Patent ID: 6580125
Filing Date: 2003-06-17
Classification: H01L

Abstract:
A semiconductor device characterized by comprising:a semiconductor substrate; a compound semiconductor layer formed on the principal surface of the semiconductor substrate; a gate insulating film formed on the compound semiconductor layer; a gate electrode formed on the gate insulating film; a source electrode formed at a side of the gate electrode on the compound semiconductor layer; a drain electrode formed on a face of the semiconductor substrate, the face being opposed to the principal surface of the semiconductor substrate; a source region, which is formed in the compound semiconductor layer and contains an impurity of a first conductivity type, the source region being present from under a part of the source electrode to under associated edges of the gate electrode; an active region, which is formed in the compound semiconductor layer, contains an impurity of the first conductivity type, and functions as a region where carriers travel, the active region being located beneath the gate electrode; a drift region, which is formed in the compound semiconductor layer and contains an impurity of the first conductivity type, the drift region being located under the gate electrode; an oppositely doped region, which is formed between the drift region and the source region in the compound semiconductor layer and contains an impurity of a second conductivity type, wherein the active region includes one or more first semiconductor layers and one or more second semiconductor layers which contain an impurity for carriers at a concentration higher than the one or more first semiconductor layers and are smaller in film thickness than the one ore more first semiconductor layers and from which carriers spread out to the one or more first semiconductor layers due to a quantum effect.