In this paper, the analysis, synthesis and characterization of thin films of a-Si:H deposited by PECVD were carried out. Three types of films were deposited: In the first series (00 process), an intrinsic a-Si:H film was doped. In the second series (A1–A5 process), n-type samples were doped, and to carry this out, a gas mixture of silane (SiH4), dihydrogen (H2) and phosphine (PH3) was used. In the third series (B1–B5 process), p-type samples were doped using a mixture of silane (SiH4), dihydrogen (H2) and diborane (B2H6). The films’ surface morphology was characterized by atomic force microscopy (AFM), while the analysis of the films was performed by scanning electron microscopy (SEM), and UV–visible ellipsometry was used to obtain the optical band gap and film thickness. According to the results of the present study, it can be concluded that the best conditions can be obtained when the flow of dopant gases (phosphine or diborane) increases, as seen in the conductivity graphs, where the films with the highest flow of dopant gas reached the highest conductivities compared to the minimum required for materials made of a-Si:H silicon for high-quality solar cells. It can be concluded from the results that the magnitude of the conductivity, which increased by several orders, represents an important result, since we could improve the efficiency of solar cells based on a-Si:H.

Simulations on mobility influence in optoelectronics parameters from an InGaN/GaN blue LED using the Nextnano++ software arepresented in this paper. These simulations were performed by changing the hole and electron mobility value for the material compounds according to experimental, theoretical, and doping-concentration data already reported in the literature. The power law mobility is used for the current calculation in the quantum drift-diffusion model. The results indicate the lower hole and electron leakage currents correspond to the lowest mobility values for the InGaN alloy, the greatest amount of recombination occurs in the extreme wells within the active layer of the LED and the stable emission is at 3.6 V with peak wavelength λ^LED=456.7 nm and full width at half maximum FWHM~11.1 nm for the three mobilities. Although experimental and theoretical mobility values reach higher carrier density and recombination, the photon emission is broader and unstable. Additionally, the doping-concentration mobility results in lower wavelength shifts and narrows FWHM, making it more stable. The highest quantum efficiency achieved by doping-concentration mobility is only in the breakdown voltage (ηdop−max=60.43%), which is the IQE value comparable to similar LEDs and is more useful for these kinds of semiconductor devices.

The amorphous silicon (a-Si) is a material which has had a great acceptance in the microelectronic industry field due to its low cost in comparison with the one of crystalline silicon (c-Si). This material has a random network in its atomic structure, since its atoms are not located to either a specific angles or distance. In 1969, Chittik et al. [1] added hydrogen to the amorphous silicon finding a beneficial effect, since it saturated the defects of the network. This finding was key for the development of the amorphous semiconductors. Thus, W. Spear and P. LeComber [2] showed that silicon has semiconducting properties when together with a dopant gas such as phosphine and diborane. The hydrogenated amorphous silicon (a-Si:H) appears as a promising material in the photovoltaic industry due to its high absorption coefficient and low manufacturing cost [3,4]. Therefore, the optical and electrical properties of a-Si:H films, such as transmittance, absorption coefficient, conductivity, activation energy and thickness are very important. These properties can be optimized by the deposition process parameters, such as power, frequency mode, argon flow rate, temperature and principally the pressure deposition [5-7]. This parameter has influence in the transmittance, absorption coefficient and conductivity because is proportional to deposition rate and stress (compressive). In this work, the a-Si:H films were fabricated by the Plasma Enhance Chemical Vapor Deposition (PECVD) process at low frequency with a substrate temperature of 300 o C, varying the flow of hydrogen and dopant gases. In this way, implementing the PECVD technique, thin films have been doped with PH 3 (n-type) and with B 2 H 6 (p-type). The procedure was repeated with different values of flow of PH 3 and H 2 for the n-type films and B 2 H 6 and H 2 for ptype ones. To investigate the effects of pressure on the deposition in the a-Si:H films, all experimental parameters for various samples were kept constant except for the deposition pressure. The values of RF power, substrate temperature, and deposition time were 10 W/cm 2 , 300°C, and 30 minutes, respectively. On the other hand, the deposition pressure was varied to from 725 to 2500 mTorr in order to investigate the effects of this parameter on the films structure. In each experiment, the films were deposited both on glass as well as silicon substrates. The characterization of samples and the evaluation of the process were done by the measurements of the absorption coefficients, the conductivities, the activation energies and of the thickness of the films. In the Figures 1(a) and (b), we show the AFM images for the n-type and p-type, respectively, with different deposition pressure values. For both cases, for low deposition pressure values the nanoclusters do not appear, however these appear when the deposition pressure increase, this study reports the analysis of Si nanoparticles of approximately 1.5 nm in size, see Figure 1(f). A graph of absorption coefficient of a-Si:H layer as a function of wavelengt...

The hydrogenated amorphous silicon (a-Si:H) appears as a promising material in the photovoltaic industry due to its high absorption coefficient and low manufacturing cost [1-2]. However, light management and control are forms crucial components in high efficiency solar cells. For example, the textured surfaces at the contacts of the solar cells can increase light trapping, such it is a yield important improvement of the overall efficiency. A new concept of trapping light is the use of "plasmonics", the electronic response of free electrons to light interacting with metal nanostructures [3]. One of the most important experimental investigations of plasmonic enhancement for photovoltaic involved the scattering of silver nanoparticles in an organic solar cell [4].

In this study, the impact of pH on the production of ZnO nanostructured thin films using chemical bath deposition was investigated for the purpose of enhancing the efficiency of solar cells. The ZnO films were directly deposited onto glass substrates at various pH levels during the synthesis process. The results indicate that the crystallinity and overall quality of the material were not affected by the pH solution, as observed through X-ray diffraction patterns. However, scanning electron microscopy revealed that surface morphology improved with increasing pH values, leading to changes in the size of the nanoflowers between pH 9 and 11 values. Furthermore, the ZnO nanostructured thin films synthesized at pH levels of 9, 10, and 11 were utilized in the fabrication of dye-sensitized solar cells. The ZnO films synthesized at pH 11 exhibited superior characteristics in short-circuit current density and open-circuit photo-voltage compared with those produced at lower pH values.