Shin-Etsu Chemical has determined that QST® substrate is an essential material for the social implementation of high-performance, energy-efficient GaN power devices, and the company will promote the development and launching on the market of these products.

Since QST substrate is designed to have the same coefficient of thermal expansion (CTE) as GaN, it enables suppression of warpage and cracking of the GaN epitaxial layer and resultant large-diameter, high-quality thick GaN epitaxial growth.

Taking advantage of these characteristics, it is expected to be applied to power devices and RF devices (5G and beyond 5G), which have been rapidly growing in recent years, as well as in such areas as MicroLED growth for MicroLED displays.

In addition to sales of QST substrates, Shin-Etsu Chemical will also sell GaN grown QST substrates upon customer request. We currently have a line-up of 6″ and 8″ diameter substrates, and we are working on 12″ diameter substrates.

Since 2021, for each respective application for power devices, RF devices and LEDs, sample evaluation and device development are continuing with numerous customers in Japan and globally. Especially for power devices, continuous evaluation is underway for devices in the wide range of 650V to 1800V.

So far, Shin-Etsu Chemical has repeatedly made many improvements with regard to its QST substrates. One example is the significant improvement in lowering defects originating from the bonding process, which has enabled the supply of high-quality QST substrates. In addition, for the thicker GaN films that many of our customers have requested, we have promoted the provision of template substrates with optimized buffer layers, which enables our customers to realize stable epitaxial growth of more than 10 μm thickness.

Furthermore, various successful results have been produced and reported on, including the achievement of thick-film GaN growth exceeding 20 μm using QST substrates and the achievement of 1800V breakdown voltage2 in power devices.