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|Title:||Photoluminescence from ultrathin Ge-rich multi-quantum wells observed up to room-temperature: experiments and modeling|
Fischer, I. A.
Cerqueira, M. F.
|Publisher:||American Physical Society|
|Journal:||Physical Review B|
|Citation:||Physical Review B 94, pp. 245304 (2016)|
|Abstract(s):||Employing a low-temperature growth-mode, we fabricated ultrathin Si1-xGex/Si multiple quantum well (QW) structures with a well thickness of less than 1.5 nm and a Ge concentration above 60 % directly on a Si substrate. We identified an unusual temperature-dependent blueshift of the photoluminescence (PL) and an exceptionally low thermal quenching. We find that this behavior is related to the relative intensities of the no-phonon (NP) peak and a phonon-assisted replica that are the main contributors to the total PL signal. In order to investigate these aspects in more detail, we developed a strategy to calculate the PL spectrum employing a self-consistent multi-valley effective mass model in combination with second-order perturbation theory. According to our investigation, we find that while the phonon-assisted feature decreases with temperature, the NP feature shows a strong increase in the recombination rate. Besides leading to the observed robustness against thermal quenching, this causes the observed blueshift of the total PL signal.|
|Appears in Collections:||CDF - CEP - Artigos/Papers (with refereeing)|
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