Rev.Adv.Mater.Sci. (RAMS)
No 2, Vol. 21, 2009, pages 183-191

CORRELATION BETWEEN OVERALL ELASTIC
STIFFNESS, BULK MODULUS AND INTERATOMIC
DISTANCE IN ANISOTROPIC MATERIALS:
SEMICONDUCTORS

Mohamed Gaith and Imad Alhayek

Abstract

In this study, the correlation between macroscopic and microscopic properties of the IIIV semiconductor compounds CdX (X=S, Se, Te) is investigated. Based on constructing orthonormal tensor basis elements using the form-invariant expressions, the elastic stiffness for cubic system materials is decomposed into two parts; isotropic (two terms) and anisotropic parts. A new scale for measuring the overall elastic stiffness of these compounds is introduced and its correlation with the calculated bulk modulus and lattice constants is analyzed. The overall elastic stiffness is calculated and found to be directly proportional to bulk modulus and inversely proportional to lattice constants. A scale quantitative comparison of the contribution of the anisotropy to the elastic stiffness and to measure the anisotropy degree in an anisotropic material is proposed using the Norm Ratio Criteria (NRC). It is found that among these compounds CdS is the nearest to isotropy (or least anisotropic) while CdTe is the least near to isotropy (or nearest to anisotropic). The norm and norm ratios are found to be very useful for selecting suitable materials for optoelectric devices, transducers, modulators, and acousto-optic devices.

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