19 research outputs found
Amorphous and Polycrystalline Photoconductors for Direct Conversion Flat Panel X-Ray Image Sensors
In the last ten to fifteen years there has been much research in using amorphous and polycrystalline semiconductors as x-ray photoconductors in various x-ray image sensor applications, most notably in flat panel x-ray imagers (FPXIs). We first outline the essential requirements for an ideal large area photoconductor for use in a FPXI, and discuss how some of the current amorphous and polycrystalline semiconductors fulfill these requirements. At present, only stabilized amorphous selenium (doped and alloyed a-Se) has been commercialized, and FPXIs based on a-Se are particularly suitable for mammography, operating at the ideal limit of high detective quantum efficiency (DQE). Further, these FPXIs can also be used in real-time, and have already been used in such applications as tomosynthesis. We discuss some of the important attributes of amorphous and polycrystalline x-ray photoconductors such as their large area deposition ability, charge collection efficiency, x-ray sensitivity, DQE, modulation transfer function (MTF) and the importance of the dark current. We show the importance of charge trapping in limiting not only the sensitivity but also the resolution of these detectors. Limitations on the maximum acceptable dark current and the corresponding charge collection efficiency jointly impose a practical constraint that many photoconductors fail to satisfy. We discuss the case of a-Se in which the dark current was brought down by three orders of magnitude by the use of special blocking layers to satisfy the dark current constraint. There are also a number of polycrystalline photoconductors, HgI2 and PbO being good examples, that show potential for commercialization in the same way that multilayer stabilized a-Se x-ray photoconductors were developed for commercial applications. We highlight the unique nature of avalanche multiplication in a-Se and how it has led to the development of the commercial HARP video-tube. An all solid state version of the HARP has been recently demonstrated with excellent avalanche gains; the latter is expected to lead to a number of novel imaging device applications that would be quantum noise limited. While passive pixel sensors use one TFT (thin film transistor) as a switch at the pixel, active pixel sensors (APSs) have two or more transistors and provide gain at the pixel level. The advantages of APS based x-ray imagers are also discussed with examples
A two-dimensional model for interface coupling in triple-gate transistors
International audienc
High-temperature characterization of advanced strained nMuGFETs
International audienceDC measurements at high temperature of n-channel triple-gate transistors with 25 nm fin-width and 65 nm fin-height, high-k dielectric and metal gate for strained and unstrained substrates are investigated. The variations of the main transistor parameters with temperature are analyzed from room temperature up to 200°C
High-temperature performance of state-of-the-art triple-gate transistors
International audienc
Gate voltage and geometry dependence of the series resistance and of the carrier mobility in FinFET devices
status: publishe
Impact of strain and source/drain engineering on the low frequency noise behaviour in n-channel tri-gate FinFETs
International audienc
Low-power voltage-controlled oscillators in 90-nm CMOS using high-quality thin-film postprocessed inductors
Wafer-level packaging (WLP) technology offers novel opportunities for the realization of high-quality on-chip passives needed in RF front-ends. This paper demonstrates a thin-film WLP technology on top of a 90-nm RF CMOS process with one 15-GHz and two low-power 5-GHz voltage-controlled oscillators (VCOs) using a high-quality WLP or above-IC inductor. The 5-GHz VCOs have a power consumption of 0.33 mW and a phase noise of - 115 dBc/Hz and -111 dBc/Hz; at 1-MHz offset, respectively, and the 15-GHz VCO has a phase noise of -105 dBc/Hz at 1-MHz offset with a power consumption of 2.76 mW
DC and RF characteristics of a 60 nm FinFET for a wide temperature range
DC and RF characteristics of n-type FinFET transistor over a wide temperature range, from 77 to 473K, are presented for the first time. We experimentally demonstrate that the impact of temperature on the main analog and RF factors of merit of FinFETs is similar to what it can be observed for classical deep submicron single gate MOSFETs