Patent ID: 6015981
Filing Date: 2000-01-18
Classification: H01L

Abstract:
A heterostructure field effect transistor with a high modulation effectivity, comprising: a semiconductor substrate; a semiconductor heterostructure layer sequence deposited on a surface of the semiconductor substrate and including a buffer layer formed on the surface of the substrate, a first supply layer formed on the surface of the buffer layer, a layer packet composed of a plurality of pairs of undoped layers of different semiconductor materials with each pair forming a respective heterojunction to provide at least two heterojunctions and at least two n-conducting channels (n-HFET) or p-conducting channels (p-HFET), a second supply layer formed on the layer packet, and an undoped cover layer formed on the second supply layer; first and second laterally spaced ohmic contacts on the surface of the cover layer; and a control electrode for the transistor disposed on the surface of the cover layer between the first and second ohmic contacts; and wherein the substrate is a high-ohmic silicon substrate with a specific resistance of at least 10.sup.2 .OMEGA.cm.