Theoretical evidence of piezoelectric constant enhancement of M-doped AlN (M = Sc, Er)

The piezoelectric properties of Sc-or Er-doped wurtzite AlN at different dopant concentrations were investigated using the first-principles calculations by analyzing the lattice distortion and the bonding type. It is found that when x = 0.5, Sc-or Er-doped AlN presents the highest piezoelectric constants in several dopant concentrations, namely, 25.50 pC/N for Sc0.5Al0.5N and 9.34 pC/N for Er0.5Al0.5N. By calculating the coordinate difference between positive and negative charge centers, it is confirmed that the enhancement of piezoelectric constant for M-doped AlN (M = Sc, Er) is related to the long polarization length. Meanwhile, Mulliken population analysis proves that the improved ionicity of Al-N bond after doping is another reason for the enhancement of piezo-electric constant. This work provides a theoretical basis for further improving the piezoelectric properties of AlN and its application in the high-frequency devices.

Automated summary

The piezoelectric properties of Sc-or Er-doped wurtzite AlN at different dopant concentrations were investigated using first-principles calculations. It was found that Sc0.5Al0.5N and Er0.5Al0.5N exhibited the highest piezoelectric constants at a dopant concentration of 0.5, with values of 25.50 pC/N and 9.34 pC/N, respectively. The enhancement of piezoelectric constant was attributed to the long polarization length and improved ionicity of Al-N bond after doping.