Aluminum gallium nitride/gallium nitride high electron mobility transistors having a gate contact on a gallium nitride based cap segment and methods of fabricating same

Abstract

High electron mobility transistors (HEMTs) and methods of fabricating HEMTs are provided. Devices according to embodiments of the present invention include a gallium nitride (GaN) channel layer and an aluminum gallium nitride (AlGaN) barrier layer on the channel layer. A first ohmic contact is provided on the barrier layer to provide a source electrode and a second ohmic contact is also provided on the barrier layer and is spaced apart from the source electrode to provide a drain electrode. A GaN-based cap segment is provided on the barrier layer between the source electrode and the drain electrode. The GaN-based cap segment has a first sidewall adjacent and spaced apart from the source electrode and may have a second sidewall adjacent and spaced apart from the drain electrode. A non-ohmic contact is provided on the GaN-based cap segment to provide a gate contact. The gate contact has a first sidewall which is substantially aligned with the first sidewall of the GaN-based cap segment. The gate contact extends only a portion of a distance between the first sidewall and the second sidewall of the GaN-based cap segment.

Description

[0001] related application [0002] This application is related to and claims U.S. Provisional Patent No. 60 / 250755, filed December 1, 2000, entitled "AlGaN / GaN HEMT with Improved Gate Barrier Layer and Low Access Resistance" Priority of the application, the disclosure of which is incorporated herein as if filed in its entirety. [0003] Statement of Government Interest [0004] This invention was developed at least in part under Contract No. N00014-99-C-0657 of the Naval Research Institute. Therefore, the government has certain rights in this patent. technical field [0005] The present invention relates to a high electron mobility transistor (HEMT), and more particularly to an aluminum gallium nitride (AlGaN) / gallium nitride (GaN) high electron mobility transistor (HEMT). Background technique [0006] AlGaN / GaN HEMT (High Electron Mobility Transistor) devices are well known in the semiconductor field. US Patents 5192987 and 5296395 describe AlGaN / GaN HEMT structures an...

AI Technical Summary

Problems solved by technology

However, this approach is not suitable for AlGaN / GaN HEMT structures, because the upper surface of GaN is generally non-conductive, and there is no benefit in recessing the gate electrode downward toward the barrier layer.

Images