Electromagnetic radiation detectors

Claim 2

A photoconductive semiconductor device comprising: a substrate; a first layer of electromagnetic radiation sensitive semiconductor material of a given conductivity type and having a first energy bandgap on said substrate; a first region of a second layer of semiconductor material of the same conductivity type as said first layer of semiconductor material, but having a second energy bandgap greater than said first bandgap, and in electrical contact with said first layer; and a first ohmic contact means on and in electrical communication with said region of said second layer of semiconductor material and adapted to be connected to a first conductor of an external source of electrical voltage in a manner such that said first ohmic contact will attract minority carriers; a second ohmic contact means on and in electrical communication with either said first or said second layer of semiconductor material and adapted to be connected to a second conductor of said external source of electrical voltage of opposite polarity to said first contact of said external source of electrical voltage; and wherein said first and second ohmic contact means on said semiconductor material are spaced from each other a sufficient distance such that external electromagnetic radiation may be sensed in the space therebetween.

Claim 3

A photoconductive semiconductor device comprising: a substrate; a first layer of electromagnetic radiation-sensitive semiconductor material of a given conductivity type and comprising a plurality of elemental species of a first percentage composition which produces a first energy bandgap; a first region of a second layer of electromagnetic radiation sensitive semiconductor material of the same conductivity type and comprising the same plurality of elemental species as said first layer of semiconductor material on said first layer of semiconductor material, but having a second percentage composition which produces a second energy bandgap greater than said first energy bandgap; a first ohmic contact means on and in electrical communication with said region of said second layer of semiconductor material and adapted to be connected to a first conductor of an external source of electrical voltage in a manner such that said first ohmic contact will attract minority carriers; and a second ohmic contact means on and in electrical communication with either said first or said second layer of semiconductor material and adapted to be connected to a second conductor of said external source of electrical voltage of opposite polarity to said first contact of said external source of electrical voltage; and wherein said first and second ohmic contact means on said semiconductor material are spaced from each other a sufficient distance such that external electromagnetic radiation may be sensed in the space therebetween.

Claim 4

A photoconductive semiconductor device comprising: a substrate; a first layer of electromagnetic radiation-sensitive semiconductor material of a given conductivity type and comprising a plurality of elemental species of a first percentage composition which produces a first energy bandgap; a first region of a second layer of electromagnetic radiation sensitive semiconductor material of the same conductivity type and comprising the same plurality of elemental species as said first layer of semiconductor material on said first layer of semiconductor material, but having a second percentage composition which produces a second energy bandgap greater than said first energy bandgap; a first ohmic contact means on and in electrical communication with said region of said second layer of semiconductor material and adapted to be connected to a first conductor of an external source of electrical voltage in a manner such that said first ohmic contact will attract minority carriers; and a second ohmic contact means on and in electrical communication with either said first or said second layer of semiconductor material and adapted to be connected to a second conductor of said external source of electrical voltage of opposite polarity to said first contact of said external source of electrical voltage; and wherein said first and second ohmic contact means on said semiconductor material are spaced from each other a sufficient distance such that external electromagnetic radiation may be sensed in the space therebetween.

Claim 5

The semiconductor device according to claim 1 wherein both of said ohmic contact means are on and in electrical communication with said second layer of semiconductor material.

Claim 6

The semiconductor device according to claim 2 wherein both of said ohmic contact means are on and in electrical communiction with said second layer of semiconductor material.

Claim 7

The semiconductor device according to any of claims 1, 2, 3 or 4 wherein said first layer of semiconductor material comprises Hg 1-x Cd x Te and where x is a number having a value between 0.1 and 0.4.

Claim 8

The semiconductor device according to claim 5 wherein said first layer of semiconductor material is Hg 1-x Cd x Te and wherein x is a number between 0.1 and 0.4; and wherein said second layer of semiconductor material comprises Hg 1-y Cd y Te wherein y is a number greater than x but less than unity.

Claim 9

The semiconductor device according to claim 6 wherein y exceeds x by at least 0.01.

Claim 10

The semiconductor device according to any of claims 1, 2, 3 or 4 wherein said first layer of semiconductor material is produced on said substrate by epitaxial formation.

Claim 11

The semiconductor device according to any of claims 1, 2, 3 or 4 wherein both said layers of semiconductor material are produced by liquid phase epitaxy.

Claim 12

The semiconductor device according to either of claims 3 or 4 wherein said second layer of semicondcutor material is coextensive with said first layer.

Claim 13

The semiconductor device according to either of claims 3 or 4 further comprising a second region of said second layer of semiconductor material substantially identical to said first region of said second layer of semiconductor material on said first layer of semiconductor material; and wherein said second ohmic contact is connected on said second region of said second layer of semiconductor material.

Claim 14

The semiconductor device according to any of claims 1, 2, 3 or 4 wherein said semiconductor material in both said layers is n-type.

Claim 15

A semiconductor device according to either of claims 1 or 2 wherein said first layer of said electromagnetic radiation-sensitive semiconductor material is one selected from the group consisting of InAs x Sb 1-x , In x Ga 1-x Sb, and Pb 1-x Sn x Te wherein x has a value greater than zero but less than unity.

Claim 16

A photoconductive semiconductor device comprising: a substrate; a first layer of Hg 1-x Cd x Te of a given conductivity type on said substrate, wherein x is a number having a value between 0.1 and 0.4; a first region of a second layer of Hg 1-y Cd y Te having the same conductivity type as said first layer of Hg 1-x Cd x Te material, wherein y is a number having a value greater than x but less than unity, on said first layer of semiconductor material; and a first ohmic contact means on and in electrical communication with said region of said second layer of semiconductor material and adapted to be connected to a first conductor of an external source of electrical voltage in a manner such that said first ohmic contact with attract minority carriers; and a second ohmic contact means on and in electrical communication with either said first or said second layer of semiconductor material and adapted to be connected to a second conductor of said external source of electrical voltage of opposite polarity of said first contact of said external source of electrical voltage; and wherein said first and second ohmic contact means on said semiconductor material are spaced from each other a sufficient distance such that external electromagnetic radiation may be sensed in the space therebetween.

Claim 17

A photoconductive semiconductor device comprising: a substrate; a first layer of Hg 1-x Cd x Te of a given conductivity type on said substrate, wherein x is a number having a value between 0.1 and 0.4; a first region of a second layer of Hg 1-y Cd y Te having the same conductivity type as said first layer of Hg 1-x Cd x Te material, wherein y is a number having a value greater than x but less than unity, on said first layer of semiconductor material; and a first ohmic contact means on and in electrical communication with said region of said second layer of semiconductor material and adapted to be connected to a first conductor of an external source of electrical voltage in a manner such that said first ohmic contact with attract minority carriers; and a second ohmic contact means on and in electrical communication with either said first or said second layer of semiconductor material and adapted to be connected to a second conductor of said external source of electrical voltage of opposite polarity of said first contact of said external source of electrical voltage; and wherein said first and second ohmic contact means on said semiconductor material are spaced from each other a sufficient distance such that external electromagnetic radiation may be sensed in the space therebetween.

Claim 18

A semiconductor device according to claim 14 wherein said conductivity is n-type.

Claim 19

The semiconductor device according to claim 14 wherein both of said ohmic contact means are on and in electrical contact with said second layer of semiconductor material.

Claim 20

The semiconductor device according to claim 14 wherein said second layer of semiconductor material is coextensive with said first layer and wherein both of said ohmic contact means are on and in electrical contact with said second layer of semiconductor material.

Claim 21

The semiconductor device according to claim 14 further comprising a second region of said second layer of semiconductor material substantially identical to said first region of semiconductor material on said first layer of semiconductor material; and wherein said second ohmic contact is on and in electrical communication with to said second region of said second layer of semiconductor material.

Claim 22

A semiconductor device according to any of claims 14 through 18 wherein said layer in said regions of Hg 1-x Cd x Te and Hg 1-y Cd y Te are formed by epitaxial growth.

Claim 23

A semiconductor device according to claim 19 wherein said epitaxial growth is liquid phase epitaxy.

Claim 24

The semiconductor device according to claim 19 wherein said epitaxial growth is vapor phase epitaxy.

Claim 25

A semiconductor device according to any of claims 14 through 18 wherein said layer of Hg 1-x Cd x Te has a thickness from about 5×10 -4 cm to about 15×10 -4 cm and said layer of Hg 1-y Cd y Te has a thickness from about 10 -4 cm to 10 -3 cm.