GaN device with mixed polarity

Abstract

The invention discloses a GaN device with the mixed polarity. The GaN device relates to the technical field of field effect transistors with two-dimensional carrier gas channels. The GaN device comprises a substrate layer, an N-polar GaN buffer layer, a first N-polar Alx GaN layer with a gradually increased Al component x, a second N-polar AlxGaN layer with a constant Al component x, a third N-polar AlxGaN layer with a gradually reduced Al component x, and a Ga-polar GaN channel layer. By virtue of the structure, a GaN based material with higher quality can grow epitaxially and the surface density and migration rate of 2DEG in a channel can be increased; and meanwhile a device with smaller ohmic contact resistance can be fabricated on a material with the mixed polarity by adopting a conventional Ga-polar GaN based device fabrication process.

Description

technical field [0001] The invention relates to the technical field of field effect transistors with two-dimensional carrier gas channels, in particular to a mixed-polarity GaN device. Background technique [0002] GaN-based materials have attracted the attention of researchers for their wide bandgap, high breakdown electric field, and high saturation electron drift velocity in the application fields of microelectronics and optoelectronics, and have become the frontier and hotspot of global semiconductor research. Together with SiC and other materials And known as the most promising "third-generation semiconductor materials." [0003] Due to the lack of center inversion in wurtzite-structured GaN, resulting in a very strong spontaneous polarization phenomenon, there are two types of GaN polarity (Ga-polar) and nitrogen polarity (N-polar) for wurtzite-structured GaN. Polarized GaN. Due to the opposite polarity of the two materials, there are many differences between the two...

AI Technical Summary

Problems solved by technology

However, the study found that the Ti / Al-based ohmic contact metal directly deposited on the N-polarGaN in the N-polarGaN-based HEMT cannot achieve a smaller ohmic contact resistance after high-temperature annealing, because the Al metal in the Ti / Al-based metal After high-temperature annealing, it can penetrate the Ti metal layer into GaN and combine with N to form AlN

[0005] In Ga-polarGaN, the AlN and GaN will form an AlN / GaN heterojunction similar to the AlGaN / GaN heterojunction, thereby forming a two-dimensional electron gas (2DEG) in GaN at the interface of AlN and GaN, but in the N- 2DEG will not be generated in the heterojunction formed by AlN and N-polarGaN in polarGaN, but two-dimensional hole gas (2DHG) will be formed instead, because its polarity is 180° different from that of Ga-polarGaN

However, the existence of the 2DHG is bound to make the ohmic contact characteristics worse, so that a smaller ohmic contact resistance cannot be achieved in N-polarGaN-based HEMTs.

In order to obtain a smaller ohmic contact resistance, some literature reports use ohmic regeneration to reduce the ohmic contact resistance, but this method will increase the difficulty of the process, increase the device preparation time and increase the uncertainty of the process

Images