Defect-induced negative differential resistance of GaN nanowires measured by conductive atomic force microscopy

Abstract

We report on negative differential resistance ͑NDR͒ from individual GaN nanowires prepared without catalysts by thermal chemical vapor deposition. Conductive atomic force microscopy was used to characterize the electron transport behavior and transmission electron microscopy was employed to characterize the microstructure of the GaN nanowires. The current-voltage curve exhibits two clear NDR regions in the forward bias. The defect assisted inelastic tunneling process resulting in the NDR behavior and the related mechanism for energy band diagram is proposed and discussed.

Current Imaging and Electromigration-Induced Splitting of GaN Nanowires As Revealed by Conductive Atomic Force Microscopy

“…The GaN NWs were synthesized by metal-catalyzed chemical vapor deposition (CVD) in a tube furnace. 11 Figure 1a shows that the as-synthesized NWs are 100Ϫ400 nm in width and several tens of micrometers in length. The typical NW cross sections are triangular or trapezoid in shape (inset of Figure 1a).…”

“…GaN nanowires (NWs) exhibit low lasing thresholds for the UV nanolasers, and their heterojunctions have been demonstrated to be high-efficient visible LEDs. Although GaN normally prefers to be in a wurtzite (WZ) crystal structure, WZ GaN NWs grown via a common vapor−liquid−solid (VLS) process often contain numerous stacking defects composed of metastable zinc blende (ZB) GaN phase regions, and bicrystals made of twinned GaN NWs were also reported. , These defects may influence the luminescence by introducing additional electronic states and/or may lead to a negative differential resistance due to acceptor-like defect levels . In this work, through current mapping of individual GaN NWs by C-AFM, we show that these defects can act as the electrical paths with localized high current densities.…”

A Review of Mechanical and Electromechanical Properties of Piezoelectric Nanowires

“…Thus, to obtain measurements that probe the effect of size and not the particular synthesis route, assessing the potential influence that defects have on the electromechanical and mechanical response, coupled with their direct identification in the tested nanowires, is imperative. Defects are known to affect, for example, mechanical,24 optical26 and electrical27 behavior of a material. The fact that defects play a role in mechanical behavior is widely accepted, although a quantification of their specific influence in the case of nanowires is still a subject of intense research (see section 3.2).…”

New Twin Structures in GaN Nanowires

“…25,26 According to the recent results, ordered twin domains in GaN nanowires have been observed to change the local band gap, acting as an inserted quantum well. 19 Planar defects, such as stacking faults and twin boundaries, are likely to introduce additional electronic states near the band edges 27,28 and influence the luminescence, electrical, and field emission properties of GaN nanowires. 19,24,27−29 Therefore, it is necessary to investigate the structures and reveal the planar defects, especially those unclear atomic configurations 29,33 in GaN nanowires, which are synthesized via a CVD process.…”