| Résumé | The effects of optical interference in quantum-well infrared photodetectors (QWIPs) caused by reflection of radiation from the metal contact are investigated. It is shown that interference leads to strong deterioration of QWIP characteristics (responsivity, noise, and noise equivalent power (NEP)) if signal photocurrent is larger than the dark current or background current. This is caused by the nonuniform distribution of the photogeneration rate, electric field, and all other microscopic physical quantities. As a result, the photocurrent gain and photoionization efficiency are decreased, while the noise gain is increased with respect to their values for uniform excitation. Several puzzling experimental effects - a strong increase of the QWIP NEP for high-power heterodyne operation and temperature dependence of QWIP responsivity - can be explained by the model described above. |
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