Field effect transistor

Claim 2

A field effect transistor comprising a high resistance basic semiconductor body of a first type of conductivity, a lowresistance semiconductor layer of said first type of conductivity provided on said basic semiconductor body and forming a channel region, two main electrodes spaced apart on said low-resistance semiconductor layer, and a mesa-like semiconductor area on said low-resistance semiconductor region between said two main electrodes and including a control region of a second type of conductivity at the free surface of said mesa-like semiconductor area and an intermediate region of said first type of conductivity which is less doped than said low-resistance semiconductor layer between said low-resistance semiconductor layer and said region of said second type of conductivity.

Claim 3

A field effect transistor as defined in claim 1, wherein said channel region has a specific resistance of about 0.1 ohm cm and said intermediate region has a specific resistance of about 1 ohm cm.

Claim 4

A field effect transistor as defined in claim 1, wherein said channel region, said control region and said intermediate region are epitaxially formed regions.

Claim 5

A field effect transistor comprising, in combination: a high-resistance basic semiconductor body of a first conductivity type; a low-resistance semiconductor layer of said first conductivity type on a major surface of said semiconductor body to provide a channel region for the transistor; a pair of spaced main electrodes ohmically contacting said low resistance semiconductor layer; a mesa-like semiconductor region on the portion of the major surface of said low-resistance semiconductor layer between said main electrodes, said mesa-like semiconductor region including a semiconductor region of said first conductivity type which is more weakly doped than said low-resistance semiconductor layer and which contacts said major surface of said low-resistance semiconductor layer, and a semiconductor control region of the opposite conductivity type extending along the free major surface of said mesa-like semiconductor region and spaced from said low-resistance semiconductor layer by said more weakly doped semiconductor region; and a control electrode ohmically contacting said semiconductor control region.

Claim 6

A field effect transistor comprising, in combination: a high-resistance basic semiconductor body of a first conductivity type; a low-resistance semiconductor layer of said first conductivity type on a major surface of said semiconductor body to provide a channel region for the transistor; a pair of spaced main electrodes ohmically contacting said low resistance semiconductor layer; a mesa-like semiconductor region on the portion of the major surface of said low-resistance semiconductor layer between said main electrodes, said mesa-like semiconductor region including a semiconductor region of said first conductivity type which is more weakly doped than said low-resistance semiconductor layer and which contacts said major surface of said low-resistance semiconductor layer, and a semiconductor control region of the opposite conductivity type extending along the free major surface of said mesa-like semiconductor region and spaced from said low-resistance semiconductor layer by said more weakly doped semiconductor region; and a control electrode ohmically contacting said semiconductor control region.

Claim 7

A field effect transistor as defined in claim 4 wherein said low-resistance semiconductor region has a specific resistance of about 0.1 ohm cm and said more weakly doped semiconductor region has a specific resistance of about 1.0 ohm cm.

Claim 8

A field effect transistor as defined in claim 4 wherein said low-resistance semiconductor layer, said semiconductor control region and said more weakly doped semiconductor region are epitaxially formed regions.