The Optics Laboratory
Group of Hans Hallen, Physics Department, North Carolina State University

Quantification

The recombination rate can be related to the measurements that vary the visible light chopping frequency, as indicated on the imaging page. Plots of the relative IR signal change vs. the visible light switching frequency are shown for two different samples. The lifetime can be quantitatively measured from the 'knee' position.

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The samples with data as triangles and circles have effective lifetimes estimated from the knee of 20 µsec and 1.6 msec, respectively.

 

We have compared the lifetime measured as the inverse of the knee frequency (a local measurement) to the average lifetime measurement for the entire sample using an independent (laser/microwave) method. We find agreement between our local method and the large-area technique. For the samples with lifetimes given above in the near-field, the far-field measurement gave 13.6 µsec and 1.62 msec, respectively, showing the accuracy of the technique over orders of magnitude lifetime range.

  •  More info is in the papers.

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