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In this work, we have prepared Sn-doped zinc oxide (SZO) thin films in the range of Sn concentrations of 0–6 wt.% using the spin coating technique to integrate them as emitters in the SZO/p-GaAs photovoltaic structure. The films exhibited a hexagonal würtzite structure highly oriented along the c -axis of the lattice. The SZO film with 3 wt.% Sn showed less strain and stress of lattice. The mean grain size and surface roughness increased with the Sn rate. Additionally, the films demonstrated high optical transmittance and low reflectance in the visible range; also, the films recorded a slight decrease in the optical band gap and refractive index versus the Sn content. Photoluminescence spectra revealed a decrease in ZnO intrinsic defects with Sn rate. The electrical resistivity of the films is strongly dominated by the charge carrier mobility. The SZO film with 3 wt.% Sn recorded the minimal resistivity. Subsequently, numerical simulation showed that the electrical properties of the SZO emitter strongly limit the photoelectric performance of the SZO/p-GaAs structure. The conversion efficiency increased from 0.204% to 14.65% for a high mobility of 25 cm 2  V −1  s −1 and a carrier density of 5 × 10 19  cm −3 in the SZO emitter zone.

We have studied the structural, optical, electronic and electrical properties of pure and Mg doped ZnO nanosheets compared to bulk ZnO, using the Density Functional Theory (DFT) within the Full Potential Linearized Augmented Plane Wave (FP-LAPW) formalism. The calculated band structure, total and partial densities of states show that the ZnO nanosheet have a large band gap than the other found in the bulk ZnO, which increases with increasing concentration of Mg. The absorption coefficient and optical transmittance show a red-shift after doping ZnO, whereas, the reflectivity and electrical conductivity are reduced. These good optical properties of ZnO nanosheets make it promising in optoelectronic devices, especially in solar cell application.

In this study, zinc oxide nanowires are elaborated by the hydrothermal method using a microwave furnace, which varies power and deposition times. The growth of nanowires is done on a buffer layer deposited on glass substrates using the sol–gel method associated with spin-coating. The X-Ray Diffraction (XRD) spectrums indicate that the obtained nanowires are well oriented in (002) plane according to the hexagonal wurtzite phase. The density and length of these nanowires increase while their diameter decreases with the deposition time and the microwave power. For high powers and longer deposition times, the ZnO nanowires adopt a pyramidal shape due to the low concentration of OH − hydroxides in the deposition solution. The elaborated nanowires have an optical transmittance level in the visible region of about 90% with a red shift of the optical gap as the deposition time increases qualifying them for photovoltaic and other optoelectronic applications. A correlation between the diameter of the nanowires and their optical gap has been found which illustrates the narrow relationship between the structural, electronic, and optical aspects of these nanowires.

Currently the doped or undoped ZnO semiconductor is of great importance in the field of electronic and optoelectronic devices such as transparent conductors and optical windows of solar cells based on silicon. ZnO thin films are produced by several techniques such as sol-gel method which is a chemical technique usually dependent on solution conditions. However, the sol gel aging time is an important parameter, which can have a significant impact on the properties of thin films. In this work we studied the effect of aging times (0h, 24h, 48h, 72h, 1 week) of the precursor solution on the structural and optical properties of ZnO doped Al (3 at.%). Thin films prepared by spin coating on glass substrates were investigated. The X-ray diffraction (XRD) analysis shows that the ZnO doped Al (3 at.%) exhibit the hexagonal wurtzite structure with a preferential orientation along [002] direction. The shift of (002) peaks towards higher diffraction angles is observed with sol aging time and also, a variation of crystallite sizes and thickness of thin films are shown with increasing sol aging time. All films present an average optical transmittance around 90% in the visible range with some interference fringes indicating a relative smoothness of films. We note an increasing in transmittance level with sol aging time from 0h to 48h. We can conclude that the aging times of the precursor solution influences the structural and optical properties of studied thin films.

Physical properties of Gallium doped ZnO in wurtzite phase has been studied. We have used the Generalized Gradient Approximation (GGA) to determine the structural parameters of each concentration of Ga. The modified Becke-Johnson potential TB-mBJ has been used to calculate the partial and total density of states. The dielectric function, refractive index, optical reflectivity, absorption coefficient and transmittance spectra were predicted using the same potential. The calculated energies of bands structure has been used with the Boltzmann transport equation to calculate the electrical conductivity of Ga doped ZnO. We have observed that the donor concentration, optical band gap and electrical conductivity can be widely tunable with the doping levels of Ga. The results of pure and doped ZnO were in agreement with experimental and other theoretical studies. The obtained results confirm that Ga doped ZnO is a transparent conductor dedicated for applications in photovoltaic devices.

The growth of GaSb thin films by MBE on GaAs (001) is investigated experimentally, using TEM, and theoretically, using KMC simulations. The atomic scale mechanisms inherent to the growth are discussed and described in the KMC model in which the strain is introduced through an elastic energy term based on a valence force field approximation. We observe that the first two monolayers of the deposited films form strained three-dimensional clusters, but further deposition induces film relaxation and rough 3D growth with valley formation presenting (111) facets with unstable bottoms. We show that the roughening morphology and creation of grooves during growth are in agreement with experimental TEM observations.

A comparative study of wurtzite ZnO doped by rare earth elements (Tm, Yb, Ce) have been investigated using density functional theory (DFT) based on the full-potential linearized augmented plane wave orbital (FP-LAPW) method, as implemented in Wien2K code. The structural parameters were calculated by PBEsol functional and in good agreement with the experimental data. The electronic (density of states, band structure) and optical (absorption coefficient, reflectivity, refraction index) properties were determined by TB-mBJ potential. The rare earth element doped ZnO have a significant impact on the optoelectronic properties which are mainly arise due to the presence of 4f electrons. The results of electronic structure shows that the doping of Tm, Yb, Ce on pristine ZnO has increases the band gap and in qualitative agreement with the experimental results. In many cases the Fermi level has been shifted to the conduction band, revealing n-type characters. Electrical conductivity has been calculated using BoltzTrap code based on the semiclassical equation of Boltzmann. It has been observed that the conductivity has a direct relation with the temperature and carriers concentration. Our results provide the basis for future research in Tm, Yb, Ce doped ZnO compounds used as integrated optoelectronic devices and solar cells.