Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
203 words
An infrared photodetector comprising: (a) a substrate of a semiconductor material; (b) first contact means for applying an electrical potential to a back side of said substrate; (c) at least four high resistivity layers of said semiconductor material disposed on a top surface of said substrate, said layers of said first material being of substantially equal thickness and being doped a conductive type with a doping concentration therein sufficiently low as to not include conducting donor bands and being depleted of electrons; (d) at least three impurity-band layers of said semiconductor material disposed on said layers of said first material, said layers of said second material being of substantially equal thickness and being doped said conductivity type with a doping concentration therein sufficiently high to include donor bands which can release electrons upon impingement by infrared photons of energy hν greater than an energy gap ε; (e) means for applying an electrical field across said substrate and said plurality of layers; (f) a layer of a transparent contact material disposed on a top one of said layers of said first material; and (g) second contact means for applying an electrical potential to a top side of said layer of a transparent contact material.
Claim 2
Dependent Claim
203 words
An infrared photodetector comprising: (a) a substrate of a semiconductor material; (b) first contact means for applying an electrical potential to a back side of said substrate; (c) at least four high resistivity layers of said semiconductor material disposed on a top surface of said substrate, said layers of said first material being of substantially equal thickness and being doped a conductive type with a doping concentration therein sufficiently low as to not include conducting donor bands and being depleted of electrons; (d) at least three impurity-band layers of said semiconductor material disposed on said layers of said first material, said layers of said second material being of substantially equal thickness and being doped said conductivity type with a doping concentration therein sufficiently high to include donor bands which can release electrons upon impingement by infrared photons of energy hν greater than an energy gap ε; (e) means for applying an electrical field across said substrate and said plurality of layers; (f) a layer of a transparent contact material disposed on a top one of said layers of said first material; and (g) second contact means for applying an electrical potential to a top side of said layer of a transparent contact material.
Claim 3
Dependent Claim
52 words
The infrared photodetector of claim 1 wherein: (a) said substrate is degenerate germanium; (b) said impurity-band layers are layers of germanium doped to approximately the low 10 16 cm -3 range; and, (c) said high resistivity layers are layers of germanium doped to a maximum of approximately 10 15 cm -3 .
Claim 4
Dependent Claim
50 words
The infrared photodetector of claim 1 wherein: (a) said substrate is silicon; (b) said impurity-band layers are layers of silicon doped to approximately the 10 17 cm -3 range; and, (c) said high resistivity layers are layers of silicon doped to a maximum of approximately 10 15 cm -3 .
Claim 5
Dependent Claim
39 words
The infrared photodetector of claim 2 wherein: (a) said substrate is degenerate n-type (n ++ ) germanium; (b) said impurity-band layers are n + layers of germanium; and, (c) said high resistivity layers are n - layers of germanium.
Claim 6
Dependent Claim
23 words
The infrared photodetectors of claim 1 wherein: said impurity-band layers have a thickness less than a conduction-electron diffusion length in said semi-conductor material.
Claim 7
Dependent Claim
19 words
The infrared photodetector of claim 5 wherein: said impurity-band layers are in the range of 0.1-1.0 micron in thickness.
Claim 8
Dependent Claim
32 words
The infrared photodetector of claim 1 wherein: the number of said impurity-band layers is such that a flux of infrared photons passing therethrough will be substantially totally absorbed by said impurity-band layers.
Claim 9
Dependent Claim
55 words
The infrared photodetector of claim 1 wherein: the thickness of each of said high resistivity layers is such compared to a voltage applied to said first and second contact means that a voltage drop in each of said high resistivity layers controls the occurrence of impact ionization in said impurity-band layers to a desired level.
Claim 10
Dependent Claim
40 words
The infrared photodetector of claim 1 wherein: the doping level in each of said impurity-band layers is different from the doping level in others of said impurity-band layers so as to achieve a desired spectral response across the entire photodetector.
Claim 11
Dependent Claim
42 words
The infrared photodetector of claim 1 wherein: the doping level in each of said impurity-band layers is varied so as to be more concentrated in a center portion of each said layers so as to increase the breakdown level of the photodetector.