NOVELTY - An one-dimensional (1-D) or two-dimensional (2-D) nanostructure comprises a rough surface, and an optionally doped semiconductor, where the nanostructure is not a silicon nanowire prepared by immersing cleaned p-type (111)-oriented silicon substrates into an aqueous hydrofluoric acid/silver nitrate (HF/AgNO3) solution for 20 minutes at 50 degrees C. The nanostructure is an 1-D, such as nanowire (40), or 2-D nanostructure.    USE - As one-dimensional (1-D) or two-dimensional (2-D) nanostructure useful in device comprising thermoelectric power generator and thermoelectric cooler (claimed) for thermoelectric power generation or thermoelectric cooling, such as computer chip cooling.    ADVANTAGE - The one-dimensional and two-dimensional nanostructures provides synthesis of large-area arrays of rough silicon (Si) nanowires that have thermal conductivity (k) of 1 W-m-1K-1 and exhibit a large thermoelectric figure of merit (ZT) of 0.8. By incorporating phonon-scattering interfaces at various length scales, it is possible to impede thermal transport and improve ZT. By using the nanostructures for forming Si nanowires, the k of Si is reduced 100-fold in nanowires as compared to bulk at room temperature. Roughness at the nanowire surfaces efficiently scatters phonons and reduces k even further at lower temperatures. Although bulk Si is a poor thermoelectric material, by significantly reducing k without affecting other parameters, Si nanowire arrays show promise as high-performance and inexpensive thermoelectric materials for everyday applications.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) a device comprising at least one one-dimensional (1-D) or two-dimensional (2-D) nanostructures, each contacting a first electrode (10) and a second electrode (90);    (2) a method of creating an electric current involving providing the device, and increasing the temperature of the first electrode, such that an electric current is created that flows from the first electrode to the nanostructure, and through the nanostructure to the second electrode; and    (3) a method of decreasing the temperature at a locality involving providing the device, where an electric power is in communication with the second and third electrodes and the first electrode is at or near the locality, and flowing an electric current from the second electrode to the second nanostructures, through the second nanostructures to the first electrode, through the first electrode to the first nanostructures, through the first nanostructures to the third electrode; such that the temperature at the locality is decreased.    DESCRIPTION OF DRAWING(S) - The figures show schematic views of a device comprising the nanowire useful for creating an electric current, and electrical current that is created by use of the device.    First electrode (10)    Nanowire (40, 50)    First end of nanowires (41, 51)    Second end of nanowires (42, 52)    Second electrode (90)