Unlocking AlN Piezoelectric Performance with Earth‐Abundant Dopants

Abstract

The increasing demand for high‐performance piezoelectric materials and toxicity and thermal stability issues of the widely used lead zirconate titanates (PZT) have spurred a search for better alternatives in electronic devices. In comparison to PZT, group III nitrides such as aluminum nitride (AlN), are only weakly piezoelectric, but doping AlN with scandium (Sc) improves the piezoelectric response by nearly 500%. Relative to PZT, doped‐AlN piezoelectric materials are advantageous because they are far more compatible with complementary metal–oxide–semiconductor (CMOS) materials, and they maintain both piezoelectric and thermodynamic stability up to very high temperatures. Unfortunately, rare‐earth metals are notoriously expensive, and fabricating stable films with rare‐earth dopants is also challenging, limiting their use in industrial applications. In this work, ab initio calculations are combined with targeted fabrication and experimentation to identify alternative earth‐abundant dopants for AlN from the periodic table d‐block. Amongst the 23 elements screened, it is found that group IVB metals, titanium, zirconium, and hafnium induce large piezoelectric enhancements comparable to Sc. This improvement is traced to shifts in the atomic sublattice structure and changes in the local charge states. In demonstrating a highly accessible and affordable path for technological adaptation of AlN‐based piezoelectrics, this work provides the foundation for sustainable, next‐generation electronics.

Surface and bulk acoustic wave resonators based on aluminum nitride for bandpass filters

“…The increase of du/dε and elastic softening was also the origin of the d 33 enhancement in Cr x Al 1-x N and Yb x Al 1-x N. Yb-Yb pair interaction contributed to the elastic softening [75,133]. Numbers of TM x Al 1-x N configurations were determined to present higher piezoelectric performance than the pristine AlN [134]. Relationships between the type and distribution of TM and the d 33 of TM x Al 1-x N were also discussed [135].…”

Enhancing Manufacturability of SU-8 Piezoelectric Composite Films for Microsystem Applications

“…The measured properties are represented by d 33,f as the films remained on the Si substrate. The actual d 33 values of the films will be higher and can be calculated based on the mechanical properties of films [ 48 , 49 , 50 ]; however, the reported d 33 values in this paper refer to the measured d 33,f values.…”

Metal‐Organic Chemical Vapor Deposition of Aluminum Yttrium Nitride

“…LEDs [1] and high electron mobility transistors (HEMTs) [2][3][4][5][6] are among the best-known devices based on the so-called "classical" nitrides, which are the group 13 nitrides (formerly known as group IIIA nitrides). In the last decade, transition metals such as Nb, Er, Yb, La, Lu, Cr, W, Fe [7][8][9][10][11][12][13][14][15] and especially group 3 nitrides [16][17][18] have raised a strong interest in the scientific but also industrial community thanks to several features obtainable by alloying them in wide bandgap semiconductors, and especially scandium in AlN layers. [19] The presence of an element like Sc or Y with d orbitals and a large ionic radius causes relevant effects on the material properties of AlN.…”