Semiconductor thin films

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The scanning electron microscope as a flexible tool for investigating the properties of UV-emitting nitride semiconductor thin films

The scanning electron microscope as a flexible tool for investigating the properties of UV-emitting nitride semiconductor thin films

Techniques have also been developed to identify dislocation types [11,24,40]. Nitride semiconductors contain three types of TDs, namely screw-, edge-, and mixed-type dislocations. To identify the TD type, it is possible to apply the “ invisibility criteria” used in transmission electron microscopy (TEM) [11]. In simple terms, dislocations are invisible in an ECCI or TEM micrograph if they do not distort the plane which diffracts the incident electron beam. The invisibility criteria are satisfied for screw dislocations where g · b 0 and for edge and mixed dis- locations where g · b 0 and g · b × u 0 . g is the vector normal of the diffracting plane, b is the Burgers vector of the TD, and u is its line direction. For ECCI, to determine g an electron channeling pattern is usually acquired [11]. However, a further factor which needs to be taken into account when attempting to apply the invisibility criteria to ECCI images (and plan view TEM images), is the effect of surface relaxation on the observed defect contrast. The variation in strain due to surface relaxation around a defect can dominate the observed defect contrast [11]. For nitride semiconductor thin films, sur- face relaxation has a major impact on the observed TD contrast, so additional strategies have been developed to identify the TDs. As discussed above, in an ECCI micrograph TDs appear as spots exhibiting B-W contrast. If two (or more) ECCI micro- graphs of the same area are acquired at different diffraction conditions, the direction of the B-W contrast exhibited for each TD may be compared. If the B-W contrast direction for a given TD remains the same or is reversed, the TD is an edge dislocation. If the B-W contrast changes its direction by other than 0° or 180°, then the dislocation contains a screw component, so it is a screw or mixed TD. One advantage of this latter strategy is that it can be applied without a precise knowledge of g .
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A Theoretical Study on Van Der Pauw Measurement Values of Inhomogeneous Compound Semiconductor Thin Films

A Theoretical Study on Van Der Pauw Measurement Values of Inhomogeneous Compound Semiconductor Thin Films

The effect of intermixing of heterogeneous regions in compound semiconductor thin films on the electrical properties obtained by the van der Pauw method were investigated by simulation using the FEM. The calcu- lated electrical properties varied predictably according to the electrical properties of the heterogeneous regions when the regions were dispersed over the entire sample area. The deviations of electrical properties of inhomo- geneous samples from those of the homogeneous base materials were not very large when the total ratio of the heterogeneous region was lower than approximately 10% in such cases. On the other hand, the calculated mobility tended to increase unexpectedly by the intermixing of heterogeneous regions when the regions were concen- trated locally in the samples, even though the mobilities of the intermixed heterogeneous regions were lower than that of the base material. Thus, the electrical properties of inhomogeneous compound semiconductor thin films obtained by the van der Pauw method are dependent
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Epitaxial Growth of Room Temperature Ferrimagnetic Semiconductor Thin Films Based on Fe3O4 Fe2TiO4 Solid Solution

Epitaxial Growth of Room Temperature Ferrimagnetic Semiconductor Thin Films Based on Fe3O4 Fe2TiO4 Solid Solution

deposition technique. A single phase of (111)-oriented solid solution can be obtained by adjusting the oxygen partial pressure and substrate temperature. The epitaxial solid solution thin film exhibits ferrimagnetism with Curie temperature above room temperature and is a semiconductor with n-type conduction carriers. Anomalous Hall effect is observed at room temperature for the solid solution thin films, implying the presence of spin-polarized charge carriers. [doi:10.2320/matertrans.MC200804]

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Detailed Analysis of Five Aspects Addressed to Minimize Costs and Waste in the Chemical Bath Deposition of CdS Films Using the CdB–AC6H5O7–AOH–(NH2)2CS System

Detailed Analysis of Five Aspects Addressed to Minimize Costs and Waste in the Chemical Bath Deposition of CdS Films Using the CdB–AC6H5O7–AOH–(NH2)2CS System

A few authors have addressed some points related to these issues. For the case of a citrate–ammonia-con- taining system, the group of Nair and Nair conducted a mathematical model which can qualitatively account for most of the features of the experimental growth curves of the chemically deposited semiconductor thin films [84], a model that was used to study the thin film yield as a function of the separation among substrates in batch production, and they established that there is an optimum separation at which, for a given bath composition and temperature, about 90% of the maximum possible proc- ess yield is achieved [125]; based on this, they reported the achieving of a thin film yield of almost 100% for CdS with final d of about 50 nm by using very small substrate separation—0.1 mm—[133]. With the aim to improve yield and reduce waste in other ammo- nia-containing systems, Hariskos et al. synthesized CdS thin films by using fresh CdCl 2 solutions and reusing the
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Volume 9 | Issue 3 - 2019

Volume 9 | Issue 3 - 2019

The crystallographic structure of NiO:Al films were characterized by XRD, which is presented in Fig (1). The XRD analysis indicates that all samples of the films NiO:Al deposited of undoped and doping (x= 0.5, 1, 1.5 and 2) wt% were polycrystalline and retain the NiO peaks of the film corresponding to 111, 200, and 222 reflections positions. The film deposited with x = 1.5% was disappeared polycrystalline

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Manufacture, Applications, and Opportunities of Thin Film Palladium-Silver (PdAg) Alloys: A Review

Manufacture, Applications, and Opportunities of Thin Film Palladium-Silver (PdAg) Alloys: A Review

In this review we have explored the manufacture and applications of the industrially important palladium silver alloy films. While the use of PdAg membranes for hydrogen purification has been known for many years and still represents the current research paradigm, further exploration of the capabilities of these materials in this and related applications have been undertaken. The most recent developments in the use of PdAg films are in highly selective sensing applications, primarily for the detection of H 2 , but also other low molecular weight species such as CH 4 . Electrocatalytic applications
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Composition and crystalline properties of TiNi thin films prepared by pulsed laser deposition under vacuum and in ambient Ar gas

Composition and crystalline properties of TiNi thin films prepared by pulsed laser deposition under vacuum and in ambient Ar gas

The enhanced thickness in Ar atmosphere at the entire target-substrate distance range than that under vacuum is attributed to the collisions between the ablated Ti/Ni species and the Ar ambient molecules. Because of the collisions, more Ti and Ni species can reach a substrate in Ar atmosphere as compared to those under vacuum deposition over the entire target- substrate distance range. Moreover, the greatly enhanced thicknesses of TiNi thin films at distances of 25 mm and 30 mm in the case of the 200-mTorr Ar atmosphere are caused by the shock front consisting of high-density ablated Ti and Ni species. In this paper, a 200-mTorr Ar pressure is high enough to form the shock front, and distances of 25 mm and 30 mm may be a region of the shock front. Also, the result of Figure 2 could be explained by the shock front. A number of collisions between the ablated species(Ti/Ni) and Ar gas molecules are increased at the shock front. Therefore, the ablated species(Ti/Ni) move at a constant velocity, despite of the different masses of Ti and Ni. Because of this, the compositions of the thin films are very close to the target ’ s composition when the substrate is placed at the shock front. Compositions of the thin films depos- ited using conventional sputtering method were greatly different from the target ’ s composition, necessitating the need of suitable methods to control the composition. The result presented here implies that TiNi thin films which are close to the target’s composition using PLD at the shock front in 200-mTorr Ar atmosphere are obtained easily.
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Structural templating in a nonplanar phthalocyanine using single crystal copper iodide

Structural templating in a nonplanar phthalocyanine using single crystal copper iodide

Preparation of CuI single crystals was undertaken to avoid the limited grain size and random in-plane orientation in pre- viously presented CuI thin fi lms. The crystals exhibited hex- agonal or triangular habit from slow growth in saturated ace- tonitrile solution ( Figure 1 a). This is indicative of expression of threefold or sixfold planar symmetry in the top faces of these crystals suggestive of (111) orientation. For surface analysis by low energy electron diffraction (LEED), crystals were mounted on Ta sample plates and loaded into UHV where diffraction patterns were collected without any surface preparation. LEED showed a hexagonal arrangement of spots consistent with a 1 × 1 (111) pattern with no additional spots at lower energies (Figure 1 b). Additionally, X-ray diffraction (XRD) patterns were recorded (in ambient conditions) after careful alignment to the surface normal of the crystal and only {111} refl ections were observed (Figure 1 c). Atomic force microscopy (AFM) images (collected in ambient air) showed that the top faces were fl at with 60 ° rotational symmetry in their step edge arrangement ( Figure 2 a, b). The combination of these experimental observa- tions established that the crystals are of high quality and pos- sess large exposed (111) top surfaces.
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													Structural and electrical properties of   sns thin films via   chemical bath deposition technique

1. Structural and electrical properties of sns thin films via chemical bath deposition technique

(TA)(0.1M,0.3&0.5M) of experimental design was added in to the same beaker and the mixture solutions were again stirred. Among this experiment ammonia was added to change the PH in to certain values (PH 9.20, 9.19&8.76) using PH meter. Later the solution poured into another beaker containing clean glass substrate, clamped vertically. The deposition is made at room temperature, the bath colour leaving a clear red to a permanently chocolate brown. SnS films nucleated on to submerged surfaces, including beaker walls in about 24h for one deposition run. At the end of each deposition run, the layer is rinsed in bid stilled water. The sample was preserved in the desiccators for 2-3days and kept for further analysis. In order to investigate the crystallographic properties of the tin sulphide thin films we carried out the x-ray diffraction analysis using CINEL XRG 300 X-ray diffractometer with CuKα radiation. The surface morphology was observed by a scanning electron microscopy (JEOL, JSM-6400), at 15 kV with a 25.00KX magnification.
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Substrate Temperature Effect on Optical property of ZnO Thin Films

Substrate Temperature Effect on Optical property of ZnO Thin Films

The X-ray diffraction pattern of undoped ZnO thin films is presented in Fig. 5. The thin film was deposited at a substrate temperature of 350 °C, as it can be seen the diffraction peaks were observed at = 31.8°, 34.5°, 36.4°, 47.5° and 56.55° which are related to the following plans (100), (002), (101), (102) and (112) respectively. The obtained XRD spectra matched well with the space group P63mc (186) (No. 36- 1451) of the wurtzite ZnO structure [23]. Moreover, single significant (100) diffraction peak, with height intensity, was observed for the ZnO film which indicate that the ZnO film have preferential a-axis orientation perpendicular to the crystallographic plans (100). These results can be explained as it was expressed in the literatures [20, 23, 24, 27].
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Effect of Different Current Density on Structural and Mechanical Properties of Fe-Ni-Co Alloy Thin Films

Effect of Different Current Density on Structural and Mechanical Properties of Fe-Ni-Co Alloy Thin Films

and morphological, structural, and mechanical characterization were analysed. The SEM micrographs of the electrodeposited films w i t h d i f f e r e n t c u r r e n t d e n s i t y have n o micro- cracks and also the films have uniform surface morphology. The predominant peaks in X-ray diffraction pattern reveal t h e crystalline n a t u r e of the film and structure belonging to FCC. The hardness changes of thin films were analysed by VHT. The electroplated Fe-Ni-Co thin films were strongly adherent to the substrate. The VHN result of Fe-Ni-Co thin films shows that the Fe-Ni-Co thin films coated at high current density have highest hardness value.
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Fabrication and characterization of antibacterial surfaces derived from geranium essential oil using PECVD

Fabrication and characterization of antibacterial surfaces derived from geranium essential oil using PECVD

Many reports showed that gram-positive bacteria appear to be more resistant against ZnO NPs [58, 59]. This linked to the specific thick and negatively charged peptidoglycan layer in the bacterial cell wall that can resist ZnO penetration. In contrast, other findings have found that gram-negative bacteria are more resistant to NPs activities [60-62]. In addition, more experiments showed that ZnO had almost similar effect on both bacterial strains [63]. It can be understood that contradictory results in which bacteria are more resistant. Indeed, ZnO NPs are currently manufactured with different dimensions, morphologies, concentrations, modifications, surface defects, surface charges, crystallographic orientation etc. The antibacterial mechanisms vary based on the physicochemical properties of nanoparticles and their microenvironment conditions. For example, in different media, the dissolving profile of Zn may varies according to the medium components, and accordingly have potential influence upon the follow-on toxicity mechanism[64]. However, in our experimental conditions, attached bacterial cells on the Zn/Ge composites did not expose to only ZnO nanoparticles, but rather they were affected by both released-ZnO and geranium polymer surfaces at the same time. Geranium polymers contains chemical groups (e.g. hydroxyl and carboxyl), which proved in a previous study to reveal moderate antibacterial and anti-biofouling activities. The inhibitory effects of Zn/Ge composite films were observed to be very similar on S. aureus and E. coli. Furthermore, we expect that interactions between the geranium oil vapors (contain alcohols) and ZnO NPs occurred during composites fabrication. Here, more desired functional groups are presented on ZnO surface, which is modify. Surface modifications of the ZnO NPs in oxidizing environments had been demonstrated to cause an impotent change in the antibacterial activity[65], which can be utilized in biomaterials. For example, Galindo et al. modified the surface of ZnO NPs by chemical components including di-functional alcohol, where these metallic particles can be used in antimicrobial medical devices [66].
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Structural and Optical Properties of Hydrothermally Grown Zns Thin Films

Structural and Optical Properties of Hydrothermally Grown Zns Thin Films

ABSTRACT: ZnS thin films were prepared using chemical bath deposition method and their optical and structural properties were studied. The ZnS thin films were grown on well cleaned glass substrates by hydro thermal method from aqueous solution of Zinc Sulphate and Thiourea at different growth temperatures. The properties of ZnS thin films and their growth mechanisms were studied using x-ray diffraction, SEM, EDAX, UV-Visible spectroscopy and photoluminescence measurements. Effect of growth temperature on structural and optical properties was reported.
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Characterization of cdxse1-xs/pbs thin films deposited by chemical bath deposition for p-n junction solar cell application

Characterization of cdxse1-xs/pbs thin films deposited by chemical bath deposition for p-n junction solar cell application

nanotechnology, it has been proven that cheap optoelectronic devices can be designed and fabricated for domestic and commercial electrical production (Piok et al., 2001). Nault (2005) found that heating from solar energy requires a P-N junction. The best alternative for oil, coal and gas as sources of energy is the solar cell. Armin (2009) reported that technology on thin film can be used to produce economically cheap optoelectronic devices that can arrest domestic electrical production. Solar energy is easily maintained and easily installable as well as being reliable. Siu and Kwok (1978) concluded that there was a need for the study of materials with good photoelectrical properties and more so the ones in the IR, VIS and UV regions of the spectrum. Good solar cells are the ones which are capable of absorbing photons from the sun and then converting that energy into electrical energy. The solar cell generally consists of two layers namely n-type layer and a p-type layer as illustrated in figure 1.1
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Nanoindentation of GaSe thin films

Nanoindentation of GaSe thin films

Figure 3a shows the typical nanoindentation load–dis- placement curve obtained for hexagonal GaSe films. The total penetration depth into the GaSe thin film was ap- proximately 80 nm with a peak load of approximately 0.23 mN, which is well within the nanoindentation cri- terion suggested by Li et al. [14], which states that the nanoindentation depth should never exceed 30 % of the films’ thickness or the size of nanostructures under test. The results displayed in Figure 3, thus, should reflect primarily the intrinsic properties of the present GaSe thin films. It is evident from Figure 3a that there are sev- eral pop-in events occurring along the loading segment of the load–displacement curve with the threshold load- ing of the first pop-in being around 0.1 mN. The plastic deformation behavior observed here is consistent with those reported for InSe and GaSe single crystals by Mosca et al. [15], albeit that in single crystal cases, the threshold of pop-in event occurred at slightly higher loadings (approximately 0.3 mN). Moreover, we note that the threshold loading of the present GaSe films is much lower than that of other hexagonal III-V semicon- ductors, such as AlN films deposited on c -plane sapphire substrates where the first pop-in occurred at approxi- mately 0.2 mN [16]. As pointed out by Mosca et al. [15], the plastic deformation of the layer-structured InSe and GaSe may involve breaking of In-In (or Ga-Ga) bonds, activation of dislocation slip, twinning, and bending mechanisms. On the other hand, as can be seen in both Figures 1a and 3a, the deformation between pop-ins is predominantly elastic even with a load up to 20 mN, suggesting that the slip process should play a prominent role in the deformation mechanisms of this layered ma- terial. Furthermore, since the pop-ins are generally closely related to the sudden collective activities of dislo- cations (such as dislocation generation or movement bursts), it is suggestive that during the course of plastic flow, preferential collective slips might be occurring by activating the pre-existing dislocations during thin film
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Indium Doped Zinc Oxide Thin Films: Effect on Structural, Optical and Electrical Characteristics

Indium Doped Zinc Oxide Thin Films: Effect on Structural, Optical and Electrical Characteristics

Figure 1 shows the SEM micrograph of both undoped and doped IZO films with 11.0kx magnification. Undoped films have smooth, closely packed grains which are uniformly distributed. When Indium (1%) was incorporated, the morphology changes to well defined nano fibers forming chain throughout the surface .The average width of the nano fibre was measured as 440nm. As the concentration of the dopant increases the surface becomes broken chain like nano structure. When the In concentration reaches 5% the morphology modified to spherical shaped particles spread throughout the surface.
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High capacitance thin films

High capacitance thin films

A high capacitance thin film structure was produced within the research group Interfaces and Correlated Electron systems of the University of Twente. Here fore strontium titanate was used as a dielectric material. The capacity per area (C/A) of this structure was measured in two ways and found to be for the quasistatic measurement C/A= 4.70 ± 0.03 µF/cm 2 and for the measurement at a frequency of 1kHz C/A= 3.85 ± 0.08 µF/cm 2 . In order to increase this values strontium doped barium titanate was synthesized in two different stoichiometries (Ba 0.5 Sr 0.5 TiO 3 and Ba 0.67 Sr 0.33 TiO 3 ) by the solid state synthesis method below 1200 ℃ . To be able to produce a stable target for the use in a laser ablation device, polyvinyl alcohol was added to the powders before pressing pellets at 20 and 25 ton respectively. After the second sinthering the Ba 0.67 Sr 0.33 TiO 3 pellet was cracked and so only growth conditions of the Ba 0.5 Sr 0.5 TiO 3 target were determined. It was found that by the use of a KrF excimer laser with a wavelength of 248nm and a pulse width of 30ns, an energy flux of 1.5 J/cm 2 was suitable in an 0.13 mbar O
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DEVELOPMENT OF PVDF THIN FILMS

DEVELOPMENT OF PVDF THIN FILMS

2.2.1 Substrate Preparation: The glass substrates were initially cleaned in Chromic Acid to remove the impurities from its surface, then the substrates are taken into a bowl containing Acetone & the bowl is placed in Ultrasonicator for a period of 10 min. Later the substrates are rinsed in De-ionized water to remove the remaining impurities & then the substrates are dried in hot air oven for removing the water contents [11-14]. 2.2.2 Thin film fabrication: PVDF Granules (Sigma-Aldrich co.) are used to fabricate thin films. Polar solvent N, N-Dimethyl formamide (DMF) (Mayora Scientific Co) was used to dissolve the PVDF. A solution of varying wt % of PVDF i.e., 10 %, 15 % and 20 % PVDF in DMF was prepared by mixing the different wt % PVDF Granules in N, N-DMF solvent and heated at 60°C with continuous stirring in a magnetic stirrer to completely dissolve all of the Granules in the solvent. The solution was then suitable for spin coating, Stretched PVDF film was prepared by spin coating the completely dissolved PVDF at 1000, 2000 and 3000 rpm for 10, 20, and 30 seconds on the glass substrates. Finally spin coated films were annealed using high temperature furnace. In order to study the effect of annealing treatment the samples were annealed at different temperatures of at 30°C, 40°C and 50°C for 1 hour to evaporate the solution and thereby curing the film. Annealing temperature higher than 70°C reduces the β- phase content in the film hence temperature was kept below it [15-19].
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Cadmium chalcogenide thin films

Cadmium chalcogenide thin films

Cadmium chalcogenide thin films have been prepared by many deposition methods. The main benefit of cadmium chalcogenide materials is produce high power conversion efficiency solar cells compared with other chalcogenide thin films. Unfortunately, cadmium is highly toxicity and non-eco-friendly substance. Therefore, researchers must work harder in order to seek the less toxic materials to replace cadmium.

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Macroporous WO3 Thin Films

Macroporous WO3 Thin Films

Photooxidation of Water Using Nanocrystalline WO3 Under Visible Light. International 258[r]

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