Luminescence study on interdiffusion in strained Si1−xGex/Si single quantum wells grown by molecular beam epitaxy

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Abstract
Optical investigation of interdiffusion at Si1−xGex/Si heterointerfaces has been performed for the first time in strained Si1−xGex/Si single quantum wells (SQWs). Photoluminescence (PL) peak energy blue shift of up to 22 meV due to interdiffusion‐induced potential profile modulation was observed after annealing in vacuum. The diffusion coefficients obtained were found to closely follow an Arrhenius behavior with an activation energy of 2.47±0.4 eV. Dramatic increase in the integrated PL intensity was observed in the annealed samples, as a result of the elimination of effective nonradiative centers. Strain relaxation was hardly observed even after 900 °C annealing, indicating the unprecedented structural stability of SQWs in contrast to rather vulnerable thick alloy layers. Anomalous peak red shift, probably due to surface oxidation, was observed by annealing in N2 ambient.