Trends in the high-temperature heat capacities of ternary chalcopyrite semiconductors

Abstract

The anharmonic contribution to the heat capacity of any chalcopyrite semiconductor AIBmC vl or AnBwC v is evaluated. It is shown that the degree of lattice anharmonicity decreases with increasing atbmic weight of the constituen! atoms of the compounds, and there is no essential difference in the degree of lattice anharmonicity of the two groups of compounds. Except for CdGeAs2, the trend in the Grfineisen constants is the same.In studies of the thermal expansion behaviour of the ternary compounas AIBIIIcVI (A I ~ Cu, Ag; BIII ~ AI, Ga, In; C vI = S, Se, Te), it has been established that the thermal expansion coefficients remain temperaturedependent up to the highest temperatures investigated ([1-3 ] and references cited therein). In terms of the perturbation theory, this means that higherorder anharmonic contributions to the interatomic forces play an important role in establishing the thermal properties of these compounds. In the AIIBIV cV compounds (A ll ~ Zn, Cd;B W = Si, Ge, Sn; C v = P, As), which also crystallize in the chalcopyrite structure, the situation seems to be different from that in the semiconductors AIBmc vI. In most cases, temperature-independent thermal expansion coefficients have been found at elevated temperatures ([4] and references cited therein), the only exception being CdGeP2, which exhibits a thermal expansion behaviour like that in the compounds AIBIIIcVI [5]. These results suggest the conclusion that lattice anharmonicity effects are generally less pronounced in the compounds AHB Iv C v than in the semiconductors AIB nI C vI. It was the aim of the present work to acquire further insight into the lattice anharmonicity effects of these ternary compounds by measuring and analysing their heat capacities at elevated temperatures. ExperimentalThe compounds AIBmC vI used in the experiments were prepared by fusion of stoichiometric mixtures of the elements, while the semiconductors AIIB rv C v were grown from the vapour phase. X-ray analysis was used to confirm the structures and the lattice parameters of the compounds and to

Micro-Raman spectroscopy studies of bulk and thin films of CuInTe2

“…It can be seen from the above equations that the rise in temperature depends sensitively on the incident beam radius. The values of the thermal conductivity (κ ∼ 3.4 W m −1 K −1 ) and heat capacity (c v ∼ 100 J (mol) −1 K −1 ) of CuInTe 2 may be taken from the reported data [36,37]. Assuming the beam radius to be 0.9 μm and the absorption coefficient of the CuInTe 2 film to be 2 × 10 7 m −1 at 488 nm, the increase in temperature at the center of the beam spot on the film surface (z = r = 0), after 1 s for a laser beam power of 20 mW is calculated to be 390 K. Further, on the film surface (z = 0) the increase in temperature has been found to fall to half of its value (195 K) at a radial distance of 1.6 μm.…”