Pixel Switching Research Articles

Single crystal silicon thin film transistors fabricatedat low process temperatureson glass substrates

Thin film transistors were fabricated in single crystal silicon films bonded to glass substrates. High electron mobilities were achieved, making integration of the driving circuitry and pixel switching elements on the same glass substrate possible and allowing improved display aperture ratios. These single crystal silicon TFTS are attractive for AMLCD applications.

A cascadable InGaAsP-InP optoelectronic smart pixel with low switching energy

We demonstrate for the first time a 1.3-/spl mu/m wavelength optoelectronic InGaAsP-InP smart pixel switching circuit using monolithically integrated p-i-n photodiodes and heterojunction bipolar transistors, along with surface-mounted folded-cavity surface-emitting lasers. The circuit functions as a cascadable optical switch with an on/off ratio of 6, and a maximum optical input/output differential gain of 6. At a bit rate of 100 Mb/s, a record low switching energy of 30 fJ was observed while maintaining circuit gain and cascadability. This switching energy is the lowest reported to date for an optoelectronic smart pixel. >

Fabrication of a Single Crystal Silicon Substrate for AM-LCD Using Vertical Etching of (110) Silicon

ABSTRACTIn this paper, feasibility of crystalline silicon (c-Si) substrate for transmissive active matrix liquid crystal displays (AM-LCDs) has been investigated. The transparent pixel areas of AM-LCD were formed by vertical etching of (110) silicon substrate using anisotropie etching property of aqueous KOH. Combining this vertical etching process with the conventional MOSFET fabrication process, the pixel switching devices, peripheral circuits and transparent apertures were successfully integrated on the same c-Si substrate. The pixel NMOS devices exhibit an electron mobility of about 600cm2/V-s, a subthreshold slope of 65mV/decade and ON/OFF current ratio of 9 decades at 5V drain voltage. And the gate delay time is 3.3ns at 10V power voltage, measured from a ring oscillator which has enhancement-load type NMOS inverters having the (W/L) iload- (W/L) driverer of 25μm/15μm - 50μm/10μm.

Design, fabrication, switching, and optical characteristics of new magneto-optic spatial light modulator

A new reflected mode magneto-optic spatial light modulator (R-MOSLM) has been developed for miniature optical correlators and computers. A factor of 4 improvement in pixel switching sensitivity, compared to the conventional transmission mode magneto-optic spatial light modulator, has been achieved by the use of narrower drive lines, and burying the conductor into the film. A factor of 3 higher resolution and a factor of 2 higher optical efficiency have also been achieved by the use of smaller pixels and narrower pixel gaps. The smaller pixels and improved switching sensitivity permit an order of magnitude reduction in optical path length and increase in frame rate, respectively. The progress that has been made in the design of the R-MOSLM, issues concerning its fabrication, a comparison by finite element analysis of field modeling to experimentally determined current requirements to drive individual lines, and some optical characteristics are discussed.

The effects of metal-n/sup +/ interface and space charge limited conduction on the performance of amorphous silicon thin-film transistors

We derive a contact current density expression that accounts for both the metal-n/sup +/ film interface resistance and the space charge limited conduction in amorphous silicon thin-film transistors. Our model demonstrates that the metal-n/sup +/ interface behavior dominates over space charge limited conduction for the a-Si:H film thicknesses used in pixel switching.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Optimization of an ultrafast OASLM using photoexcitations in organic thin films : the incoherent-to-coherent conversion efficiency of spectral concentration

Optically addressed spatial light modulators are characterized in terms of pixel density, exposure sensitivity and switching time. Third order nonlinear optical materials are attractive in order to improve on pixel density and switching speed. They are compared using appropriate figures of merit. The picosecond photochromism of some conjugated oligomers makes them prototype materials for thin film incoherent to coherent optical converters. Spectral concentration is identified as the key feature which permits spectrally large exposure sensitivities in single molecules. Molecular engineering rules of the spectral concentration are proposed. Conjugated oligomers of linear polycycles have the required structure in order to achieve 1 pJ/pixel exposure sensitivity in the MHz to GHz frequency range

A complexity analysis of smart pixel switching nodes for photonic extended generalized shuffle switching networks

The architectural tradeoffs found in the use of smart pixels for nodes within photonic switching interconnection networks are discussed. The particular networks of interest within the analysis are strictly nonblocking extended generalized shuffle (EGS) networks. Several performance metrics are defined for the analysis, and the effect of node size on these metrics is studied. Optimum node sizes are defined for each of the performance metrics and system-level limitations are identified.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Minicomputer interface for magneto-optic spatial light modulator

Digital optical data storage and processing are rapidly increasing in technological importance. The magneto-optic spatial light modulator (MOSLM) is a relatively low-cost, small pixel optical parallel input device that is capable of binary amplitude or binary phase modulation of each pixel. Thus, it is well matched to digital optical coherent storage and processing technology. However, potential problems associated with its use include: lack of a design for a general minicomputer interface, lack of interactive data-page file generation software, lack of ability to switch single pixels in some cases, lack of remote-from-computer operation capability, spurious pixel switching, and catastrophic failure due to thermal effects. The hardware and software components of a versatile minicomputer interface that has been successful in overcoming all of these problems are described. This interface allows easy data entry of entire data pages or single pixels and minimizes cross talk and noise developed over long cable lengths. In tests, the designed interface has produced highly stable operating characteristics.

Amorphous Silicon Alloy Punch-Through Diodes for Display Applications

AbstractThe current-voltage characteristics of amorphous silicon alloy n-π-n and p-i-p diodes have been investigated. These diodes show highly nonlinear conduction characteristics which are attributed to the punch-through effect. The dependence of the non-linearity on the thickness and doping of the intermediate active layer support this interpretation. An experimental 108 × 108 pixel liquid crystal display was built with punch-through diodes as pixel switches.

Fabrication of High Voltage Polysilicon TFT's on an Insulator

Using thin film transistors in active‐matrixed addressed large area displays has recently become important in display development. Specifically, a PLZT ceramic dot‐matrix display requires high voltage TFT pixel switching. To meet the need, a process has been developed utilizing polysilicon and temperatures less than 850°C, which yields MOSFET's capable of operating at voltages in excess of 50V with high ratios. High mobilities are obtained by fabricating n‐channel, accumulation‐mode devices in silicon deposited in the amorphous state and later annealed to the final polycrystalline condition.