METHOD FOR PRODUCING SUBSTRATE FOR GROUP III NITRIDE SEMICONDUCTOR ELEMENT FABRICATION, METHOD FOR PRODUCING GROUP III NITRIDE SEMICONDUCTOR FREE-STANDING SUBSTRATE OR GROUP III NITRIDE SEMICONDUCTOR ELEMENT, AND GROUP III NITRIDE GROWTH SUBSTRATE

摘要

Provided is a method for producing a substrate for group III nitride semiconductor element fabrication with an improved area ratio of chromium nitride microcrystals with a triangular pyramid shape in a chromium nitride layer surface. That is, there is provided a method for producing a substrate for group III nitride semiconductor element fabrication comprising a depositing step of forming a chromium layer on a base substrate for growth, a nitriding step of nitriding the chromium layer under prescribed conditions to form a chromium nitride layer, and a crystalline layer growth step of epitaxially growing at least one layer of a group III nitride semiconductor layer on the chromium nitride layer, characterized in that the chromium layer is deposited by a sputtering method such that the deposition rate is in the range of 7 to 65 Å/sec in the sputtering particle range and the thickness is in the range of 50 to 300 Å, the chromium nitride layer is formed in a MOCVD growth furnace with a furnace pressure of 6.666-66.66 kPa and a temperature of 1,000°C or more in a gas atmosphere containing ammonia gas, the gas component other than the ammonia gas in the gas atmosphere is a carrier gas comprising a nitrogen gas and a hydrogen gas, and the content ratio of the nitrogen gas in the carrier gas is in the range of 60 to 100 volume%.