Thomas Starke

High sensitivity NO2 sensors for environmental monitoring produced using laser ablated nanocrystalline metal oxides

This paper presents results from a study of gas sensors produced using laser ablated nanocrystalline metal oxides. The devices have been tested for their potential use as NO2 detectors with particular emphasis on their potential cross sensitivity to NO. Subsequently, these SnO2 devices are compared with the gas sensing capabilities of other sensors made from In2O3 and WO3 prepared via a similar route. The investigation focussed on studying these sensors at low concentration levels with a view to environmental monitoring applications. Very high sensitivities to low NO2 levels together with fast response times have been observed for both SnO2 and In2O3 materials.

LASER-ABLATED NANOCRYSTALLINE SNO2 MATERIAL FOR LOW-LEVEL CO DETECTION

Abstract This paper presents results from a study, which shows that laser-ablated nanocrystalline SnO 2 can be used for low-level CO detection such as in environmental monitoring applications. Laser ablation has the advantage of producing nanocrystalline material free of surface contamination that can be detrimental for the detection capabilities of the sensors. Initially, the performance of this material was evaluated with respect to doping agents, operating temperature and film thickness. Subsequently, the sensors were operated in a pulsed-temperature mode. The sensors produced show superior sensitivities to CO concentrations at single-figure ppm levels at high resolution and with very low cross sensitivity to common interference gases.

High sensitivity ozone sensors for environmental monitoring produced using laser ablated nanocrystalline metal oxides

A series of gas sensors produced using the laser ablated nanocrystalline metal oxides. SnO/sub 2/, In/sub 2/O/sub 3/, and WO/sub 3/ have been studied. Devices were tested with a view to their potential use as ozone detectors. Initially, fabrication procedures and compositions were optimized. The investigation then focused on parameters important for environmental monitoring applications including sensitivity, selectivity, and response time. High sensitivities to ppb ozone levels were observed particularly in the case of devices produced using SnO/sub 2/ and In/sub 2/O/sub 3/. Good selectivity was also observed for all optimized materials together with fast response times. These latter characteristics were particularly good for devices produced using WO/sub 3/.

Highly effective junction isolation structures for PICs based on standard CMOS Process

This paper presents novel and highly effective junction isolation structures for power integrated circuits. The negative feedback-activated junction isolation is presented and it is proven to be very effective in blocking substrate current from reaching the logic circuitry (orders of magnitude more effective than standard junction isolation techniques). Additionally, in an attempt to further improve the blocking capabilities of junction isolations the use of multiple or combined structures is investigated whilst keeping the surface area used for isolation device in the same range as for the single structures. All isolation structures presented here are based on a 0.6-/spl mu/m CMOS technology.

Reduced response times using adsorption kinetics and pulsed-mode operation for the detection of oxides of nitrogen with nanocrystalline SnO/sub 2/ sensors

The work presented in this paper investigates the use of pulsed temperature operation of nanocrystalline SnO/sub 2/ sensors for detecting oxides of nitrogen. Pulsed-mode operation was employed to expand the detection range of these sensors while maintaining high sensitivity at low concentrations. In an attempt to reduce the response times of these devices, adsorption kinetics were applied to the response data. Gas concentrations as low as 10 ppb could be rapidly determined without waiting for a steady-state response to be achieved. The sensors also showed a strong response to ppb levels of NO even at low pulsing temperatures.

Active junction isolation for smart power integrated circuits

A structure for the isolation of power transistors from (CMOS) control circuitry used in smart power integrated circuits is proposed. This negative feedback activated junction isolation is compatible with standard CMOS technology.

Advanced junction isolation structures for Power Integrated Circuit technology

This paper describes recent experimental work carried on the optimisation of junction isolation structures for use in Power Integrated Circuits. Isolation is required to collect minority carriers injected into the substrate before the can reach the low voltage control circuitry. The most effect form of isolation found in this paper combines A number of techniques (SJI & MAAP) to reduce the injected current by3 orders of magnitude compared with the standard junction isolation techniques.

Novel 2-D RESURF LDMOSFET in 0.6 /spl mu/m CMOS technology for power ICs

A 0.6 /spl mu/m CMOS process was adapted to incorporate LDMOS transistors for Power Integrated Circuit Applications. The design was realised by adding only three additional ion implants process steps and one extra masking process step providing a cost effective approach. The design was optimised prior to manufacture by the Avanti TCAD simulation tool. Physical results show good agreement with the simulated device and display 2-D RESURF action.

New LDMOS transistor based on 0.6 /spl mu/ CMOS technology for power IC applications

New LDMOSFET device based on 0.6 microns CMOS technology (X-Fab Plymouth, UK) is presented in this paper. The process is based on p-(substrate)/p-(epi) layers, layer thicknesses and dopings being standard for this type of technology. The optimised device has a 75 V breakdown voltage.