4-inch GaN HEMT Epi wafers with Less Wafer Bow

Takeshi Tanaka* **, Kazuto Takano*, Hajime Fujikura*, Tomoyoshi Mishima*, Yoshiharu Kohji**, Hiroyuki Kamogawa**, Takeshi Meguro** and Yohei Otoki**

*Hitachi Cable, Ltd., Advanced Technology Laboratories, Materials Technology Research Center
**Hitachi Cable, Ltd., Semiconductor Engineering Dept.
Isagozawa 800, Hitachi City, Ibaraki 319-1418, Japan
Phone: +81-294-42-5071 Fax: +81-294-42-6410
Email: tanaka.takeshi@hitachi-cable.co.jp

Feasibility study to reduce the bow or large diameter GaN HEMT epiwafers on sapphire substrates was performed. The warp of 4-inch GaN HEMT epiwafer including coalescence-promoted buffer layer by MOVPE was reduced to no more than 22.7 µm. Despite the thin buffer layers, high electron mobility of 1.457 cm²/Vs and 436.1 Ohm/sq. sheet resistance was achieved in the developed sample. Prevention of facet formation at the initial stage of the buffer process by applying high temperature coalescence-promoted growth is responsible for the decent electrical characteristics.

Keywords: GaN, HEMT, MOVPE, Epitaxy, Wafer Bow

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