Enhanced piezoelectric response of AlN via alloying of transitional metals, and influence of type and distribution of transition metals

TL;DR

This study investigates how alloying aluminum nitride (AlN) with various transition metals affects its piezoelectric response, revealing that specific metals and their distribution significantly enhance the material's piezoelectric properties.

Contribution

It is the first to analyze the influence of the type and distribution of transition metals on AlN's piezoelectric response, identifying key factors for performance improvement.

Findings

Most TM-alloyed AlN samples show higher d33 than pure AlN.

Mo alloying significantly enhances d33, up to 12.3 times that of pure AlN.

Distribution of Mo atoms, especially in Al sublayers, critically affects piezoelectric performance.

Abstract

Aluminum nitride (AlN) is an important piezoelectric material for a wide range of applications, many efforts are devoted to improving its piezoelectric response by alloying with transition metals (TMs). In this paper, the influence of the type and distribution of TM on the piezoelectric response is discussed for the first time. TM0.0625Al0.9375N with twenty-eight different TMs are investigated, and most show higher values of piezoelectric strain modulus d33 than that of AlN. This is because the TM introduces weaker TM-N bonds and locates closer to the centre of three neighbouring N atoms. The location of TM is determined to be significantly correlated with its group number. Alloys of TMxAl1-xN (TM=Sc, Cr, Sr, Mo, Ru and Rh) with varying x are further studied. On basis of the cost of the TMs and piezoelectric performances, the alloy with Mo is more effective in enhancing d33. A high d33 of 12.3 times that of pure AlN is realized in a metastable configuration of Mo0.167Al0.833N. The distribution of Mo plays a key role in the piezoelectric performance. A higher d33 is more likely to appear in MoxAl1-xN with more Al sublayers containing Mo atoms and with fewer dimers of Mo atoms along the z-axis.