Abstract: A semiconductor device includes: a substrate; a channel layer disposed on the substrate, wherein the channel layer is made of GaN; a barrier layer disposed on the channel layer, wherein the barrier layer is made of AlzGa1-zN; and an inserting structure inserted between the channel layer and the barrier layer. The inserting structure includes: a first inserting layer disposed on the channel layer, wherein the first inserting layer is made of AlxGa1-xN; and a second inserting layer disposed on the first inserting layer, wherein the second inserting layer is made of AlyGa1-yN, and y is greater than x. The semiconductor device further includes: a gate electrode disposed on the barrier layer; a source electrode and a drain electrode disposed on the barrier layer and respectively at opposite sides of the gate electrode; and a spike region formed below at least one of the source electrode and the drain electrode.

Abstract: The present invention provides a method for measuring the trimethylamine N-oxide (TMAO) production capacity in a subject, which comprises the following steps: (a) making the subject intake a specific dosage of carnitine; and (b) obtaining a body fluid sample of the subject at a specific time point after the subject ingests the carnitine and detecting the TMAO content in the body fluid sample. Different from the general technical detection on the market that only detects the gut microbiome composition, the invention can directly detect the ability of gut microbiota to produce TMAO in the human body. In addition, compared with directly detecting the concentration of TMAO in the blood, the invention gives a better predictive effect of gut microbiota functional phenotypes.