Nondestructive characterization technique helps gallium nitride crystal developments

IMAGE: Measurement system and observation picture of TDs in GaN semiconductor by multiphoton excitation photoluminescence technique. TDs are observed as dark lines.
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Credit: Osaka University

Osaka – Gallium nitride (GaN) is a semiconductor product whose broad band space might one day cause it superseding silicon in electronic devices applications. It is for that reason crucial to have GaN characterization methods that have the ability to support the advancement of GaN gadgets. Researchers at Osaka University have actually reported a nondestructive technique for defining the crystalline quality of GaN. Their findings were released in Applied Physics Express.

GaN power changing gadgets use various benefits consisting of high-speed changing, high-power operation, low on-resistance, and high breakdown voltage. To benefit from these residential or commercial properties, the flaw density of GaN crystals should be low.

Threading dislocations (TDs) are a kind of crystal flaw produced by the flaw of crystals that propagate from the substrate into an epitaxial layer. These TDs typically function as leak present courses.

TDs can be categorized utilizing their Burgers vectors. A range of techniques can be utilized to examine GaN and identify the Burgers vectors of the TDs; nevertheless, the majority of have actually associated constraints, such as included sample preparation or minimal analysis location. The methods might likewise need devastating sample preparation, so checked samples cannot be recycled.

The scientists for that reason utilized multiphoton excitation photoluminescence (MPPL) to assess GaN. MPPL is a nondestructive technique in which the excitation laser light permeates deep into the samples. It is for that reason perfect for the three-dimensional (3D) examination of crystal problems in products.

“We used MPPL to carry out an in-depth study of defects in GaN crystals by analyzing the local photoluminescence properties and the 3D defect structures,” discusses research study very first author Mayuko Tsukakoshi. “Considering our findings along with those of the etch pit method then allowed for statistical classification of the TDs.”

The combined TDs were discovered to extend through GaN at big disposition angles. In addition, the contrast of the photoluminescence signals showed that the screw TDs had more powerful nonradiative residential or commercial properties than the others.

“Being able to relate MPPL findings to the quality of GaN crystals provides an excellent tool for nondestructive, high throughput substrate evaluation,” research study matching author Tomoyuki Tanikawa states. “We believe our findings will help to easily identify defects that affect reliability, as well as improve yields to give more efficient routes to GaN devices.”


The short article, “Identification of Burgers vectors of threading dislocations in free-standing GaN substrates via multiphoton-excitation photoluminescence mapping,” was released in Applied Physics Express at DOI:

About Osaka University

Osaka University was established in 1931 as one of the 7 royal universities of Japan and is now among Japan’s leading extensive universities with a broad disciplinary spectrum. This strength is combined with a particular drive for development that extends throughout the clinical procedure, from basic research study to the production of used technology with favorable financial effects. Its dedication to development has actually been acknowledged in Japan and around the globe, being called Japan’s most ingenious university in 2015 (Reuters 2015 Top 100) and among the most ingenious organizations on the planet in 2017 (Innovative Universities and the Nature Index Innovation 2017). Now, Osaka University is leveraging its function as a Designated National University Corporation picked by the Ministry of Education, Culture, Sports, Science and Technology to add to development for human well-being, sustainable advancement of society, and social change.


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