Academic literature on the topic 'Atomic Al-doping'

In this study, CuO nanostructured films conjunction with metal doping have been deposited onto soda lime glass (SLG) substrate by method of spin coating at different doping concentration in solution (0%, 2% and 4%). X-ray diffraction (XRD) patterns for copper oxide films conjunction with Al doping demonstrated that the films have polycrystalline structure and have preferential growth in (-111) and (200) directions. Calculated dislocation density value of (-111) plane is changed between 3.7 x 1014 and 5.83 x 1014 m-2 and 83.7 x 1014 and 50.6 x 1014 m-2 for (200) owing to the expansion of structural parameters with Al dopant content in solution. In order to investigate surface morphology, we used an atomic force microscopy (AFM). The obtained results from AFM revealed that samples are comparatively smooth in the valley area while many crystals-like structures are seen in the hill area. In order to examine absorbance, energy band gap and transmittance value of Al doped CuO films, we used a UV-Vis measurements system in the range of 1100-300 nm at temperature of 273 K. The obtained samples have high absorption in the region of UV-Vis and have a high affinity for UV light. It can be said that the change in the absorption value is a result of the different crystal nature of the samples. Energy band gap value of Al:CuO thin films changed between 1.98 and 2.07 eV.

In the last three decades, Zinc oxide (ZnO) has been found to be one of the most resourceful materials having tremendous potential applications in manifolds covering a wide variety of areas. It is continuously explored in different forms and structures. ZnO-based layers have an established place in the industry that ranges from protecting degradable items to detecting toxic gases. A wide variety of ZnO-based advanced coatings and their surface treatments along with innovative functionalization technologies offer a multitude of options for making them useful in diverse industries. Multiple techniques ranging from exceedingly sophisticated ones like molecular beam epitaxy and atomic layer deposition to highly-cost effective ones like sol-gel spin coating and dip coating, etc. have been used for developing the ZnO based thin films. Doping suitable elements into ZnO matrix is the most promising strategy to alter its properties drastically. Out of numerous dopants, Aluminum (Al) offers some of the excellent and reproducible features in ZnO films which make Al doped ZnO (AZO) a reputable system in industries like thin film transistor manufacturing and solar cells. Specifically, its established and repeatable behavior in terms of transparency and conductivity becauseis finding huge applications as a transparent conducting oxide (TCO). Extensive research on AZO coatings derived from different methods day-b-day opens up a new gateway for interesting perspectives by optimizing surface nanostructures. Here a brief account of historical developments of ZnO to AZO films along with their applications in certain key areas like TCOs, solar cells, thin film transistors, flexible electronics and plasmonics, etc. is presented.

Since the discovery of soccer-ball-shaped C60 (Kroto et al., 1985), fullerenes have been added to the family of allotropes of carbon element. During the fullerene formation by arc-discharge of graphite electrodes, carbon nanotubes were simultaneously grown as a deposit on the electrode (Iijima, 1991). The carbon nanotubes consist of single or multiple graphene sheets rolled in the form of a seamless cylinder, with the diameter of the hollow core being almost 10 Å (similar to that of fullerenes) or even as small as 4 Å. For these new forms of nanometer-sized carbon, so-called nanocarbons, basically similar concepts as GICs have been applied from the aspects of structures, electronic properties, and functionalities that can be controlled by doping or intercalation process. That is, the bonding force between nanoballs or nanotubes is governed by weak van der Waals forces, so that foreign species such as atoms or molecules can be intercalated (or doped) in the van der Waals gaps, similar to graphite. So, from applications and the basic science of these new carbon families, intercalation as well as doping to these hosts has been studied intensively in the last ten years. There are three kinds of doping reactions of guest species into these host materials, which are reflected in their specific structure. Guest atoms can be introduced by substituting the carbon atoms of the hosts. This process is generally called “doping,” as there is a similarity with the doping process in semiconductors, where, in general, there is no long-range periodicity in the guest arrangement against the host crystal. Guests can locate in the hollow cores of fullerenes or carbon nanotubes as well as on their outer surfaces. GICs establish the super-lattice structure between the host of the graphite lattice and the inserted guest species, where the long-range periodicity along the c-axis as well as on the a-b plane is formed. According to the original meaning of “intercalation,” periodic doping to the host materials is defined as intercalation. So, the three kinds of doping are: (1) endohedral doping into the hollow cage; (2) substitutional doping by replacing the carbon atoms on the cages; and (3) exohedral doping where the dopants are sited in the gaps between the cage molecules of a fullerene crystal or between carbon nanotubes in the array of the bundle form.

Abstract Silicon-based MEMS devices are made from single-crystal silicon, LPCVD polysilicon films and other ceramic films (Bhushan, 1998). For high temperature applications, SiC films are being developed to replace polysilicon films. Tribology in the MEMS devices requiring relative motion is of importance. Atomic force/friction force microscopy (AFM/FFM) and nanoindentation techniques (Bhushan et al., 1995; Bhushan, 1995, 1998) have been used for tribological studies on micro- to nanoscale on materials of interest. These techniques have been used to study surface roughness, friction, scratching/wear, indentation and boundary lubrication of bulk and treated silicon, polysilicon films and SiC films (Bhushan, 1996a, b; Bhushan et al., 1994, 1997a, b, 1998; Koinkar and Bhushan, 1997; Li and Bhushan, 1998; Sundararajan and Bhushan, 1998; Zhao and Bhushan, 1998). Macroscale friction and wear tests have also been conducted using the ball-on-flat tribometer. (Bhushan and Venkatesan, 1993; Gupta et al., 1993, 1994a, b; Venkatesan and Bhushan, 1993, 1994). Measurements of microscale and macroscale friction forces show that friction values on both scales of all the silicon samples are about the same among different silicon materials and higher than that of SiC. The microscale values are lower than the macroscale values as there is less ploughing contribution in the microscale measurements. Surface roughness has an effect on friction. In microscale and macroscale tests, C+-implanted, oxidized and PECVD oxide-coated single-crystal silicon samples exhibit much larger scratching and wear resistance as compared to untreated samples. Polysilicon films and undoped single-crystal silicon show similar friction and wear characteristics. Doping of polysilicon film does not affect its tribological properties. Microscratching, microwear and nanoindentation, and macroscale friction and wear studies indicate that SiC films are superior when compared to the other materials currently used in MEMS devices. Higher hardness and fracture toughness of the SiC film is believed to be responsible for its superior mechanical integrity and lower friction. Chemically grafted self-assembled monolayers and chemically-bonded liquid lubricants show promising performance for boundary lubrication in MEMS devices.