Ab initio calculations and experimental study of piezoelectric Y In1−N thin films deposited using reactive magnetron sputter epitaxy

Abstract

By combining theoretical prediction and experimental verification we investigate the piezoelectric properties of yttrium indium nitride (Y x In 1−x N). Ab-initio calculations show that the Y x In 1−x N wurtzite phase is lowest in energy among relevant alloy structures for 0 ≤ x ≤ 0.5. Reactive magnetron sputter epitaxy was used to prepare thin films with Y content up to x = 0.51. The composition dependence of the lattice parameters observed in the grown films is in agreement with that predicted by the theoretical calculations confirming the possibility to synthesize a wurtzite solid solution. An AlN buffer layer greatly improves the crystalline quality and surface morphology of subsequently grown Y x In 1−x N films. The piezoelectric response in films with x = 0.09 and x = 0.14 is observed using piezoresponse force microscopy. Theoretical calculations of the piezoelectric properties predict Y x In 1−x N to have comparable piezoelectric properties to Sc x Al 1−x N.

Enhanced Piezoelectric Response of AlN via CrN Alloying

“…The wurzite phase is found to be favorable up to x = 0.25, beyond which rocksalt alloys are stable; this wurzite to rocksalt phase transition point is consistent with previous experimental observations and other theoretical predictions. 19,20 We have compared the mixing enthalpy of the Cr x Al 1−x N alloys with that of several other common wurzite-based nitrides, 13,15,18,36,37 Sc x Al 1−x N, Y x Al 1−x N, and Y x In 1−x N, with the results shown in Figure 2(b). The mixing enthalpies are positive for all cases, meaning that the alloying of AlN or InN with their respective end members is an endothermic process.…”

Characterization of Elastic Modulus Across the (Al1–<italic>x</italic>Sc<italic>x</italic>)N System Using DFT and Substrate-Effect-Corrected Nanoindentation

“…Computational studies suggest that such increases in Al 1−x Sc x N and related materials stem from mechanical softening of the wurtzite phase and may be associated in part with proximity to a phase boundary [13]- [16]. The elastic properties of these alloy systems are receiving less attention; experimental studies only minimally cover the range of 5%-30% Sc [17], [18], computational work does not extend beyond 50% Sc [13], [15], [19], and no previous study provides direct comparison between the computed and measured elastic constants.…”

Tuning the piezoelectric and mechanical properties of the AlN system via alloying with YN and BN

“…solid solutions between two compounds, have been extensively investigated for use in electromechanical applications. [6][7][8][9][10] Most of these alloys have large miscibility gaps, which makes them less appealing for applications where mechanical stability is an important figure of merit. The presence of miscibility gaps is not particularly restrictive, since current non-equilibrium processing techniques allow for fabricating pseudo-binary alloys in which one can seek a given functionality by, e.g., changing composition (often through the miscibility gaps) so as to optimize piezoelectric coefficients, stiffness, electromechanical coupling constants, or electronic properties.…”