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Defect characterization of MBE grown ZnSe/GaAs and ZnSe/Ge heterostructures by cross-sectional and planar transmission electron microscopy
Published in A G Cullis, P D Augustus, Microscopy of Semiconducting Materials, 1987, 2021
S B Sant, J Kleiman, M Melech, R M Park, G C Weatherly, R W Smith, K Rajan
ZnSe, with a direct band gap of 2.7eV at room temperature, has potential application as a material for the fabrication of blue light emitting devices. The quality of the material in terms of the structural defects present is important in order to fabricate useful devices. Since bulk-grown ZnSe crystals are of very poor quality, the main efforts to grow high quality material are concentrated in epitaxial growth. Over the last decade two techniques have emerged with promising results, namely, molecular beam epitaxy (MBE), and organo-metallic chemical vapour deposition (MOCVD). ZnSe thin films of high quality have been grown by both techniques on GaAs (Yao et al 1981, Stutius 1982, Park et al 1985) and Ge (Werthen et al 1983, Park and Mar 1986). GaAs and Ge were chosen as substrates because of their close lattice match to ZnSe (0.25% and 0.17% respectively) and promising heterojunction characteristics.
Introduction to Silicon Wafer Processing
Published in Kumar Shubham, Ankaj Gupta, Integrated Circuit Fabrication, 2021
Line Defects: Line defects or dislocations, are lines along which whole rows or columns of atoms in a solid crystal are arranged anomalously. The resulting irregularity in spacing is most severe along a line called the line of dislocation as shown in figure 1.10. Line defects are mostly due to misalignment of ions or presence of vacancies along a line that can be weaken or strengthen solids. When lines of ions are missing in an otherwise perfect array of ions, an edge dislocation appeared which is responsible for the ductility and malleability. In fact movement of edge dislocation often results hammering and stretching of materials. Movements of dislocations give rise to their plastic behavior. Line dislocations usually do not end inside the crystal, they form loops or end at the surface of a single crystal.
Defects in Crystalline Solids
Published in Bankim Chandra Ray, Rajesh Kumar Prusty, Deepak Nayak, Phase Transformations and Heat Treatments of Steels, 2020
Bankim Chandra Ray, Rajesh Kumar Prusty, Deepak Nayak
In crystalline solids, line defect refers to those defects producing lattice distortion around a line. This class of defect is very important as far as mechanical properties of the material are concerned. The one-dimensional or line defect in case of crystalline solids is known as dislocation. Dislocations may be produced during solidification or during plastic deformation or by vacancy condensation. Presence of dislocations allows plastic deformation of the material far below the fracture stress of the material without disturbing the crystal structure. Dislocation line is defined as the boundary between the disturbed and undisturbed portion of the crystal. Another important characteristic of dislocation is the Burgers vector. The Burgers vector is the vector having slip direction, and magnitude is the interatomic distance between two consecutive atoms along the slip direction. Based on the geometry of dislocation, it is divided into two groups: (i) edge dislocation and (ii) screw dislocation.
Effect of Oxygen Ion Irradiation on Nb-1Zr-0.1C Alloy Characterized Using X-Ray Diffraction Line Profile Analysis
Published in Nuclear Science and Engineering, 2023
Argha Dutta, Apu Sarkar, Sandip Bysakh, Uttiyoarnab Saha, N. Gayathri, Santu Dey, P. Mukherjee
There are mainly three types of defects that can be produced in the material due to irradiation.17 The first type of defects consists of point defects, i.e., interstitials, vacancies, etc. The second type of defects includes dislocations, large clusters, loops, etc. The third type of defects comprises the surface defects, i.e., stacking faults, twin boundaries, etc. All these defects create lattice disturbance, which affects the periodicity of the crystal. Among these three types of defects, the second type of defects directly affects broadening of the X-ray diffraction peak.42 The first type of defects creates diffuse scattering far from the Bragg peak whereas the third type of defects is responsible for peak shift or may introduce asymmetry in broadening of the XRD peaks. In this study, qualitative information of the second type of defects was extracted from broadening of the XRD peaks.
Defects, diffusion and dopants in the ceramic mineral “Lime- Feldspar”
Published in Journal of Asian Ceramic Societies, 2021
Sivanujan Suthaharan, Poobalasuntharam Iyngaran, Navaratnarajah Kuganathan, Alexander Chroneos
Defects play a significant role in mechanical and diffusion properties of a material. A series of isolated point defects (vacancies and interstitials) were calculated and then they were combined to calculate Frenkel and Schottky defect formation energies. The anti-site defects were also considered in the form of isolated and cluster. Impurity defects (e.g., were considered separately and their defect energies were combined to calculate the anti-site (isolated) reaction energy. In the case of cluster form, both defects were considered simultaneously. The difference between the defect energies {E (cluster) ‒E (isolated)} is defined as binding energy. Defect reaction energies as written using Kröger-Vink notation [37] are shown inequations 1–14.
A non-singular continuum theory of point defects using gradient elasticity of bi-Helmholtz type
Published in Philosophical Magazine, 2019
Among the important problems widely addressed in the mechanics of defects is the determination of the elastic state of point defects. Defects (dislocations and point defects) are always present in crystalline solids. The interaction between defects can change considerably many properties of crystals. In addition to dislocations, which are line defects, point defects are also important defects in crystals [1–3]. Point defects can exist in different configurations such as vacancies, interstitials, substitutional atoms, and foreign atoms. The fields of point defects play an important role in determining the physical properties of solids. They cause volume change and interact with dislocations if dislocations climb. Point defects play a major role in many physical problems such as X-ray scattering, internal friction phenomena, aggregation of defects, dislocation locking and various diffusion processes [1,4]. Nowadays, the fields caused by point defects are important in computer simulations of defect mechanics and discrete dislocation dynamics. Atomistic and ab initio simulations of point defects and their interaction with dislocations, including a comparison between atomic simulations and classical elasticity theory, are reported in [5–7].