Cheaper, higher quality GaN freestanding substrates using N polarity control.

Overview of Technology

Nitride semiconductor free-standing substrate production method
This invention relates to a technique for producing high-quality nitride semiconductor freestanding substrates at a lower cost. The invention also includes the use of SCAlMgO4 substrates as seed crystals. The dislocation density of nitride semiconductors on this substrate becomes lower. By controlling the crystal polarity, the crystal diameter can be expanded as well as the thickness of the nitride semiconductor.

Comparison with Conventional Technology

It is possible to fabricate freestanding nitride semiconductor substrates with lower through-dislocation density than conventional substrates. Furthermore, the cleavage property of ScMgAlO4, which serves as the substrate, facilitates the exfoliation of the nitride semiconductor and reduces the cost of substrate fabrication.

Features and Uniqueness
  • Usage of ScAlMgO4 as a source substrate.
  • Expansion of crystal diameter by using N-polar growth
  • When ScAlMgO4 is used as the seed crystal and AlN is formed as the surface protective layer of this crystal, the surface shall be further nitrided after oxidation of the surface.
  • The main surface of the seed crystal shall be inclined 0.4 to 1.2° from the c-plane.
Practical Application

This invention is to provide high-quality, low-cost free-standing nitride semiconductor substrates for optical devices such as light-emitting diodes and lasers, and transistors operated under high power, high voltage, and high frequency. Companies are expected to verify the commercialization of the product.



New Industry Creation Hatchery Center

Takashi Matsuoka, Specially Appointed Professor(Research)
Doctor of Engineering