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Sensitive Technique to Characterize MgO Films used in AC

IP.com Disclosure Number: IPCOM000052563D
Original Publication Date: 1981-Jun-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 2 page(s) / 14K

Publishing Venue

IBM

Related People

Aboelfotoh, MO: AUTHOR [+2]

Abstract

Gaseous discharge display devices are generally fabricated by forming conductors on glass plates or substrates, overcoating the conductors with a layer of dielectric material, such as lead-borosilicate glass containing a high percentage of lead oxide, and utilizing a coating of refractory high secondary electron emissive material, such as magnesium oxide, over the dielectric layer to protect the dielectric surface against degradation from ion bombardment and provide lower operating voltages. The glass substrates are then edge sealed to form a gaseous discharge display panel, the panel is evacuated, and a Penning gas mixture, such as Ne+0.1%Ar, is introduced into the panel under a less than atmospheric pressure during a backfill operation.

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Sensitive Technique to Characterize MgO Films used in AC

Gaseous discharge display devices are generally fabricated by forming conductors on glass plates or substrates, overcoating the conductors with a layer of dielectric material, such as lead-borosilicate glass containing a high percentage of lead oxide, and utilizing a coating of refractory high secondary electron emissive material, such as magnesium oxide, over the dielectric layer to protect the dielectric surface against degradation from ion bombardment and provide lower operating voltages. The glass substrates are then edge sealed to form a gaseous discharge display panel, the panel is evacuated, and a Penning gas mixture, such as Ne+0.1%Ar, is introduced into the panel under a less than atmospheric pressure during a backfill operation.

The predominant aging characteristics exhibited by such gaseous discharge display devices are the decrease in the maximum sustain voltage and hence the bistable voltage margin with time. In order for the device to operate successfully, the bistable voltage margins of individual display cells must not change with time beyond the point where they no longer encompass the voltage originally chosen to sustain the device. These aging trends are generally characterized by extensive life testing (in excess of 1000 hours) which is a costly and time consuming process.

It is found that these aging characteristics are typical of oxygen-deficient MgO films, resulting from deposition of these films at a low temperature (25 Degrees C). Oxygen deficiency results in donor-like energy levels in the energy band gap of MgO, thus allowing the secondary electron emission coefficient, Gamma(Ar), of argon ions to have a nonzero value. It is also found that even a very small value of Gamma(Ar), has a substantial effect on the maximum sustain voltage and hence the bistable voltage margin of gaseous discharge display panels at gas pressures higher than those at which the panels are normally operated. For example, for Gamma(Ar)=0, the bistable voltage margin remains essentially unchanged as the gas pressure is increased from 350 torr to 750. On the other, hand, for Gamma(Ar)=0.03 which is typical of the 25 Degrees C deposited MgO films, increasing the gas pressure from 350 torr to 750 Degrees C red...