Structure chalcopyrite

The isotropic chemical shift, the trace of the chemical shift tensor, is one of the basic NMR parameters often measured for both spin-1/2 and quadrupolar nuclei. The CSA can also be measured in non-cubic environments, such as the n3Cd nuclei experience in the chalcopyrite structure of crystalline CdGeAs2 [141] or CdGeP2 [142], and the 31P nuclei in the latter compound [142], Although the isotropic chemical shift can be measured from the NMR spectrum of a static powder because the CSA is zero in many cases because of cubic symmetry of the lattice, improved resolution is obtained by using MAS to remove dipolar couplings. Two particular areas where the isotropic chemical shifts have proven very informative will now be discussed, semiconductor alloys and semiconductor polytypes. 

Changes in the lineshapes of static 63Cu NMR peaks at high temperatures (from room temperature to 550° C) have been observed in the chalcopyrite structure... 

Evidence of a more ordered chalcopyrite structure can be shown in Fig. 6.26, where the (101) and (211) diffractions at 17.9° and 37.3°, respectively, can be clearly shown in the annealed film. Another characteristic of the chalcopyrite structure not shown in the sphalerite structure is the peak splitting in... 

Ternary semiconductors of the I-III-VI groups (I = Cu, Ag III = Al, Ga, In VI = S, Se, Te) with a chalcopyrite structure have attracted attention as new functional materials for solar hydrogen production [164-167]. With the aim of capturing a larger fraction of solar light, solid solutions of two or more sulfides were prepared. A... 

CuInSi (and, even more, CuInSei) are strong candidates for thin-film photovoltaic cells. For this purpose, the chalcopyrite structure (which is an ordered lattice) is preferred over the disordered, zincblende form. Due to the large absorption coefficients of these materials, a 1-iJim-thick film is more than enough to absorb almost all the suprabandgap radiation. Somewhat thicker films are generally used, due to problems of pinholes, which commonly occur in thinner films. A number of methods have been used to deposit these films. Surprisingly, very few (published) attempts have been made to deposit them by CD. 

The copper, copper-iron, and the silver sulfides are more complex than the sulfides discussed previously, containing several cations or cation sites in their structures. Thus chalcopyrite (CuFeSj), although having a fairly simple structure based on that of sphalerite, but with Cu and Fe alternately replacing Zn atoms, contains both Cu+ and Fe + in regular tetrahedral coordination (as indicated by neutron diffraction and Moss-bauer studies see Vaughan and Craig, 1978). A family of more than thirty synthetic compounds with the chalcopyrite structure is known, and their properties have been studied because of potential applications as semiconductors. Miller et al. (1981) have reviewed the crystal structures, vibrational properties, and band structures of these materials. 

According to the analysis of the enthalpies of formation, BeGeAs2 is stable in the body centered tetragonal chalcopyrite structure with 16 atoms in the unit cell [1,5]. We have constructed 64 atoms 2x2x1 supercell where two atoms of II or... 

X-Ray diffraction studies show that all members of the CuGa xFexS2 series (O x l.O) crystallize with the chalcopyrite structure.549 When x = 0.025 the magnetic moment for Fe approaches the spin-only value (5.92 B.M.). 

The preparation and characterization of the two phases Caio- Si,2-2 As,(, and Caio, Si]2- Pi6 (0.66 X 2.50) have been described.Their structures are isotypic and crystallize with monoclinic symmetry, of space group they may be related to a slightly distorted NaCl-type. Their unit-cell parameters are included in Table 27. A comparison of the different methods of crystal growth of ZnSiP2, ZnSiAs2, and CdGeAs2 (chalcopyrite structures) has also been undertaken. " ... 

The most prevalent ternary chalcopyrite materials are jo-type Cu(In Ga)(S Se)2 (CIGS), which crystallize in the tetragonal chalcopyrite structure and are used in the photovoltaic modules. The complexity of the phase diagrams for Cu-III-VI materials results in a large number of intrinsic... 

CdGePg, formed from the elements at 800 °C, has a strictly ordered tetragonal chalcopyrite structure having a symmetry that is almost tetragonal. A glassy disordered structure can be obtained through rapid quenching of the molten material. 

Chalcopyrite Structure Compounds (Strukturbericht symbol Elj, Space Group I 4 2d-D )... 

The examples given show that, in comparisons of the properties of compounds in the liquid and the solid states, one should not employ materials with the same structures but those which are formed in a similar way. Thus, the activation energy of the conductivity in the molten state is practically equal to the forbidden band width in the crystalline state for compounds with different structures (orthorhombic Bi2S3 and chalcopyrite CdSnAs2) but this is not true for the two compounds with the same chalcopyrite structure (CdSnAs2 and CuInTe2). 

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