High-voltage amorphous silicon thin-film transistors

Author

Martin, Russel A. ; Da Costa, Victor M. ; Hack, Michael ; Shaw, John G.

Author_Institution

Xerox PARC, Palo Alto, CA, USA

Volume

40

Issue

3

fYear

1993

fDate

3/1/1993 12:00:00 AM

Firstpage

634

Lastpage

644

Abstract

High-voltage MOSFETs have been fabricated in a large-area thin-film amorphous silicon technology. The transistors have an offset gate structure which allows them to operate at an excess of 400 V. Basic fabrication steps and structure are discussed. These transistors have a gate-controlled region in series with an offset region where the current is space charge limited. The I_D-V_D characteristics exhibit a unique instability under drain voltage stress; there is a parallel shift in the I_D versus V_D characteristic to a higher V_D. This instability arises from the creation of localized states in the a-Si during depletion. It is analyzed through experiment and two-dimensional simulation. Structural variations are described, including the application of a field plate, to stabilize transistor drive current. Reliability and process uniformity are discussed for arrays of transistors. An appropriate circuit simulation model is discussed. Operation of output drive circuits with high-voltage thin-film transistors (TFTs) is shown, and the application of these to an electrographic plotter is described

Keywords

amorphous semiconductors; elemental semiconductors; insulated gate field effect transistors; power transistors; silicon; simulation; thin film transistors; 400 V; HV device; I/V characteristics; MOSFETs; TFTs; amorphous Si; circuit simulation model; drain voltage stress; electrographic plotter; fabrication; field plate; gate-controlled region; high-voltage; instability; large-area; localized states; offset gate structure; offset region; output drive circuits; process uniformity; reliability; space charge limited current; thin-film transistors; transistor arrays; two-dimensional simulation; Amorphous silicon; Circuit simulation; Fabrication; MOSFETs; Semiconductor thin films; Space charge; Space technology; Stress; Thin film transistors; Voltage;

fLanguage

English

Journal_Title

Electron Devices, IEEE Transactions on

Publisher

ieee

ISSN

0018-9383

Type

jour

DOI

10.1109/16.199371

Filename

199371