multi-shell upconverting nanocrystals, with their increasing numbers of applications, are characterized by core–shell and shell–shell interfaces, which are not yet fully understood. In this contribution, the magnitude of interface disorder in large single- and multi-shell nanocrystals is investigated.

Asymmetric double quantum wells with smoothed interfaces

We have derived and analyzed the wavefunctions and energy states for an asymmetric double quantum well (ADQW), broadened due to interdiffusion or other static interface disorder effects, within a known discreet variable representative approach for solving the one-dimensional Schrodinger equation. The main advantage of this approach is that it yields the energy eigenvalues, and the eigenvectors, in semiconductor nanostructures of different shapes as well as the strengths of the optical transitions between them. The behaviour of ADQW states for the different mutual widths of coupled wells, for the different degree of broadening, and under increasing external electric field is investigated. We have found that interface broadening effects change and shift energy levels, not monotonously, but the resonant conditions near an energy of sub-band coupling regions do not strongly distort. Also, it is shown that an external electric field may help to achieve resonant conditions for inter-sub-band inverse population by intrawell emission of LO-phonons in diffuse ADQW.