Field effect transistor having a surface channel and its method of operation
First Claim
1. A field effect transistor, comprising:
- a semiconductor substrate of a first conductivity type;
a source zone and a drain zone each of a second conductivity type spaced apart in said substrate;
a surface channel of the second conductivity type adjoining the surface of said substrate in an area between said source and drain zones;
a gate electrode carried over said surface channel;
a surface depletion zone; and
a second channel in said surface depletion zone below said surface channel and extending between and connecting said source and drain zones below the surface of said substrate, said second channel including dopant particles having an energy level in the forbidden band of the semiconductor substrate which, at an operating temperature T, lies at a distance of more than 1/2 kT from the conduction band edge and valance band edge of said semiconductor substrate, where k is the Boltzmann constant, and whereat, by an electric field induced ionization, an additional conductivity occurs which causes a negative differential resistance.
0 Assignments
0 Petitions
Accused Products
Abstract
A field effect transistor includes a semiconductor substrate of a first conductivity having a source zone and a drain zone of an opposite, second conductivity spaced apart therein and extending to the surface thereof. A surface channel adjoins the surface, is of the second conductivity, and extends in an area located between the source and drain zones. A gate electrode is carried above the surface channel, either on an insulator, or directly on the surface to form a Schottky junction. A second zone lies beneath the surface below or in overlapping relation to the surface channel and extends between the drain and source zones. The second channel is doped with dopant particles whose energy level in the forbidden band of the semiconductor substrate, at an operating temperature T, lies at a distance of more than 1/2 kT from the conduction band edge and valence band edge of the semiconductor substrate. Application of proper potentials with respect to the start voltage required for ionization of the dopant particles in the second channel causes the field effect transistor to function as a high-speed switch. Connection of the field effect transistor in series with a resistance between the poles of a power supply which has a voltage greater than the start voltage causes the field effect transistor to operate, in combination with the resistor, as an oscillator.
39 Citations
17 Claims
-
1. A field effect transistor, comprising:
-
a semiconductor substrate of a first conductivity type; a source zone and a drain zone each of a second conductivity type spaced apart in said substrate; a surface channel of the second conductivity type adjoining the surface of said substrate in an area between said source and drain zones; a gate electrode carried over said surface channel; a surface depletion zone; and a second channel in said surface depletion zone below said surface channel and extending between and connecting said source and drain zones below the surface of said substrate, said second channel including dopant particles having an energy level in the forbidden band of the semiconductor substrate which, at an operating temperature T, lies at a distance of more than 1/2 kT from the conduction band edge and valance band edge of said semiconductor substrate, where k is the Boltzmann constant, and whereat, by an electric field induced ionization, an additional conductivity occurs which causes a negative differential resistance. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
-
-
13. A method of providing a high-speed field effect transistor switch, beginning with a transistor including a semiconductor substrate of a first conductivity type, a source zone and a drain zone each of a second conductivity type spaced apart in the substrate, the source and drain zones carrying respective source and drain electrodes, a surface channel of the second conductivity type adjoining the surface of the substrate in an area between the source and drain zones, and a gate electrode carried over the surface channel, comprising the steps of:
-
forming a second channel below said surface channel between and connecting the source and drain zones, with dopant particles having an energy level in the forbidden band of the semiconductor substrate which, at an operating temperature T, lies at a distance of more than 1/2 kT from the conduction band edge and the valance band edge of the semiconductor substrate, where k is the Boltzmann constant; applying zero potential to the source electrodes; applying a voltage to the gate electrode which is lower than the start voltage required for ionization of the dopant particles in the second channel; applying a voltage to the drain electrode which is lower than the start voltage and greater than the voltage applied to the gate electrode; and raising the voltage applied to the drain electrode to a value which exceeds the start voltage. - View Dependent Claims (14)
-
-
15. A method of providing a field effect transistor oscillator beginning with a field effect transistor which comprises a semiconductor substrate of a first conductivity type, a source zone and a drain zone each of a second conductivity type spaced apart in the substrate, the source and drain zones carrying respective electrodes, a surface channel of the second conductivity type adjoining the surface of the substrate in an area between the source and drain zones, and a gate electrode carried over the surface channel, comprising the steps of:
-
forming a second channel below said surface channel between and connecting the source and drain zones, with dopant particles having an energy level in the forbidden band of the semiconductor substrate which, at an operating temperature T, lies at a distance of more than 1/2 kT from the conduction band edge and the valance band edge of the semiconductor substrate, where k is the Boltzmann constant; and connecting the source and drain electrodes of the transistor in series with a resistor between the poles of a voltage source having a potential which is greater than the start voltage required for ionization of the dopant particles in the second channel. - View Dependent Claims (16, 17)
-
Specification