Piezoresponse force microscopy (PFM) characterization of GaN nanowires grown by Plasma assisted Molecular beam epitaxy (PA-MBE)

Piezoelectricity in non-nitride III–V nanowires: Challenges and opportunities

“…Furthermore, both these studies indicate the piezoelectric coefficients at the 10-100 nm scale are similar to those theoretically predicted. This stands in some contrast to the results obtained for GaN NWs, where the axial piezoelectric strain coefficient (d33) was found to be 3-6 times higher than reported for bulk (8,90). Minary-Jolandan et al further reported a similar increase in the two other piezoelectric coefficients (8).…”

“…Minary-Jolandan et al further reported a similar increase in the two other piezoelectric coefficients (8). Although we are unaware of a study directly comparing NWs and bulk material, Tiwary et al went on to perform such finite element simulations (90). Their results indicate that the inherent softening of the NW compared to thin films (reduced mechanical constraints) might be behind the increased electromechanical response.…”

Toward Quantitative Measurements of Piezoelectricity in III-N Semiconductor Nanowires

“…, ZnO and GaN) have gained rising attention for mechanical energy scavenging applications after the report of ZnO nanowire-nanogenerators and self-powered nanosystems. , Improved electromechanical conversion efficiency was expected in ultrasmall nanowires due to the enhanced piezoelectricity theoretically predicted in ZnO and GaN nanowires with a diameter smaller than 2.4 nm . This giant piezoelectricity was experimentally deduced from piezoresponse force microscopy (PFM) signals of GaN single nanowires with a diameter of 60 nm, suggesting the piezoelectric coefficient up to six times the value of their bulk counterpart. , The PFM measurements on ZnO and GaN nanobelts , as well as GaN nanowires also indicated their enhanced piezoelectricity. On the contrary, the piezoelectric constant of ZnO nanorods interpreted from the PFM signals was close to that of bulk values …”

“…These artifacts lead to incorrect determination of piezoelectric coefficients and material polarities. For example, the higher-than-bulk piezoelectric coefficients observed in nanowires and nanobelts − might be merely caused by the artifacts.…”

Piezoelectric Semiconducting Nanowires

“…Most PFM work revolved around characterization of relatively thick, vertical, NWs -predominantly ZnO and GaN [63,35,64,65]. Scrymgeour and Hsu have correlated PFM and conductive AFM (c-AFM) measurements of ZnO nanorods (Figure 10).…”