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Lateral Bipolar Transistor Having a Negative Resistance Characteristic

IP.com Disclosure Number: IPCOM000075509D
Original Publication Date: 1971-Sep-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Broom, RF: AUTHOR

Abstract

The figure shows a generalized cross-section of the device. A thin conducting layer is deposited on an insulating substrate. Base, collector and emitter electrodes are attached respectively, with an ohmic contact, a Schottky contact, and a heavily doped region of opposite conductivity type to that of the conducting layer. Thus the transistor may be thought of as a base region having PN-junction emitter and a Schottky barrier collector.

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Lateral Bipolar Transistor Having a Negative Resistance Characteristic

The figure shows a generalized cross-section of the device. A thin conducting layer is deposited on an insulating substrate. Base, collector and emitter electrodes are attached respectively, with an ohmic contact, a Schottky contact, and a heavily doped region of opposite conductivity type to that of the conducting layer. Thus the transistor may be thought of as a base region having PN-junction emitter and a Schottky barrier collector.

Application of forward bias between base and emitter causes minority carriers to be injected into the channel. Provided L is very small most of the minority carriers are swept into the depletion zone beneath the Schottky collector. For efficient injection, it is necessary that the doping concentration of the emitter be much greater than that of the channel. With these conditions, only a small base current flows in the undepleted region c beneath the collector contact. Typical values for L are in the order of 1 Mu m or below.

At small collector reverse bias and with constant base-emitter voltage applied, a large reverse current flows between collector and base because of the lower diffusion voltage of the Schottky contact compared to the emitter-base junction. In this condition, very little current flows through the emitter. Increasing reverse bias on the collector with constant forward bias between base and emitter eventually reverses the direction of current fl...