Small size GaN nanorods (GaN NRs) show new features of the photoluminescence (PL) associated with the
enhanced surface effects and the strong electron-phonon coupling. A dominant emission is observed at
3.43 eV; a lower energy with respect to the commonly reported D0XA peak for thicker NRs. The phonon
replicas of the silent B1l acoustic phonon mode are well represented in the PL spectra at temperatures up to
150 K inferring the enhanced Fröhlich electron-phonon coupling. The B1l phonon mode was previously
detected for the grown GaN NRs by resonant Raman scattering under resonance excitation. The enhanced
electron-phonon coupling through Fröhlich interaction is proven by the calculated Huang-Rhys factor. The
low-energy dominant peak intensity is around six times the D0XA peak intensity indicating that the majority
of excitons occupy the surface shell of GaN NRs. This study provides new insights on small-size GaN NRs
that greatly influence their physical properties for applications in optoelectronics, UV and blue lasers, and
high-temperature/high-power electronic devices
 

The research on binary chalcogenides as photovoltaic materials offers a great opportunity to lower the
manufacturing costs of solar cell devices. Thus, we choose to research tin sulfide (SnS) materials as a p-type layer in the SnS/Si heterojunction. Our research reports basic characterizations related to the annealing effect on theSnS films. The effect of substrate type was considered, where SnS films were deposited on glass and Si substrates. The Orthorhombic SnS phase is the main crystal structure of the as prepared polycrystalline SnS films. After thermal treatment, the deposited films on glass substrates maintained the same preferred orientation while  deposition on Si changed the preferred orientation to the Sn2S3 phase. The intensity of observed reflections in XRD charts decreased with increasing temperature of annealing (Ta) and the treated SnS film at Ta = 673 K showed an absence of ordered structure. The indirect transition showed the best linear fit for all investigated SnS films. The reported band gap energy (Eg) values increased after annealing from 1.29 to 1.50 eV. The thermal induced electrical behavior for SnS films showed the presence of deep impurity levels. Further, we conclude from the calculated values of σoІ that localized states-driven conduction is more reasonable in the high-temperature region. Besides, the SnS films exhibited dc conductivity in the range of 3 × 10-3–6 × 10-6 (Ω.cm)-1. Moreover, we reported the photovoltaic aspects of developed Al/n-Si/p-SnS/In solar cell devices. Data from J-V measurements indicated clear dependence on the SnS layer physical characteristics.
 

In this paper, we introduce three versions of fractional-order chaotic (or hyperchaotic)
complex Duffing-van der Pol models. The dynamics of these models including their fixed
points and their stability are investigated. Using the predictor-corrector method and Lyapunov
exponents we calculate numerically the intervals of their parameters at which chaotic,
hyperchaotic solutions and solutions that approach fixed points to exist. These
models appear in several applications in physics and engineering, e.g., viscoelastic beam
and electronic circuits. The electronic circuits of these models with different fractionalorder
are proposed. We determine the approximate transfer functions for novel values of
fractional-order and find the equivalent tree shape model (TSM). This TSM is used to
build circuits simulations of our models. A good agreement is found between both numerical
and simulations results. Other circuits diagrams can be similarly designed for other
fractional-order models.
 

The combination synchronization (CS) and combination-combination synchronization (CCS) for
chaotic and hyperchaotic dynamical systems with the same dimensions are introduced and studied in
the literature. In this paper, we introduce the definition of CS and CCS for those systems with different
dimensions.Westate two schemes to achieve these kinds of synchronization based on the active
control technique. Two theorems are stated and proved to provide us with analytical expressions for
the control functions.Westate four hyperchaotic dynamical systems with different dimensions which
are used as examples to achieve CS and CCS. These examples are hyperchaotic detuned laser, Lorenz,
van der Pol and dynamos systems. These systems appeared in many important applications in applied
science, e.g., a ring laser system of two-level atoms, vacuum tube circuit and two coupled dynamos
system. The validity of the analytical control functions are tested numerically and good agreement is
found between them. The numerical solutions ofODEsystems are calculated by using the method of
Runge-Kutta of order 4. Other systems can be similarly studied