Electrical characterization of Al/AlOx/molecule/Ti/Al devices

Models of charge transport and transfer in molecular switch tunnel junctions of bistable catenanes and rotaxanes

“…Switching is observed at higher applied voltages (±3 V), the switching is not metastable, and the ON:OFF current ratios can reach to 10,000:1. More importantly, the switching is independent [26] of the nature of the molecule present -rotaxanes or their non-switchable dumbbells, eicosanoic acid, 'fast blue' or chlorophyll-B, all display a device hysteresis and the data can be rationalized from a model based on trapped charges. This result suggests that devices built around bimetallic electrode systems, either the Pt/molecule/Ti/Al [49,50] or the Al/AlO x / molecule/Ti/Al [26] constitution, do not need bistable molecules to generate switching hysteresis.…”

“…More importantly, the switching is independent [26] of the nature of the molecule present -rotaxanes or their non-switchable dumbbells, eicosanoic acid, 'fast blue' or chlorophyll-B, all display a device hysteresis and the data can be rationalized from a model based on trapped charges. This result suggests that devices built around bimetallic electrode systems, either the Pt/molecule/Ti/Al [49,50] or the Al/AlO x / molecule/Ti/Al [26] constitution, do not need bistable molecules to generate switching hysteresis. This result underlines the importance of considering: (1) the relevant control studies that will distinguish molecular effects from possible molecule-independent ones and (2) the device constitutions and electrode materials that will allow the subtleties of a molecule's character to emerge [48].…”

“…One of the unifying themes is the control provided by the increasing modularity of chemical synthesis over the properties of the resulting devices [9]. A number of molecular paradigms are being explored presently: they include molecular rectifiers [10][11][12], molecular wires [13][14][15], molecular charge storage devices [16,17] and single-molecule studies [18][19][20][21], amongst others [22][23][24][25][26][27]. Common to all of these systems is that the molecular signature is expected by design to arise from charge transfer to/from (hopping) or across (tunneling) only one form of the molecule [28].…”

The Characterization of Silicon-Based Molecular Devices

“…Additionally, there is evidence that many of the materials used in molecular electronic devices chemically react with and/or migrate through the molecular monolayer, resulting in electrical device behavior that is dominated by artifacts, rather than the electrical behavior of the organic molecules. [11][12][13] Thus, it is imperative that methodologies are established to not only determine the electrical characteristics of integratable silicon-based devices, but to test that the device and substrate materials do not chemically react or migrate and disrupt the integrity of the molecular monolayer.…”

The Art of Catching and Probing Single Molecules

“…Even though a large variety of approaches have been used to create molecular junctions (5,123), there are currently only a few examples of unambiguous charge transport studies in literature (124)(125)(126)(127). A majority of the large area devices created and investigated are based on self-assembled monolayers (SAMs) immobilised between two macroscopic electrodes (15,(127)(128)(129)(130). However, due to the macroscopic nature of the metal-monolayer contacts, the current-voltage (I-V) data obtained always presents an average of the charge transport events that occur across the array of contacted molecules.…”