TECHNOLOGY FOCUS - ELECTRONICS - Preferred Components: The memory system is a memristor.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: Substrate contains silicon, indium tin oxide, fluorine-doped tin oxide, glass, polymer, metal foils, and/or flexible and/or transparent material which conducts electricity or can be coated with thin metal layer to conduct electricity, preferably silicon. Carbon nanostructure-oxide-metal vertical diode array contains carbon nanofibers, nanohorns, or nanocones coated with dielectric layer, and the tips of the carbon nanofibers, nanohorns, or nanocones are coated with metallic coating. Dielectric layer is doped to reversibly or irreversibly alter the electron density of the dielectric layer. Dielectric layer is doped with nitrogen, boron, oxygen, hydrogen, and/or hydroxyls. Dielectric layer is aluminum oxide (Al2O3), aluminum(II) oxide (AlO), zirconium dioxide (ZrO2), titanium dioxide (TiO2), zinc oxide (ZnO), tin dioxide (SiO2), magnesium oxide (MgO), niobium pentoxide (Nb2O5), cobalt(II) oxide (CoO), nickel(II) oxide (NiO), tantalum pentoxide (Ta2O5), hafnium(IV) oxide (HfO2), polymeric dielectrics, organic surface modifiers or molecules, and/or ionic liquids. Metallic coating contains low work functional metals consisting of Al, calcium (Ca), magnesium:silver (Mg:Ag), lithium fluoride:Al (LiF:Al), Ti, indium (In), tantalum (Ta), Hf, and/or Zr, preferably Al and Ca. Metallic coating contains high work functional metals/materials consisting of platinum (Pt), gold (Au), tungsten (W), Co, Ni, palladium (Pd), iridium (Ir), osmium (Os), and/or conducting polymers, preferably Pt and Au. The nanostructures contain carbon nanotubes. The device contains a support layer consisting of Ti, Ni, Pt, or Au. The structure contains catalyst layer consisting of Al, iron (Fe), Ni, Co, and/or other transition metals. The nanostructures are open-ended, and the metallic coating is in contact with multiple nanostructure walls or surfaces. The nanostructres are open-ended, and the oxide coating is in contact with multiple nanostructure walls or surfaces. Preferred Parameters: Thickness of dielectric layer is 0.5-15 nm, preferably 2-4 nm. Average height of carbon nanotubes is 0.5-50 mu m. Average height of carbon nanotubes is matched to the wavelength of the electromagnetic energy that is coupled to the device. Wavelength range in the solar spectrum is 300-2500 nm, wavelength range in the infrared portion of the solar spectrum is 1100-2500 nm, or wavelength range is 740-1000 nm, 1000-3000 nm, 3000-5000 nm, 8000-14000 nm, or 14000-50000 nm. Average height of the carbon nanotubes is an integer multiple of the wavelength of the electromagnetic energy that is coupled to the device. Diameter of the nanotubes is 5-40 nm, preferably 7-8 nm. Density of the nanotubes is 108-1012 CNTs/cm2, preferably 1010 CNTs/cm2.27. The device exhibits a rectification ratio of 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, or 60. The current density of the device is greater than or equal to 1 mA/cm2 at 2 V applied bias. The current density is greater than or equal to 100 nA/cm2 in open circuit when illuminated by electromagnetic energy at solar wavelengths. The turn-on voltage is less than or equal to 1 V, preferably less than or equal to 0.3 V. The rectification ratio, current density, and energy conversion efficiency change is less than or equal to 2% at 5-77 degrees C. The rectification ratio, current density, and energy conversion efficiency decrease is by less than or equal to 10, 9, 8, 7, 6, or 5% at 5-400 degrees C or 2-300 degrees K.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The high work functional material is poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS).