Characterizations of Ohmic and Schottky-behaving contacts of a single ZnO nanowire

Abstract

Current-voltage and Kelvin probe force microscopy (KPFM) measurements were performed on single ZnO nanowires. Measurements are shown to be strongly correlated with the contact behavior, either Ohmic or diode-like. The ZnO nanowires were obtained by metallo-organic chemical vapor deposition (MOCVD) and contacted using electronic-beam lithography. Depending on the contact geometry, good quality Ohmic contacts (linear I-V behavior) or non-linear (diode-like) contacts were obtained. Current-voltage and KPFM measurements on both types of contacted ZnO nanowires were performed in order to investigate their behavior. A clear correlation could be established between the I-V curve, the electrical potential profile along the device and the nanowire geometry. Some arguments supporting this behavior are given based on technological issues and on depletion region extension. This work will help to better understand the electrical behavior of Ohmic contacts on single ZnO nanowires, for future applications in nanoscale field-effect transistors and nano-photodetectors.

Direct observation of surface charge redistribution in active nanoscale conducting channels by Kelvin Probe Force Microscopy

“…Furthermore, the operational status of devices can be studied by in-situ local potential extraction e.g. surface plasmon field [21], potential fluctuation in crystal grains [12,22], junction of sollar cell under illumination [23], potential change in p-n junction under biasing [7,[24][25][26], nonlinear local potential drop due to Schottky contacts [27], the variation of doping or surface charge [28]. The local electrical potential is not only associated with the properties of materials or device themselves but also with the measurement environment [29][30][31], applied bias induced local charge trapping or injection [30,[32][33][34], and ion transportation [35].…”

Piezoelectricity and charge trapping in ZnO and Co-doped ZnO thin films

“…Indeed, KPFM is a well-established technique that has been used to measure the contact potential between two surfaces brought into close proximity with each other. [36][37][38][39] By doing this, we will be able to qualify the nature of the interface between the metal electrode (atomic force microscopy tip) and our samples as a Schottky barrier and we will investigate the phenomenon of charge storage in both ZnO and Co-doped ZnO. 40,41 II.…”

ZnO Nanowire Application in Chemoresistive Sensing: A Review

“…Single connection devices rely on the response of a single NW, deposited or aligned between two metal contacts. Ohmic contacts are mostly used to contact ZnO NW; however, it is also possible to make Schottky contacts (e.g., contacting with Pt) in order to obtain a rectifying character or conduction [ 35 ]. However, most of research is done with NW-NW junction type of contacts, which is used not only because of the ease of sensor manufacture, but also due to the ability to control the barrier height.…”