ALEXANDRIA, Va., Sept. 23 -- United States Patent no. 12,421,621, issued on Sept. 23, was assigned to NGK INSULATORS Ltd. (Nagoya, Japan).
"Underlying substrate" was invented by Hiroshi Fukui (Obu, Japan), Morimichi Watanabe (Nagoya, Japan) and Jun Yoshikawa (Nagoya, Japan).
According to the abstract* released by the U.S. Patent & Trademark Office: "Provided is a ground substrate includes an orientation layer used for crystal growth of a nitride or oxide of a Group 13 element. The front surface of the orientation layer on the side used for the crystal growth is composed of a material having a corundum-type crystal structure having an a-axis length and/or c-axis length larger than that of sapphire. A plurality of pores are present in the o...