Thomas Novet

Optically coded nanocrystal taggants and optical frequency IDs

A series of nanocrystal and nanocrystal quantum dot taggant technologies were developed for covertly tagging and tracking objects of interest. Homogeneous and heterogeneous nanocrystal taggant designs were developed and optimized for ultraviolet through infrared emissions, utilizing either Dexter energy transfer or Förster resonant energy transfer (FRET) between specific absorbing and emitting functionalities. The conversion efficiency, target-specific identification, and adhesion properties of the taggants were engineered by means of various surface ligand chemistries. The ability to engineer poly-functional ligands was shown effective in the detection of a biological agent simulant, detected through a NC photoluminescence that is altered in the presence of the agent of interest; the technique has broad potential applicability to chemical, biological, and explosive (CBE) agent detection. The NC photoluminescence can be detected by a remote LIDAR system; the performance of a taggant system has been modeled and subsequently verified in a series of controlled field tests. LIDAR detection of visible-emitting taggants was shown to exceed 2.8 km in calibrated field tests, and from these field data and calibrated laboratory measurements we predict >5 km range in the covert shortwavelength infrared (SWIR) spectral region.

Polysilicon metal-insulator-semiconductor electron emitter

The flat metal-insulator-semiconductor (MIS) electron emitter is a simple design, allowing easy manufacture. The emitters are relatively insensitive to environment, allowing them to operate in poorer vacuum conditions than are necessary for oxide thermionic or microtip field emitters. In most literature reports, MIS and metal-insulator-metal devices are limited in emission current ( 400pores∕μm2 through which electrons a...

Novel flat MIS electron emitter

The flat metal-insulator-semiconductor (MIS) electron emitter is a simple design allowing easy manufacture, and is relatively insensitive to environment conditions making operation possible in poor vacuum conditions. A stack of 5000 /spl Aring/ polysilicon/150 /spl Aring/ silicon oxide/50 /spl Aring/ gold deposited on n++ doped silicon showed the best performance. We have observed emission current densities as high as 2-10 A/cm/sup 2/ at efficiencies from 3-10%. The polysilicon serves a dual role. Bumps on the poly surface act as field-enhanced emission sites while the bulk of the film behaves as a ballast resistor that prevents run away emission from any one emission site. The thin gold layer self-assembles into a nano-mesh with >100 pores//spl mu/m/sup 2/ through which electrons escape. Emission theory, including energy distribution and angular divergence of the emitted beams, are discussed.