Vincent D. Cannella

Active-matrix organic light-emitting displays employing two thin-film-transistor a-Si:H pixels on flexible stainless-steel foil

— An active-matrix organic light-emitting diode (AMOLED) display driven by hydrogenated amorphous-silicon thin-film transistors (a-Si:H TFTs) on flexible, stainless-steel foil was demonstrated. The 2-TFT voltage-programmed pixel circuits were fabricated using a standard a-Si:H process at maximum temperature of 280°C in a bottom-gate staggered source-drain geometry. The 70-ppi monochrome display consists of (48 × 4) × 48 subpixels of 92 ×369 μm each, with an aperture ratio of 48%. The a-Si:H TFT pixel circuits drive top-emitting green electrophosphorescent OLEDs to a peak luminance of 2000 cd/m2.

Full Color Display With Amorphous Silicon Pin Diodes For High Performance Applications

This paper presents the recent developments in our Active Matrix Liquid Crystal Displays for military, avionic and automotive applications. Data is presented for PIN diode driven active matrix liquid crystal display, with full color and high resolution (164 lines per inch). Optimization of color coordinates versus transmission has led us to better overall display performance. The contrast ratios were measured for various viewing angles (+/-60H and +45,-15 V) at different temperatures (-54 C to +85 C). The display shows good high ambient contrast ratio both by theoretical model and experimentally. The discrimination index model is used together with measurements to get the index for different high ambient light levels.

Performance Of Full Color Active-Matrix-Lcd In The Cockpit Environment

The performance of a display designed for cockpit applications is discussed. This PIN diode driven active matrix liquid crystal display is capable of operating over a wide temperature range (-40 C to +85 C). It has wide viewing angles (+/-50 H and +15/-30 V), grey scale, and full colors. The resolution is 164 lines per inch. The performance of the display over the whole temperature range is presented. The model of the discrimination index for testing the combined contrast-ratios and colors discrimination was applied for this display. Measurements at different ambient-light levels are presented, both for diffused and specular reflections. Contrast ratios, reflections, and color measurements at different viewing angles are used for discrimination index calculations. The high performance of the display with special surface treatment (front and back) in the cockpit environment is discussed based on those measurements and calculations.

8"*8" full color cockpit display

The operation of active matrix liquid crystal displays (AMLCDs), the preferred flat-panel displays for avionic and aerospace applications, is explained. An 8-in.*8-in. full-color AMLCD designed for a military aircraft is described, as well as the principles of the p-i-n diode switch on which its design is based. The performance characteristics of the display are examined. >

Novel Thin-Film α-Si Approach to Drive Active Matrices Displays

High information content liquid crystal displays (minimum 250 × 250 picture elements) operated in the fast update (TV) mode require the incorporation of an electronic switch into each picture element. α-Si:H(F)1 is a suitable material for the implementation of both two (diode) and three (TFT) terminal devices for matrix addressed LCDs. A simple analysis of α-Si TFTs shows that the low mobility of α-Si is an optimal match to the Ioff requirements. while competing technologies (CdSe, poly-Si) encounter difficulties. However. using 10μ channel lengths, the mobility of α-Si was considered insufficient to drive active matrix displays. We report an innovative α-Si TFT which achieves short channel length and high mobility. The DC and the transient response characteristics will be presented. Ring oscillators were designed using this characteristic. Computer simulations suggest that an eleven stage ring oscillator utilizing α-Si TFTs can operate at 2.2 MHz. These advances will allow us to overcome the limitations ...

Short Channel Length Planar Tft's Using Amorphous Silicon Alloys

There is a rapid growth of interest in the application of amorphous silicon alloy thin film devices to large area microelectronic circuits. Increased current levels are a constant goal since gains in device current result in proportional gains in power and speed. Mobility limitations in amorphous silicon thin film transistors have directed interest toward short conduction channel devices to achieve higher current levels; furthermore, compatibility with large area processing makes photolithography with 10μm feature size very attractive. Consequently, innovative techniques, which define channel lengths by processing parameters rather than by mask feature size are necessary. Previous work has applied such techniques to vertical structure TFTs which define channel lengths by the vertical height of deposited layers. Here, we report on a technique which achieves short channel lengths in planar structures using etching parameters to define short channel lengths. Amorphous silicon alloy TFTs have been fabricated with channel lengths of ≈2μm which reach currents of lma. These techniques broaden the range of application of amorphous silicon alloy TFTs by providing devices capable of operating at higher currents and higher speeds.

VLSI Processing of Amorphous Silicon Alloy P-I-N Diodes For Active Matrix Applications

A number of new amorphous silicon alloy microelectronic devices, including LCD active matrix displays, linear image sensors, and thin film multilayer computer memories, have been developed in our company. These applications rely heavily on the quality of the intrinsic semiconductor as well as its ability to withstand the many processing steps used in a modern photolithographic process. In this paper, we present electrical data on amorphous silicon alloy p-i-n diodes after such a process. These devices have an active area of 20μm × 20μm defined using standard photolithographic techniques and etched using a dry etch process. These diodes are characterized by ideality factors (n) of 1.4 and extrapolated reverse saturation current densities of 10 13 A/cm 2 h. The diodes exhibit nearly 10 orders of magnitude rectification at ± 3V and the reverse bias current density remains below 10 -8 A/cm 2 for reverse bias voltages of -15V. In pulsed forward bias, these diodes can be operated at current densities greater than 300A/cm 2 . Thin film amorphous silicon diodes moreover have the advantage that varying the thickness of the intrinsic layer allows the optimization of parameters such as the capacitance per unit area, the reverse bias current density and the forward bias conductance per unit area. We find that these devices are fully compatible with state of the art VLSI processing techniques and are suitable for applications in integrated circuit structures, for example rectification devices in microelectronic arrays and isolation devices in display matrices.