Access to residual carrier concentration in ZnO nanowires by calibrated scanning spreading resistance microscopy

Abstract

Scanning spreading resistance microscopy (SSRM) was performed on non-intentionally doped (nid) ZnO nanowires (NWs) grown by metal-organic chemical vapor deposition in order to measure their residual carrier concentration. For this purpose, an SSRM calibration profile has been developed on homoepitaxial ZnO:Ga multilayer staircase structures grown by molecular beam epitaxy. The Ga density measured by SIMS varies in the 1.7 × 1017 cm−3 to 3 × 1020 cm−3 range. From measurements on such Ga doped multi-layers, a monotonic decrease in SSRM resistance with increasing Ga density was established, indicating SSRM being a well-adapted technique for two dimensional dopant/carrier profiling on ZnO at nanoscale. Finally, relevant SSRM signal contrasts were detected on nid ZnO NWs, and the residual carrier concentration is estimated in the 1–3 × 1018 cm−3 range, in agreement with the result from four-probe measurements.

Dimensional Roadmap for Maximizing the Piezoelectrical Response of ZnO Nanowire-Based Transducers: Impact of Growth Method

“…Overall, it is well-known that ZnO NWs exhibit a high electrical conductivity and thus a high doping level, regardless of the growth method involved [ 28 ]. However, charge carrier density values spread over several decades from 10 17 cm −3 to 10 20 cm −3 [ 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 ]. The main reason is related to a large incorporation of residual impurities (i.e., Al, Ga, In, etc.)…”

Recent Advances of ZnO Based Nanowires and Nanorods Devices

“…The study's results also showed that SSRM can be well adapted for the dopant/carrier profiling in ZnO nanostructure [47]. Figure 2 shows the scan electron microscopy (SEM) image of the as-grown ZnO nanowires [47]. The synthesize of the ZnO nanowires using chemical vapor deposition system at 1000°C temperature were reported by Yadav et al [48].…”

“…The study's results showed that the residual carrier concentrations of ZnO nanowires were found to be between 10 18 and 3 x 10 18 cm -3 . The study's results also showed that SSRM can be well adapted for the dopant/carrier profiling in ZnO nanostructure [47]. Figure 2 shows the scan electron microscopy (SEM) image of the as-grown ZnO nanowires [47].…”

“…The Ga density was measured by secondary ion mass spectroscopy (SIMS) varies in the 1.7 x 10 17 cm -3 to 3 x 10 20 cm -3 range. From the measurements on Ga doped multi-layers, a monotonic decrease in SSRM resistance with increasing Ga density was established, indicating SSRM being a well adapted technique for two dimensional dopant/carrier profiling on ZnO at nanoscale [47]. The study's results showed that the residual carrier concentrations of ZnO nanowires were found to be between 10 18 and 3 x 10 18 cm -3 .…”

“…The measurements of the residual carrier concentration on non-intentionally doped ZnO nanowires using the scanning spreading resistance microscopy (SSRM) was reported by Wang et al [47]. For this purpose, an SSRM calibration profile was developed on homoepitaxial ZnO:Ga multilayer staircase structures grown by molecular beam epitaxy (MBE) [47]. The Ga density was measured by secondary ion mass spectroscopy (SIMS) varies in the 1.7 x 10 17 cm -3 to 3 x 10 20 cm -3 range.…”