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Basics of Growth Techniques Used for Bulk Single Crystals of Transparent Semiconducting Oxides
Published in Zbigniew Galazka, Transparent Semiconducting Oxides, 2020
The Czochralski method is nowadays used worldwide to grow different types of single crystals: metals, elemental semiconductors, compound semiconductors, halides, and oxides. As large as 450 mm diameter semiconductor and halide crystals and 200 mm diameter oxide crystals (sapphire, Bi4Ge3O12) are grown nowadays by the Czochralski method. Large crystal diameter, high structural quality, and low production costs per volume unit make the Czochralski method one of the most frequently used technique at research and industrial levels for growing a diversity of single crystals. Among TSOs, the Czochralski method was successfully applied for 13-Ga2O3 [185–189] and Ga-based spinel single crystals [168, 169].
Physical Properties of Crystalline Infrared Optical Materials
Published in Paul Klocek, Handbook of Infrared Optical Materials, 2017
James Steve Browder, Stanley S. Ballard, Paul Klocek
Notes: Sodium chloride, the natural form of which is ordinary rock salt, polishes easily, and, although hygroscopic, can be protected by evaporated coatings and plastics; selenium films have been used successfully. It is soluble in glycerin. Synthetic single crystals can be grown by the Czochralski method. Sodium chloride is used for IR spectrometer window cells and laser windows. Diameters as large as 12 in. are available.
Impact of germanium doping on the mechanical strength of low oxygen concentration Czochralski silicon wafers
Published in Philosophical Magazine, 2021
Junnan Wu, Robert W. Standley, Katharine M. Flores
Germanium is a promising candidate for strengthening silicon, as it is electrically neutral and forms a solid solution with silicon at all concentrations. Previous work reported that Ge can retard dislocation motion in high oxygen concentration (10–11 × 1017 atoms/cm3) silicon wafers by enhancing oxygen precipitation [22], and can lock dislocations when co-doped with a high concentration of boron [23]. Yonenaga [24,25] has shown that Ge doping at high concentration, above 1 × 1020 atoms/cm3, only slightly increases the critical shear stress for generation of dislocations compared to that of undoped samples. The oxygen concentrations in those experiments were relatively high compared to that of the high resistivity silicon wafers grown by the Czochralski method for radio frequency applications, such that oxygen locking is still a dominant locking mechanism. It was also shown that Czochralski growth of single crystalline silicon ingots doped with very high Ge concentration (> 2 × 1020 atoms/cm3) leads to serious crystal growth problems, such as cellular growth and slip generation [26]. In our work, the Ge concentration has been reduced moderately compared to that used by Yonenaga [24,25], to ∼ 7–9 × 1019 atoms/cm3. This is both to avoid the crystal growth issues in the commercial growth of long crystals, (i.e. at a high final fraction solidified) and also to mitigate the manufacturing cost of such crystal, as high purity Ge is very expensive. However, the concentration is still greater than that where Fukuda and Osawa reported Ge dislocation locking in CZ Si (6 × 1019 atoms/cm3) [27]. We investigate here whether Ge has a more significant impact on dislocation locking when the oxygen concentration and its associated dislocation locking are greatly reduced. Such an impact could arise from the dislocation locking of the Ge atoms alone, or from interactions between Ge and interstitial oxygen as proposed by others [22].
Tensoelectric properties irradiated by the fast electrons n-Ge single crystals
Published in Radiation Effects and Defects in Solids, 2023
S. V. Luniov, M. V. Khvyshchun, D. A. Zakharchuk, V. T. Maslyuk
The measurement of tensoresistance and Hall constant was been performed for n-Ge single crystals which were uniaxially deformed along the crystallographic direction [100] at room temperature. With such uniaxial deformation, there will be no deformational redistribution of electrons between minima of the germanium conduction band, which effects on the reduction of electron mobility [14, 16]. The investigated germanium single crystals were grown by the Czochralski method and doped by the antimony impurity, with the concentration of . The electron irradiation was carried out on an M-30 microtron at room temperature by the flows of the electrons of , , and with the energy of . The investigated n-Ge single crystals did not change their conductivity type at the irradiation flows , and were converting in p-type for the flows . In works [24, 25], on the basis of measurements of the Hall effect, we have obtained temperature dependences of the Hall mobility for the same undeformed and uniaxially deformed n-Ge single crystals, irradiated by the electrons with the energy of and a flow of . Our theoretical calculations of these dependences made it possible to establish that, in addition to the mechanisms of phonon scattering and scattering of electrons on the ions of shallow donors, a significant contribution to the value of electron mobility is also made by the mechanisms of scattering on the different charge states of A-centers, modified by two interstitial germanium atoms, on the regions of disordering and the large-scale potential. The analysis of the temperature dependences of the Hall constant carried out by us in [26] showed that, both before and after n-p conversion, in the investigated n-Ge single crystals after electron irradiation by different flows will be created electrically active defects with the energy levels of and which belonging to A-centers, modified by two interstitial germanium atoms ( complexes). Also, the obtained results in this work are confirmed by measurements at room temperature of IR absorption spectra for single crystals n-Ge irradiated by different electron flows (Figure 1).
Self-powered photo-thermo electrochemical sensor for harvesting of low photo thermal energy
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2020
Faheem Ali, Hafiz Muhammad Salman Ajmal, Waqar Khan
Figure 3 shows the surface morphology and chemical information of our n-InAs and Zn electrode materials used for the n-InAs/OD-solution/Zn sensors. As shown in SEM micrographs of Figure 3 (left), n-InAs exhibits quite smooth surface while the counter electrode Zn has much rougher pattern along the surface direction. As shown in EDS spectra of Figure 3(right), there are two major elemental components of indium (In) and arsenic (As) with small amount of Te dopants in the photo-anode material of InAs, while no other significant contaminants were observed except little amount of oxygen. The weight percent (wt. %) concentrations of elemental species in InAs compound and Zn are shown in Table 1. Crystalline quality and growth orientation of each electrode material were investigated by XRD. Figure 4(a) shows the XRD θ–2θ pattern of n-InAs, a single high intensity peak along (111) crystal plane was observed. This result reveals that n-InAs electrode material was grown along (111) direction. On the other hand, as shown in Figure 4(b), various peaks from (002), (100), (101), and (102) planes were observed from the metallic Zn where the diffraction from each plane corresponds to the 2θ angles of 36.2°, 38.9°, 43.1°, and 54.2°, respectively. The most intense peak with very narrow peak width was obtained from (101) plane at 2θ = 43.1°, and this indicates our polycrystalline zinc electrode is preferentially aligned to this planar direction. The observed diffraction patterns and EDS results are well-matched with the earlier reported studies of electrode material in organic dye-electrolyte cells (Ali et al. 2015; Ahmad et al. 2016). The preparation and purification of high crystalline InAs material in the ingot form by Czochralski method is a formidable task as compared to synthesis process of other crystal materials, i.e. InSb or InP crystals for these kinds of applications. In Czochralski method, we generally use a crystalline seed to grow the ingot of InAs and molten form of In and As in the crucible. Although high purity of In can be available readily before putting into crucible of Czochralski equipment. However, the purification of As is relatively difficult due to unavoidable impurities present in As; for example, S or Te and are difficult to remove completely from As in the fractional sublimation process used for its purification. Therefore, during the crystal growth process of InAs by Czochralski pulling apparatus, the doping of Te was carried out as a dopant material in (111) plane. The plane (111) is due to the seed crystal orientation of InAs growth. Furthermore, to get less shinny surface images by controlling the charging effect in SEM analysis, we have done the Cu sputtering on the surface of the investigated materials. So Oxygen may contaminate with sputtered-metal and behaves as the impurity traces.