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Title: Photodetector having high speed and sensitivity

Abstract

The present invention provides a photodetector having an advantageous combination of sensitivity and speed; it has a high sensitivity while retaining high speed. In a preferred embodiment, visible light is detected, but in some embodiments, x-rays can be detected, and in other embodiments infrared can be detected. The present invention comprises a photodetector having an active layer, and a recombination layer. The active layer has a surface exposed to light to be detected, and comprises a semiconductor, having a bandgap graded so that carriers formed due to interaction of the active layer with the incident radiation tend to be swept away from the exposed surface. The graded semiconductor material in the active layer preferably comprises Al.sub.1-x Ga.sub.x As. An additional sub-layer of graded In.sub.1-y Ga.sub.y As may be included between the Al.sub.1-x Ga.sub.x As layer and the recombination layer. The recombination layer comprises a semiconductor material having a short recombination time such as a defective GaAs layer grown in a low temperature process. The recombination layer is positioned adjacent to the active layer so that carriers from the active layer tend to be swept into the recombination layer. In an embodiment, the photodetector may comprise one or more additional layersmore » stacked below the active and recombination layers. These additional layers may include another active layer and another recombination layer to absorb radiation not absorbed while passing through the first layers. A photodetector having a stacked configuration may have enhanced sensitivity and responsiveness at selected wavelengths such as infrared.« less

Inventors:
 [1];  [2]
  1. Martinez, CA
  2. (Danville, CA)
Issue Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
OSTI Identifier:
867998
Patent Number(s):
5051804
Assignee:
United States of America as represented by United States (Washington, DC)
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
photodetector; speed; sensitivity; provides; advantageous; combination; retaining; preferred; embodiment; visible; light; detected; embodiments; x-rays; infrared; comprises; active; layer; recombination; surface; exposed; semiconductor; bandgap; graded; carriers; formed; due; interaction; incident; radiation; tend; swept; material; preferably; 1-x; additional; sub-layer; 1-y; included; time; defective; gaas; grown; temperature; process; positioned; adjacent; comprise; layers; stacked; below; absorb; absorbed; passing; configuration; enhanced; responsiveness; selected; wavelengths; stacked configuration; enhanced sensitivity; incident radiation; additional layers; exposed surface; selected wavelength; layer comprises; semiconductor material; preferred embodiment; visible light; preferably comprises; positioned adjacent; active layer; temperature process; gaas layer; absorb radiation; carriers formed; selected wavelengths; selected wave; additional layer; preferably comprise; layer grown; /257/

Citation Formats

Morse, Jeffrey D, and Mariella, Jr., Raymond P. Photodetector having high speed and sensitivity. United States: N. p., 1991. Web.
Morse, Jeffrey D, & Mariella, Jr., Raymond P. Photodetector having high speed and sensitivity. United States.
Morse, Jeffrey D, and Mariella, Jr., Raymond P. Tue . "Photodetector having high speed and sensitivity". United States. https://www.osti.gov/servlets/purl/867998.
@article{osti_867998,
title = {Photodetector having high speed and sensitivity},
author = {Morse, Jeffrey D and Mariella, Jr., Raymond P.},
abstractNote = {The present invention provides a photodetector having an advantageous combination of sensitivity and speed; it has a high sensitivity while retaining high speed. In a preferred embodiment, visible light is detected, but in some embodiments, x-rays can be detected, and in other embodiments infrared can be detected. The present invention comprises a photodetector having an active layer, and a recombination layer. The active layer has a surface exposed to light to be detected, and comprises a semiconductor, having a bandgap graded so that carriers formed due to interaction of the active layer with the incident radiation tend to be swept away from the exposed surface. The graded semiconductor material in the active layer preferably comprises Al.sub.1-x Ga.sub.x As. An additional sub-layer of graded In.sub.1-y Ga.sub.y As may be included between the Al.sub.1-x Ga.sub.x As layer and the recombination layer. The recombination layer comprises a semiconductor material having a short recombination time such as a defective GaAs layer grown in a low temperature process. The recombination layer is positioned adjacent to the active layer so that carriers from the active layer tend to be swept into the recombination layer. In an embodiment, the photodetector may comprise one or more additional layers stacked below the active and recombination layers. These additional layers may include another active layer and another recombination layer to absorb radiation not absorbed while passing through the first layers. A photodetector having a stacked configuration may have enhanced sensitivity and responsiveness at selected wavelengths such as infrared.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1991},
month = {1}
}

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