| Autor: |
Aivaliotis, P., Zibik, E. A., Wilson, L. R., Cockburn, J. W., Hopkinson, M., Vinh, N. Q. |
| Předmět: |
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| Zdroj: |
Applied Physics Letters; 1/14/2008, Vol. 92 Issue 2, p023501, 3p, 4 Graphs |
| Abstrakt: |
Two photon absorption processes in InAs/In01.5Ga0.85As/GaAs quantum dot-in-a-well photodetectors are studied using free electron laser excitation. Two photon induced, normal incidence photocurrent, observed in the range of 20–30 μm, arises from sequential near-resonant two-step transitions involving electron ground to first excited states in the dot, to quantum well final states. We find a two photon absorption coefficient of β∼1×107 cm/GW at 26.5 μm (47 meV) and 0.8 V applied bias. Second-order autocorrelation measurements exhibit two characteristic time constants of ∼3 and ∼40 ps. The latter is associated with the intermediate state electron lifetime, whereas the short decay is explained by the involvement of acoustic phonon assisted transitions. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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