GaN-based high electron mobility transistor and method for making the same

Abstract

A high electron mobility transistor including: a GaN material system based heterostructure; a passivating nitride layer over the heterostructure and defining a plurality of openings; and a plurality of electrical contacts for the heterostructure and formed through the openings.

Description

FIELD OF INVENTION [0001] The present invention relates generally to transistors, and more particularly, to GaN based High Electron Mobility Transistors (HEMTs) and methods for making such transistors. BACKGROUND [0002] High Electron Mobility Transistors are known to be desirable in certain applications. One such application is microwave amplifiers. They are known to generally yield higher output power densities, lower noise figures, and be able to operate at higher frequencies as compared to other Field Effect Transistors (FETs). GaN material system based HEMT's are believed to be desirable for use in Radio Frequency (RF) modulation schemes and interfaces. [0003] However, drain current reduction at high frequencies has conventionally limited the available output power in GaN material system-based HEMT devices, which is believed to be caused by the surface states. It is believed desirable to passivate the surface states and prevent surface damage during device processing. Low breakd...

AI Technical Summary

Benefits of technology

[0004] A high electron mobility transistor including: a GaN material system based heterostructure; barrier surface protection during MESA processing; a front end passivating dielectric layer over the heterostructure and defining a plurality of low damage etch processed openings for electrical ohmic contacts for source and drain electrodes and for Schottky contacts for gate electrodes on the heterostructure through the openings; ohmic contact opening surface treatments and source / drain ion implantation to reduce contact and source / drain resistance; and a double heterostructure for improved carrier confinement.

Problems solved by technology

However, drain current reduction at high frequencies has conventionally limited the available output power in GaN material system-based HEMT devices, which is believed to be caused by the surface states.

Low breakdown voltage has conventionally limited high drain biases for GaN material system based HEMT devices.

Further, the power performance of conventional GaN material system based HEMT devices typically degrades at high junction temperatures, due to reduced carrier saturation velocity and increased parasitic resistance.

Repeatable low contact resistance in conventional GaN material system based HEMT devices has also proven problematic for high frequency operation.

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