Abstract: A GaAs-InGaAs high electron mobility transistor includes: a GaAs substrate; a GaAs buffer layer overlaying on the GaAs substrate; a graded InGaAs channel overlaying on the GaAs layer; a GaAs spacer layer overlaying on the graded InGaAs channel layer; a .delta.-doping layer overlaying on the GaAs spacer layer; a GaAs cap layer overlaying on the .delta.-doping layer; drain and source terminals overlaying on the GaAs cap layer and contacting the graded InGaAs channel layer; and a gate terminal overlaying on the GaAs cover layer and located between the drain terminal and the source terminal.

Abstract: A manufacturing method of a MOSFET having a channel part on the side surface of a groove, which does not permit the introduction of defects or contaminant into the channel part and which can make the shape of the groove uniform. An n.sup.- -type epitaxial layer having a low impurity concentration is formed on a main surface of an n.sup.+ -type semiconductor substrate. This surface is specified as a main surface, and chemical dry etching is applied to a specified region of this main surface. A region including a surface generated by the chemical dry etching is selectively oxidized to form a selective oxide film to a specified thickness. Following this process, p-type and n-type impurities are doubly diffused from the main surface to define the length of the channel and form a base layer and a source layer. Furthermore, the n.sup.+ -type semiconductor substrate is specified as a drain layer.