\NER: Coaxial Tip Piezoresistive Cantilever Probes for High-Resolution Scanning Gate Microscopy

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Objective:The goal of this research program is to design, fabricate and characterize novel probes for high-resolution scanning gate microscopy, a technique providing information on electron distribution and transport. Probes that can produce a highly-localized potential perturbation are needed to apply scanning gate microscopy to semiconductor nanostructures. The proposed probes consist of cantilevers with integrated coaxial tips to generate a confined dipolar electric field at the underlying sample. Deflection of the cantilever resulting from tip-surface interactions will be detected by modulation of a piezoresistor located at the root. Initially, the probe will be used to map the probability densities of electrons in quantum dots and other semiconductor nanostructures, which to-date is a highly-desirable but unrealized goal. Intellectual Merit:The intellectual merit includes fundamental understanding of electron organization in semiconductor nanostructures, explaining properties of these low-dimensional systems, and designing novel devices (spintronic, single-electron, etc.) exploiting these properties. Beyond scanning gate microscopy, applications include the investigation of biological specimens, failure analysis of integrated circuits, and the study of noise in semiconductor devices. The coaxial tip may also improve the resolution and contrast of scanning electrochemical microscopy and scanning near-field microscopy.Broader Impacts:The resulting knowledge will have broad social, economic, and educational impact. Improved understanding of cellular voltage-gated ion channels may lead to more effective drugs while greater insight into quantum dots may yield higher-performance replacements for transistors. Results will be disseminated through educational outreach programs. By addressing the broad problem of generating and detecting localized electromagnetic fields, the probes will influence research throughout the basic sciences and engineering.