High electron mobility transistors

摘要

The present disclosure relates to a donor layer of bi-layer AlGaN and associated method of fabrication within a high electron mobility transistor (HEMT) configured to provide low-resistance ohmic source and drain contacts to reduce power consumption, while maintaining a high-mobility of a two-dimensional electron gas (2DEG) within a channel of the HEMT. The donor layer of bi-layer AlGaN comprises a mobility-enhancing layer of AlzGa(1-z)N, a resistance-reducing layer of AlxGa(1-x)N disposed over the mobility-enhancing layer, wherein the ohmic source and drain contacts connect to the HEMT. A channel layer of GaN is disposed beneath the mobility-enhancing layer, wherein a 2DEG resides, forming the channel of the HEMT.

主权项

1. A high electron mobility transistor (HEMT), comprising:
a channel layer disposed over a silicon substrate; a donor bi-layer disposed on and abutting the channel layer, the donor bi-layer comprising:
a mobility-enhancing layer of AlzGa(1-z)N disposed on and abutting the channel layer and having a molar fraction z in a first range;a resistance-reducing layer of AlxGa(1-x)N disposed on and abutting the mobility-enhancing layer and having a first molar fraction x in a second range less than the first range, wherein the mobility-enhancing layer of AlzGa(1-z)N has a first thickness value that is approximately twice a second thickness value of the resistance-reducing layer of AlxGa(1-x)N; and source and drain ohmic contacts, which contact the resistance-reducing layer of AlxGa(1-x)N; a first dielectric isolation layer continually contacting an upper surface of the resistance-reducing layer of AlxGa(1-x)N from a first position contacting the source ohmic contact to a second position contacting a gate structure contacting the resistance-reducing layer of AlxGa(1-x)N; and wherein the donor bi-layer has a conduction band energy that monotonically decreases from the source and drain ohmic contacts to the channel layer.