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Solid State Background
Published in P.J. Gellings, H.J.M. Bouwmeester, Electrochemistry, 2019
Isaac Abrahams, Peter G. Bruce
The hexagonal close-packed form of ZnS known as wurtzite (Figure 3.22) consists of hep S2− ions with Zn2+ in half the tetrahedral sites. The sulfide coordination is also tetrahedral. The comer-sharing Zn tetrahedra all point in the same direction. The structure is commonly adopted by II–VI and III–V solids such as CdS and InN. Other compounds with the wurtzite structure include ZnO (zincite), BeO, CdSe, AgI, MgTe, and MnS.
Semiconductor Materials
Published in Jerry C. Whitaker, Microelectronics, 2018
Although the common semiconductor materials share this basic diamond/zinc blende lattice structure, some semiconductor crystals are based on a hexagonal close-packed (hcp) lattice. Examples are CdS and CdSe. In this example, all of the Cd atoms are located on one hcp lattice whereas the other atom (S or Se) is located on a second hcp lattice. In the spirit of the diamond and zinc blende lattices, the complete lattice is constructed by interpenetrating these two hcp lattices. The overall crystal structure is called a wurtzite lattice. Type IV–VI semiconductors (PbS, PbSe, PbTe, and SnTe) exhibit a narrow bandgap and have been used for infrared detectors. The lattice structure of these example IV–VI semiconductors is the simple cubic lattice (also called an NaCl lattice).
Systems Based on GaN
Published in Tomashyk Vasyl, Ternary Alloys Based on III-V Semiconductors, 2017
Thermodynamic, structural, and electronic properties of wurtzite Ga1–xInxN alloys are studied by combining first-principles total energy calculations with the generalized quasi-chemical approach, and compared with previous results for the zinc blende structure (Caetano et al. 2006). It was observed that the results for the wurtzite structure are not significantly different from the ones obtained for the zinc blende structure. The calculated phase diagram of the alloy shows a broad and asymmetric miscibility gap, as in the zinc blende case, with a similar range for the growth temperatures, although with a higher critical temperature. A value of 1.44 eV for the gap bowing parameter was found.
SILAR-deposited manganese doped zinc oxide thin films for NO2 gas detection applications
Published in Phase Transitions, 2023
Nabeel T. Abood, Pradip B. Sable, Gopichand M. Dharne
In this study, we successfully synthesised of Mn-doped ZnO thin films by using the SILAR method. The characterisation of the structural, morphological, elemental and optical characteristics of the Mn-doped ZnO was conducted using XRD, SEM, EDS, FTIR, and UV-Vis. All samples show hexagonal wurtzite crystal structures, according to XRD analysis. The size of the crystallite, the lattice constants, and the FWHM, point to Mn ions being substituted at the Zn site of the ZnO lattice. The FESEM images confirm numerous spherical particles all over the surface of the Mn doped ZnO film. The agglomeration of tiny grains into bigger clusters is seen, and this agglomeration is found to be increased with Mn doping. Zn, Mn, and oxygen are present across the scanned region of the samples, according to EDS spectra. FT-IR study confirms the proper incorporation of Mn ions in the Zn site of ZnO. UV–VIS analysis shows that the increase in Mn concentration causes a slight shift of the absorption edge and a decrease in the band gap. The response of Mn/ ZnO to 40 ppm of NO2 gas increase with increment of Mn concentration. The highest response was found to be 1.97 for the sample Zn0.92 Mn0.08 O, with response/ recovery time 12.75/ 122 s. The response of Zn0.92 Mn0.08O to different NO2 gas concentrations increases as the NO2 gas concentration increases.
Machine-learning of piezoelectric coefficients for wurtzite crystals
Published in Materials and Manufacturing Processes, 2023
Sukriti Manna, Mingyuan Wang, Adrian Barbu, Cristian V. Ciobanu
Since the work of von Hippel on barium titanate,[1] piezoelectric materials have steadily risen in prominence in terms of enabling fundamental science as well as a hole host of applications. Today, piezoelectrics are widely used as materials for surface and bulk acoustic resonators,[2,3] accelerometers,[4] oscillators,[5] micro-electromechanical systems (MEMS), or resonators in energy harvesting systems.[6] Such widespread use has been enabled by a whole host of desirable properties, for example, low cost of synthesis, high thermal conductivity, CMOS compatibility, high mechanical stiffness and others. There are only a few classes of piezoelectrics that cover most applications, prompting research into developing a wider class of materials to enable novel technological progress, especially for electronic devices, smart phones and other telecommunications technologies.[7–9] Currently, wurtzite-based materials (i.e., AlN) are prominently featuring in some of these applications, especially in broadband communications.[10,11] Given the limited number of wurtzite structures, systematic efforts have been dedicated to understand how to enhance the piezoelectric coefficients of these wurtzites, especially by alloying.[12–14] It is by now established that substitution of Al with larger ions (e.g., Cr, Sc, Y) can lead to notable increases in the axial coefficient e33.[12–18] The other coefficients so far have received significantly less attention than e33, although one can envision applications where these coefficients may play an enabling role. Other avenues for continuing to develop or discover piezoelectric materials may include looking at the larger space group to which the wurtzite-structured AlN belongs, and increasing the combination of alloying cations or anions.