Accession Number:

AD1105480

Title:

Annealing Induced Interfacial Evolution of Titanium/Gold Metallization on Unintentionally Doped Beta-Ga2O3

Descriptive Note:

Journal Article - Open Access

Corporate Author:

University of Michigan Ann Arbor United States

Personal Author(s):

• Lee,Ming-Hsun
• Peterson,Rebecca L.

Report Date:

2019-03-26

Pagination or Media Count:

4.0

Abstract:

Here, we study the kinetic evolution of the interface between a TiAu metal stack and bulk 010 -Ga2O3 substrate under different annealing conditions using scanning transmission electron microscopy. We observe distinct processes of interfacial reaction and interdiffusion between the metal films and at the metal-semiconductor junction. Upon rapid thermal annealing RTA, the as-deposited Ti readily reacts at the Beta-Ga2O3 interface, driven by redox favorability. After a 1-min 470C N2 RTA, the interface exhibits two segregated crystalline layers a 5 nm Ti-rich Ti-TiOx layer lattice-matched to the -Ga2O3 substrate and a 3 nm Ga-rich TiGaxlayer. A substitutional mechanism is proposed based on the similarity in ionic radii of Ti3, Ti4, and Ga3. After 15-min RTA, the Ga-rich layer is diluted within the Ti-Au matrix, while the Ti-TiOx layer does not significantly change, and there is no further observable Ga out-diffusion from the substrate. Thus, we propose that the Ti-TiOx layer acts as a diffusion barrier, even when it is no longer lattice-matched with -Ga2O3. In addition, Ti-rich nanocrystals form within the Ti-Au layer, presumably via the proceeding reactions. The observations here provide insights for contact stack evolution during operation of power electronic devices at elevated temperature.

Descriptors:

• metal semiconductor junctions
• transmission electron microscopy
• compound semiconductors
• power electronics
• electron microscopy
• electron mobility
• metal oxides

Subject Categories:

• Electrical and Electronic Equipment

Distribution Statement:

APPROVED FOR PUBLIC RELEASE