ELSEVIER October 1996 Materials Letters 28 (1996) 297-300 Microhardness, Debye temperature and bond chalcopyrite compounds C. Rinc6n *, M.L. Vale&Gil ionicity of ternary zyxwvutsrq Centro de Estudios de Semiconductores, Departamento de Ffsica, Facultad de Ciencias, Universidad de Los Andes, Merida, Venezuela Received 15 February 1996; accepted 3 March 1996 Abstract By analyzing the published data for the microhardness H of the A”B’“C~ and A’B’uC~’ chalcopytite-structure semiconductors, a linear relation between this parameter and its corresponding Debye temperature is found. On the basis of this result and taking into account that H for these compounds depends on the intrinsic defect equilibrium of the crystals, the microhardness of nearly stoichiometric samples is estimated. It is also found that H decreases as the ionicity increases and tends to vanish at fii = 0.79. This is the critical ionicity that separates the four-fold chalcopyrite compounds with those of the six-fold structures. &words: Ternary semiconductors; Chalcopyrite structure; Microhardness; Debye temperature; Bond ionicity The microhardness parameter zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA H, that character- izes the mechanical properties of solid state surfaces, is of considerable importance. This is because it is a measure of the properties of the material that change by surface treatment [ll. The microhardness of the A”B’“C; chalcopyrite semiconductors has been studied by several authors [2,3]. From the analysis of these results reliable values of H have been esti- mated [4]. However, in the case of the A’B”‘Cy’ chalcopyrites, the values of H reported by various authors differ considerably [3,5]. Furthermore, all attempts to find empirical models to calculate this parameter for these compounds [5,6] give values of H that are in disagreement with the reported data. It * Corresponding author has also been found that in nearly stoichiometric materials the hardness depends on the conduction type and the intrinsic defect equilibrium of the crys- tals [7]. It was suggested that On may be related to H by an expression based on a simple lattice model [3] @ zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPO D a ~Wvt/6~-1/2 (1) where M is the mean atomic weight per lattice site and V the mean atomic volume. Such an expression has been used to estimate 0, of the ternary chalcopyrite compounds from its ex- perimental microhardness data [3]. However, by ana- lyzing the recent data of H in these materials we found that it is directly related to the Debye tempera- ture, i.e. H - 0,. To show this we plot in Fig. I, as a function of O,, the experimental values of H for the A”Bt”C~ compounds compiled in Ref. [4] and 00167.577X/96/$12.00 Copyright 0 1996 Elsevier Science B.V. All rights reserved. PII SO167-577X(96)00073-0