US 12,224,172 B2
Group III nitride substrate with oxygen gradient, method of making, and method of use
Mark P. D'Evelyn, Vancouver, WA (US); Keiji Fukutomi, Vancouver, WA (US); Drew W. Cardwell, Camas, WA (US); David N. Italiano, Washougal, WA (US); and Chiaki Domoto, Vancouver, WA (US)
Assigned to SLT Technologies, Inc., Los Angeles, CA (US)
Filed by SLT Technologies, Inc., Los Angeles, CA (US)
Filed on Nov. 30, 2022, as Appl. No. 18/072,684.
Claims priority of provisional application 63/326,448, filed on Apr. 1, 2022.
Claims priority of provisional application 63/285,000, filed on Dec. 1, 2021.
Prior Publication US 2023/0167586 A1, Jun. 1, 2023
This patent is subject to a terminal disclaimer.
Int. Cl. B32B 27/02 (2006.01); C30B 29/40 (2006.01); H01L 21/02 (2006.01); C30B 7/10 (2006.01)
CPC H01L 21/02389 (2013.01) [C30B 29/406 (2013.01); H01L 21/02433 (2013.01); H01L 21/02595 (2013.01); C30B 7/105 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A free-standing crystal, comprising a group III metal and nitrogen, wherein the free-standing crystal comprises:
a wurtzite crystal structure;
a first surface having a maximum dimension greater than 40 millimeters in a first direction and a crystallographic orientation within 10 degrees of (0 0 0 1); and
a second surface on the opposite side of the crystal from the first surface, wherein a separation between the first surface and the second surface is between about 200 micrometers and about 2000 micrometers,
wherein an average oxygen concentration within a depth of 2 to 10 micrometers from the first surface, measured at at least four regions, is between 1×1016 cm−3 and 5×1019 cm−3 and is greater, by a factor between about 1.1 and about 10, than the average oxygen concentration within a depth of 2 to 10 micrometers from the second surface, measured at at least four regions, as quantified by calibrated secondary ion mass spectrometry.