Low gate current junction field effect transistor device architecture

Abstract

A JFET is provided with a very low gate current. In tests the excess gate current above the theoretical minimum current for a similarly sized reverse biased p-n junction was not observed. The JFET includes a lightly doped top gate and doped regions beneath the drain of the JFET.

Description

FIELD OF DISCLOSURE[0001]The present disclosure relates to an improved architecture for junction field effect transistors, JFETs, which reduces excess gate current of a JFET, such that the gate current substantially matches the reverse bias diode current that would be expected from the reverse current flow of a reverse biased p-n junction.BACKGROUND[0002]Broadly speaking field effect transistors, FETs, modulate the width of a “channel” region of semiconductor in order to vary the magnitude of current flowing between current flow terminals of the device. These terminals are known as a drain and a source of the FET.[0003]The current is modulated by subjecting the channel region to an electric field which can alter the size of depletion regions with the FET. The electric field is generated by applying a voltage to a “gate” of the FET. The gate region is insulated from the channel. The way in which the isolation is achieved can be used to classify FETs.[0004]In one class of FET, the gat...

AI Technical Summary

Benefits of technology

This patent describes a type of transistor called a junction field effect transistor (JFET). The JFET has three main regions: a source region, a drain region, and a channel in between. The top gate is made to be very lightly doped, which depletes it during use. The first and second regions are positioned close to the top gate or are separated from it by less than double the depth of the top gate. There is also a third region that is opposite the second region and is doped with the same type of dopant. This third region helps to keep the current carriers away from the edges of the top gate, which reduces the likelihood of impact ionization and avoids excess gate current. Overall, this structure prevents damage to the transistor and ensures it operates correctly.

Problems solved by technology

As a result, during use the top gate becomes depleted.

Images