Nicholas E. Schlotter

Surface-enhanced Raman scattering (SERS) has enabled the detection of pathogens and disease markers at extremely low levels. This review examines the potential impact of SERS in addressing unmet needs in pathogen diagnostics both in a traditional clinical setting and in the point of care (POC) arena. It begins by describing the strengths and weaknesses of today's diagnostics technologies in order to set a contextual stage for an overview which highlights a few of the many recent developments using SERS in biodefense, human and animal health, and monitoring food and water safety. These sections are followed by discussions of the challenges for the translation of these developments to POC settings, including the performance attributes and metrics for quantification of analytical and clinical figures of merit (e.g., limit of detection and clinical accuracy), and the pathways for large-scale test validation and the build-out of instrumentation and tests kits for POC deployment.

A new source of cadmium diffusion in In_0.53Ga_0.47As has been developed. Langmuir–Blodgett (LB) deposited monolayers of cadmium arachidate have been used as a source of cadmium. The LB film has been characterized by grazing incidence infrared spectroscopy and Auger electron spectroscopy. Acceptor profiles obtained by differential Hall technique are presented. Highly doped (N_A =2×10¹⁹ cm⁻³) shallow (x_j ≊0.1–0.4 μm), p⁺‐n junctions are obtained. Mesa‐type p‐i‐n diodes with 125 μm diameter, ideality factor =1.3, I_dark =5 nA at 20 V reverse bias, and V_breakdown =30 V have been fabricated.

We report the fabrication of single‐mode channel waveguides in spun films of polydiacetylenes using an inverted rib design. These robust guides consist of a planar layer of the polydiacetylene spun on a glass substrate in which high‐index channels have been defined by ion exchange. Models of such guides show that most of the optical field of the guided wave is confined to the polymer layer, with the high‐index glass channels providing lateral confinement. End‐fire coupling of 1.06, 1.15, 1.32, and 1.55 μm light into the composite guides resulted in single‐mode guiding with the light confined to the polymer layer. This approach to waveguide formation should be applicable to a wide range of polymeric materials.

A technique is described for fabricating high-speed metal-insulator-semiconductor-insulator-metal (MISIM) photodetectors for high-speed fiber-optic systems. These devices make use of a Langmuir-Blodgett film enhanced Schottky barrier to achieve broadband linear response to 13 GHz at low bias voltage (5 V) with approximately 0.9 A/W external responsivity, 15 V breakdown voltage, and approximately 2 mu A dark current. A gain of about 2 and a 5% tail in the temporal response are analyzed. The needed bias and the device processing are compatible with those for integrated receivers.