Ferroelectricity and Piezoelectric Response of (Sc,Y)N/(Al,Ga,In)N Monolayer Alternating Stacked Structures by First‐Principles Calculations

Abstract

Group III‐nitrides with doping recently attract great interest because of their outstanding ferroelectric and piezoelectric properties. Herein, the spontaneous polarization and piezoelectricity of the wurtzite III‐nitrides (AN, A = Al, Ga, In) with the rare earth element (R = Sc, Y) doping (w‐R0.5A0.5N) are investigated by first‐principles calculations. The polar w‐R0.5A0.5N and nonpolar h‐R0.5A0.5N are stable, which is proved by the elastic constants and phonon band structures. The w‐Sc0.5In0.5N and w‐Y0.5In0.5N can be applied to the ferroelectric field owing to their very small ferroelectric switching barriers (0.149 eV for w‐Sc0.5In0.5N and 0.042 eV for w‐Y0.5In0.5N) with large ferroelectric polarization (1.088 C m−2 for w‐Sc0.5In0.5N and 0.937 C m−2 for w‐Y0.5In0.5N). Furthermore, the w‐Y0.5In0.5N has a large piezoelectric strain constant d33 (14.018 pC N−1) based on the elastic constant C33 softening and the increase of the piezoelectric constant e33, which is three times larger than that of w‐InN (4.191 pC N−1). It is found that the biaxial tensile strain of 2% along in‐place significantly enhances the d33 and e33, which increase to 35.572 pC N−1 and 2.669 C m−2 from 14.018 pC N−1 and 1.700 C m−2 of free w‐Y0.5In0.5N, respectively.

Dawn of nitride ferroelectric semiconductors: from materials to devices

“…In 2022, Yazawa et al suggested that the strain sensitivity of switching barrier is one order of magnitude larger than that of the spontaneous polarization in wurtzite nitride ferroelectrics (figures 11(d) and (e)) [141]. Except for random Sc-III-N alloys, ferroelectric polarization switching properties in ScN/III-N superlattice has been also predicted by Noor-A-Alam et al [142], Sun et al [128], and Jiang et al [143] recently.…”

“…Such an enhancement in ScInN, however, has not been reported yet. Recent experiments and calculations also showed that BAlN and yttrium (Y) alloyed III-nitrides could be ferroelectric [114,128]. Since all ferroelectrics are piezoelectric, it would be advantageous to explore the piezoelectric response limit in those emerging materials [129][130][131].…”

“…Therefore, they suggested that YInN, beyond ScAlN, as a promising piezoelectric material [129]. Very recently, Sun et al predicted a switching barrier as low as 0.042 eV for Y 0.5 In 0.5 N, corresponding to a coercive field of 1.61 MV cm −1 , which is significantly lower than that of Sc 0.5 In 0.5 N and Sc 0.5 Al 0.5 N [128]. It indicates that the wurtzite YInN is another promising ferroelectric material.…”

Emerging ferroelectric materials ScAlN: applications and prospects in memristors

“…16,17 It should be pointed out that ScAlN is compatible with CMOS technology even in harsh environments. [18][19][20]…”