Evidence of Piezoelectric Potential and Screening Effect in Single Highly Doped ZnO:Ga and ZnO:Al Nanowires by Advanced Scanning Probe Microscopy

A complete study based on advanced atomic force microscopy electrical mode called scanning spreading resistance (SSRM) is carried out a series of samples zinc oxide (ZnO) nanowires grown by chemical bath deposition with different doping concentrations using gallium (Ga). The concentration free charge carriers determined through SSRM signal calibration specific molecular beam epitaxy-grown multilayer structure variation in each layer electrically active Ga ranges from 1 × 1017 to 7 1020 at./cm3. It was found that the changed every nanowire sample ratio precursor. increases 3 1018 at./cm3 non-intentionally doped 7.6 1019 precursor [Ga(NO3)3]/[Zn(NO3)2] more than 2%, which makes it possible gradually dope accurate regulation concentration. similar activity for aluminum (Al)-doped found. Piezoresponse (PFM) dual-frequency resonance tracking (DFRT) reveals stable piezoelectric highly presumably attributed increased surface trap density causing Fermi level pinning when ZnO are at high pH value favorable intentional doping. also shows degradation properties caused “screening effect,” directly correlates increase carrier nanowires. PFM DFRT eventually proposed as an original direct method analyzing single nanowire.