## Abstract

Calculations of the quantum efficiency and detectivity of an infrared detector based on photoemission from a quantum well are presented. The detector is most efficient when a resonant-extended state exists near the top of the well. The quantum efficiency also increases with increasing electron density. However, due to screening, the absorption peaks at a higher energy than the difference of the energies of the resonant-extended and the bound states by an amount which is proportional to the carrier density in the well. This causes the detectivity (D*) to have a maximum with respect to electron density. We have estimated the dark current and found that, for a GaAs quantum-well detector designed for 10-μm operation, the optimal electron density was 2×10^{11} cm^{-2} at 77 K. We have also performed calculations for a quantum-well detector for which the light coupling has been enhanced by incorporating a diffraction grating into the detector. For the stated electron density, we find a D* of 2.8×10^{11} cm Hz^{1/2}/W and a quantum efficiency of 23%. If the electron density is raised to 8×10^{11} cm^{-2}, the quantum efficiency rises to 61%, but D* falls to 1.9×10^{1} ^{0} cm Hz^{1/2}/W.

Original language | English (US) |
---|---|

Pages (from-to) | 5149-5153 |

Number of pages | 5 |

Journal | Journal of Applied Physics |

Volume | 63 |

Issue number | 10 |

DOIs | |

State | Published - Dec 1 1988 |

## All Science Journal Classification (ASJC) codes

- Physics and Astronomy(all)