Polarization, piezoelectric constants, and elastic constants of ZnO, MgO, and CdO

Abstract

We report first-principles density functional calculations of the polarizations, piezoelectric stress constants, and elastic constants for the II-VI oxides MgO, ZnO, and CdO in the wurtzite structure. Using our pseudopotential selfinteraction corrected implementation of density functional theory, we obtain polarization values of ÿ0.060, ÿ0.022, and ÿ0.10 C/m 2 , and piezoelectric constants, e 33 (e 31 ) of 1.64 (ÿ0.58), 1.34 (ÿ0.57), and 1.67 (ÿ0.48) C/m 2 for structurally relaxed MgO (with its in-plane lattice parameter fixed to that calculated for ZnO), ZnO, and CdO, respectively. The large polarization gradients between the end-point compounds in the MgO-ZnO-CdO system augur well for the production of large internal fields in ZnO-based polarization field effect transistors.

Evolution of local structures in polycrystallineZn1−xMgxO(<

“…An earlier DFT study has reported an extremely distorted hexagonal structure (c/a = 1.20, u = 0.5) for the wurtzite MgO, in which Mg sits on a mirror plane and has a bi-pyramidal coordination. 46 However recent studies, independently conducted by Janotti et al 47 and Gopal and Spaldin, 48 have reported c/a = 1.51 and u = 0.398. More relevant to our experimental work, Malashevich and Vanderbilt performed the geometry optimization of Zn 1−x Mg x O supercells (x = 0, 49 They showed that the c/a decreases with increase of Mg content, and u(Mg) is larger than u(Zn) in all the supercell compositions.…”

Work Function Estimation of Bismuth Doped ZNO Thin Film

“…The Bismuth doped ZnO sol of concentration 0.7 M have been prepared using precursor zinc acetate dehydrate (Zn(CH 3 COO) 2 .2H 2 O), isopropanol (solvent) and stabilizing agent diethanolamine (DEA). The molar proportion of zinc acetate dehydrates and stabilizer DEA was kept at 1:1.…”

“…As far as the future of the semiconductor devices is concerned, ZnO has a major role to play in it as it is versatile and has interesting properties like resistivity control over the range of 10 −3 -10 -5 Ω-cm, transparency in the visible range, high electrochemical stability, direct band gap (3.3 eV), absence of toxicity and abundance in nature [1][2]. Therefore, it can be stated that versatility of ZnO ranges from optical, electrical, piezoelectricity, ferromagnetic to gas sensing properties [3][4][5].…”

Atomic-scale origin of piezoelectricity in wurtzite ZnO

“…In particular, wurtzite ZnO has been extensively studied by virtue of its high piezoelectric tensor. [16][17][18][19][20] Moreover, ZnO nanostructures show a variety of different morphological configurations that include nanowires, 21 nanobelts, 22 nanosprings, 23 nanorings, 24 nanobows, 25 and nanohelices. 26 Among these nanostructures, nanowires exhibit remarkably enhanced piezoelectric responses.…”