C. Verie, EXPECTED PRONOUNCED STRENGTHENING OF II-VI LATTICES WITH BERYLLIUM CHALCOGENIDES, Materials science & engineering. B, Solid-state materials for advanced technology, 43(1-3), 1997, pp. 60-64
To our knowledge, the suggestion, based on material calculation, of ti
le utilization of beryllium chalcogenides-based materials, BeX(X = S,
Se, Te). as novel II-VI epitaxial layers, was proposed recently in pub
lished communications (C. Verie, Condensed Matter Meet. JMC-4. Rennes:
France, Aug. 31-Sept. 2, 1994, published in Abstract Booklet, French
Physical Society, Paris, 1994; C Verie, in B. Gil and R.L. Aulombard (
eds.), Semiconductor Heteroepitaxy, Growth, Characterization and Devic
e Applications, World Scientific. Singapore, 1995, pp. 73-78.). In the
present work, this is discussed in the context of the unsolved questi
on of appropriate long lifetime CW operation in (Zn, Cd)(S, Se)-based
blue laser at T greater than or equal to 300 K. The shear modulus C-s
= (C-11 - C-12)/2 is identified to be a key structural signature of th
e material. Making use of the Harrison bond-orbital model, the calcula
tion of C-s leads to a simple semi-empirical expression. Its plot vers
us the Harrison covalency scale-based Variable demonstrates good agree
ment with all experimental data for the tetra-coordinated semiconducto
rs. Prediction capabilities are exploited: (i) the alloys (Zn, Cd)(S,
Se) belong to a cluster of materials having an ionicity-induced soften
ing of the lattice; (ii) the problem of high-quality epitaxy using a c
ompound with ionicity values above the critical one, e.g., MgX (X = S,
Se); (iii) the BeX samples exhibit C-s of the order of or even higher
than, that of Si or GaAs. This work suggests novel possibilities for
hardening the lattice in II-VI alloys, leading to a 'covalency enginee
ring' of blue laser epilayers. (C) 1997 Elsevier Science S.A.