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(a) Schematic of the sample structure and the optical path for the PL measurements. (b) High-resolution transmission electron micrograph of a QD stack viewed along the axis.
Low-temperature and room temperature PL spectra of a five-layers QDSL as a function of external bias (in steps of ).
(a) Evolution of the PL intensity and the photocurrent with bias. (b) Sketch of the band diagram of a three-layer structure based on simulations illustrating the current transport due to tunneling of photoexcited carriers. Negative external bias leads to a reduction of the effective tunneling barrier thickness due to the displacement of electron and hole wave functions.
(a) PL spectra in pure and atmosphere at a bias voltage of . The inset shows the response of the peak intensity to two pulses of in synthetic air as carrier gas. (b) Response of the PL intensity to introduction of 10% hydrogen in a nitrogen atmosphere for samples with one and five QD layers. The PL intensity was recorded at a fixed detection wavelength near the emission maximum (due to a different size of the QDs the maximum of the PL emission is located at an energy of for the single QD layer).
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