The semiconductor ZnO has gained substantial interest in the research community in part because of its large exciton binding energy (60meV) which could lead to lasing action based on exciton recombination even above room temperature. Even though research focusing on ZnO goes back many decades, the renewed interest is fueled by availability of high-quality substrates and reports of p-type conduction and ferromagnetic behavior when doped with transitions metals, both of which remain controversial. It is this renewed interest in ZnO which forms the basis of this review. As mentioned already, ZnO is not new to the semiconductor field, with studies of its lattice parameter dating back to 1935 by Bunn [Proc. Phys. Soc. London 47, 836 (1935)], studies of its vibrational properties with Raman scattering in 1966 by Damen et al. [Phys. Rev. 142, 570 (1966)], detailed optical studies in 1954 by Mollwo [Z. Angew. Phys. 6, 257 (1954)], and its growth by chemical-vapor transport in 1970 by Galli and Coker [Appl. Phys. ...

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A comprehensive review of zno materials and devices

Coefficients of thermal expansion α‖c and α ⊥ c between 4 and 800°K have been measured for zinc oxide using an interferometric and a capacitance method. Thermal properties of wurtzite lattices (two coefficients of thermal expansion and a pyroelectric constant) can be described in terms of three thermal equations of state. Two mechanical and one electrical Gruneisen parameters are defined and their temperature dependence is calculated from experimental results. The high- and low-temperature limits of the Gruneisen parameters are compared with results obtained in other experiments. The values predicted from a rigid ion model are discussed.

Thermal Expansion of Silicon and Zinc Oxide (I)

The temperature dependence of the lattice parameters of ZnO was measured by x‐ray powder‐diffraction methods. Retrograde behavior was found to occur perpendicular to the c axis at 93°K. Lattice parameters at 4.2°K were a0=3.24826±0.00015A, c0=5.2033±0.0018 A. These results are compared with those for some other II‐VI compounds.

Lattice parameters of ZnO from 4.2° to 296°K

http://www.rsc.org/suppdata/CC/b7/b700082k/b700082k.pdf

Supramolecular synthon polymorphism in 2 : 1 co-crystal of 4-hydroxybenzoic acid and 2,3,5,6-tetramethylpyrazine.

A structural model of ZnO in the cumulant-expansion formalism has been studied with X-ray intensities measured on a spherical crystalat293 and,473 K. In the least-squares refinements, the thermal vibrations appear isotropic for both atomic species at the two temperatures investigated. The equivalent isotropic temperature-factor B- of Zn varies from 0b581(2) to 0.892(5); that of O, from 0.572(9) to 0.829(19) A2. The only structural parameter, z of O, shows no significant change: 0.3821(l) at 293 K and 03820Q) at 473 K. At both temperatures, the measured amplitudes of reflections 35./ and 07./ (same 4 are different: lF(35./) | is lalger or smaller than lF(0?.I)l according as / is even or odd, while both reflections should have the same amplitude, on the assumption of spherical electrondensity distributibns, if the atoms vibrated with harmonic motions. The observed differences are interpreted with nonzato \11for the third-order cumulant: c111 is positive for atoms at tA,24, Z and negative for atoms at ,,, tA, r/2 + 2,. Least-squares analyse_s of higher-order reflections give crrr = 3.0(0.5)_x l0-' for the 293 K data and l0.l(1.1) x lG: forthe 473Kdata,. Theparameterclll is directly compared with an effective potential one-particle

ANHARMONIC THERMAL VIBRATIONS IN Zno

Lattice parameters of zinc oxide have been determined accurately at different temperatures between 27°C and 619°C. These data have been processed to evaluate the temperature variation of the coefficients of thermal expansion αa and αc and the results could be represented as follows: αa = 6.05 × 10−6 + 2.20 × 10−9t + 2.29 × 10−12t2°C−1 // αc = 3.53 × 10−6 + 2.38 × 10−9t + 9.24 × 10−14t2°C−1 where t is the temperature in °C.

A. A. Khan

Papers

X-ray determination of thermal expansion of zinc oxide