Field effect transistor, preparation method thereof and switching circuit

Abstract

The invention provides a field effect transistor, a preparation method thereof and a switching circuit. The field effect transistor comprises a channel layer, a source electrode, a drain electrode, a gate structure and a gate metal layer, the gate structure comprises a P-type gallium nitride layer and an N-type gallium nitride layer which are stacked, so that a gate metal / pGaN Schottky diode is replaced by an nGaN / pGaN reverse biased diode, the gate voltage endurance capability of the field effect transistor can be improved, and the breakdown capability is improved. And the doping concentration of the P-type gallium nitride layer is 1 * 10 < 18 > cm <-3> to 1 * 10 < 19 > cm <-3>, so that the charge storage effect when the device works can be reduced, carriers in the pGaN layer are exhausted as much as possible, redundant charge storage is avoided, and the working threshold voltage stability of the device is improved. Ohmic contact is adopted between the gate metal layer and the gate structure, the reliability of connection between the gate metal layer and the gate structure can be improved, and therefore the reliability of the field effect transistor is improved.

Description

technical field [0001] The present application relates to the technical field of semiconductors, in particular to a field effect transistor, its preparation method and a switch circuit. Background technique [0002] Field effect transistors are widely used in various scenarios as circuit switch components, and GaN (gallium nitride)-based field effect transistors have high mobility and high chemical stability due to their material properties, and can be used as higher frequency switching applications. [0003] The GaN field effect transistor achieves the purpose of switching by controlling the on-off of the two-dimensional electron gas of the channel. GaN FETs are usually divided into two categories, one is normally-on FET, also known as depletion-type FET; the other is normally-off FET, also known as enhanced FET. However, due to the safety considerations of the power system, the switching device is generally required to be a normally-off device, and there are several ways...

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Problems solved by technology

However, the gate metal layer and the gate structure are generally in Schottky contact, and two back-to-back diodes are formed in the GaN field effect transistor, which makes the threshold voltage of the field effect transistor unstable due to the difficulty of charge discharge; and the gap between the gate metal layer and the gate structure Under the condition that the gate metal layer is biased by positive voltage, the Schottky diode between them is easy to break down when subjected to higher voltage

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