Development of a Dual-Probe Scanning Tunneling Microscope for Investigating Nanoscale Materials and Devices

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9522221 Boland This award provides funds to develop a dual-probe scanning tunneling microscope (DP-STM) to investigate nanoscale material and device properties. DP-STM is essentially identical to conventional single probe STM except that it enables two independent STM probes to be positioned 10-100nm from each other. This capability will be achieved by the controlled growth of nanowhiskers on each STM probe. A method is described to reliably position the whiskered probes within the prescribed separation. In contrast to conventional STM which can only measure local static properties of materials, DP-STM opens up whole new areas of investigation, particularly in the area of non-local dynamical and relaxation phenomena. By selecting the locations of the STM probes it is possible to measure transport and surface band dispersion along any particular direction in the material. A variety of novel pump- probe experiments are also possible. For instance, it is possible to measure how charge injection at a particular location affects the electrostatic potential and density of states at some nearby location. The latter is particularly interesting since it amounts to a fundamental description of the local chemical reactivity. DP-STM also represents a potentially powerfully technique to probe the characteristics and performance of nanodevices. ***