Authors: Glosser, R; Al-Arfaj, Esam; Alavi, Kambiz; Beam III, E A.

Source: Canadian Journal of Physics, Volume 83, Number 10, October 2005 , pp. 1029-1034(6)

Publisher: NRC Research Press

Abstract:

We have observed the behavior of photoreflectance (PR) spectra from a set of a molecular-beam-epitaxy-grown heterostructures as a function of the modulation duty cycle. This was done over a range of frequencies extending from 10–1000 Hz. By varying the duty cycle of the pump beam at different frequencies, we are able to find the duty cycle that gave the largest amplitude. While standard PR techniques use a 50% duty cycle, we have found that at low frequencies (10–30 Hz) the optimal value is between 30–40% in these particular sets of experiments resulting in as much as a 33% increase in amplitude. The change in the optimal values of the duty cycle from sample to sample was qualitatively correlated to the deep levels sample. PACS Nos.: 78.20.Ci, 78.40., 78.40.Fy

Nous avons étudié le spectre du facteur de réflexion (PR) sur un ensemble d'hétérostructures, développées par faisceau moléculaire épitaxial (MBE), en fonction de la modulation du cycle d'opération. Ceci a été complété sur un domaine de fréquences allant de 10 à 1000 Hz. En variant la fréquence du cycle d'opération du faisceau pompe, nous sommes capables de trouver le cycle d'opération qui donne la plus grande amplitude. Alors que les techniques PR usuelles utilisent un cycle d'opération de 50 %, nous trouvons qu'à basse fréquence [10–30 Hz] la valeur optimale est entre 30 % et 40 % pour ces ensembles particuliers d'expériences, résultant en une augmentation allant jusqu'à 33 % en amplitude. La variation du cycle d'opération optimal d'un échantillon à l'autre était qualitativement correlé à la profondeur des niveaux.[Traduit par la rédaction]

Document Type: Research article

Publication date: 2005-10-01

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