SEMICONDUCTOR SUBSTRATE AND SEMICONDUCTOR ELEMENT

摘要

PROBLEM TO BE SOLVED: To provide a semiconductor substrate which can achieve high resistance in a region of a high-resistance layer on a channel layer side while decreasing a carbon concentration and a transition metal concentration in the channel layer; and provide a semiconductor element manufactured by using the semiconductor substrate.SOLUTION: A semiconductor substrate comprises: a substrate; a buffer layer on the substrate; a high-resistance layer on the buffer layer, which is composed of a nitride semiconductor and contains transition metal and carbon; and a channel layer on the high-resistance layer, which is composed of a nitride semiconductor. The high-resistance layer has a decrease layer which contacts the channel layer and has a concentration of the transition metal, which decreases from the buffer layer side toward the channel layer side. A decrease rate of a carbon concentration decreasing toward the channel layer is larger than a decrease rate of the transition metal concentration decreasing toward the channel layer.