Photodiode

• US 4,999,694 A
• Filed: 08/18/1989
• Issued: 03/12/1991
• Est. Priority Date: 08/18/1989
• Status: Expired due to Term

• Current Assignee: American Telephone & Telegraph Company (AT&T, Inc.), Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Original Assignee: AT&T, Inc.
• Inventors: Austin, Richard F., Sulhoff, James W., Feldman, Robert D., Zyskind, John L.
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): Sotomayor, John B.
• Application Number:
  US07/395,922
• Time in Patent Office: 571 Days
• Field of Search: 357/30 B, 357/30 C, 357/15, 357/61, 357/16, 437/126, 437/176, 148/DIG. 39
• US Class Current: 257/188
• CPC Class Codes: H01L 31/02966 including ternary compounds, e.g. HgCdTe
• CPC Class Codes: H01L 31/101 Devices sensitive to infrared, visible or ultraviolet radiation
• CPC Class Codes: H01L 31/108 the potential barrier being of the Schottky type
• CPC Class Codes: Y02E 10/547 Monocrystalline silicon PV cells

Abstract

In this invention, there is disclosed a new photodiode which comprises a semimetal/semiconductor junction. Distortion of the bands associated with this type of junction result in current flow when an electron hole pair is formed by, for example, a photon impinging upon the junction. The photodiode operates in the photovoltaic mode. However, rather than relying on impurity doping to fabricate a p-n junction, the semimetallic nature of HgTe and its large conduction band offsets with Hg_1-x Cd_x Te are used to create a rectifying Schottky like structure.

Claims

1. A photovoltaic detector with a planar structure having a first buffer layer of semi insulating ZnTe,

a second buffer layer of semi insulating CdTe located above said first buffer layer,

an substrate of GaAs located below said first buffer layer, p1 an epitaxial semiconductor semimetal Schottky type of photodiode having an isotype heterojunction located above said second buffer layer, and

first and second contacts coupled to said epitaxial semiconductor semimetal Schottly type of photodiode to provide a diode.

2. The photovoltaic detector of claim 1

wherein said epitaxial semiconductor semimetal Schottky type of photodiode comprises a layer of HgTe grown by molecular beam epitaxy without intentional doping located above said second buffer layer, a layer of Hg_1-x Cd_x Te grown by molecular beam epitaxy without intentional doping where x is greater than 0 but less than 1 located above a portion of said layer of HgTe,

said layer of HgTe forming an isotype heterojunction with said layer of Hg_1-x Cd_x Te

a first contact located above said layer Hg₁ -x Cd_x Te;

and a second contact located above said layer of HgTe.