In this work, tunable MEMS capacitors are realized using a vertically grown carbon nanotube array. The vertical CNT array forms an effective CNT membrane, which can be electrostatically actuated like the conventional metal plates used in MEMS capacitors. The CNT membrane is grown on titanium nitride metal lines, with a Al/Fe bi-layer as buffer layer and catalyst material respectively, using chemical vapor deposition process. Two different anchor configurations are investigated. A maximum capacitance of 400 fF and maximum tunability of 5.8% is extracted from the S-parameter measurements. Using the tunable MEMS vertical array capacitor a voltage controlled oscillator (VCO) is demonstrated showing promise for integrating CNTs for communications applications.
Current tendencies in infrared arrays are to decrease the pitch and increase the number of detectors without degrading the electro-optical performances. It is therefore necessary to maximize the charge-handling capacity in the pixel. In this paper, a new architecture particularly-well suited to this kind of application is described.-A brief review of classical readout circuits is given. The advantages and drawbacks of these architectures are emphasized.-The new architecture is discussed in detail, compared to existing ones and the performance ofthe new readout circuit evaluated.Results measured on IRCMOS designed with the new architecture are presented.
The performances of a new CdTe based X-ray detector devoted to digital radiography are presented. The detectors consist of a 6 cm2 CdTe 2D-array connected to CMOS readout circuit by indium bumps. The final image has 400x600 pixels with a 50 micron pitch.This solid-state detector presents the advantages of direct (X-rays into charges) conversion, i.e. high stopping power with high spatial resolution and a significantly higher signal than commercially available scintillator/photodetector systems.The experimental results show excellent linearity, spatial resolution and detective quantum efficiency. The MTF was measured by the angled-slit method (Fourier transform of the pre-sampled Line Spread Function) : 20 to 30 % at 10 lp/mm depending on the incident X-ray energy. The measured DQE (at zero frequency) is about 0.8 at 40 KeV and 100 Gray dose.Our simulation (energy deposition by ITS Monte Carlo code) shows that these experimental results don't reach the theoretical limit. Further improvements are in progress.The first industrial application will be dental radiography (40 KeV mean energy) due to the small size and the excellent performances. We also tested the detector with X-rays from 20 KeV to 1.25 MeV. Of course the CdTe thickness should then be adapted to the incident X-ray energy.
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