Intra-valence-band mixing in strain-compensated SiGe quantum wells

Article

关键词: INTERSUBBAND ABSORPTION;    TEMPERATURE;    HOLES;   

DOI  :  10.1103/PhysRevB.72.153315

来源: SCIE

【 摘 要 】

We explore the midinfrared absorption of strain-compensated p-Si0.2Ge0.8/Si quantum wells for various well thicknesses and temperatures. Owing to the large band offset due to the large bi-axial strain contrast between the wells and barriers, the intersubband transitions energies from the ground state to the excited heavy hole (HH), light hole (LH), and split-off (SO) hole states up to similar to 0.5 eV are resolved. When HH2 is within similar to 30 meV of LH1 or SO1 a partial transfer of the HH1-HH2 oscillator strength to the HH1-LH1 or HH1-SO1 transitions is observed, which is otherwise forbidden for light polarized perpendicular to the plane of the wells. This is a clear sign of mixing between the HH and LH or SO states. A large temperature induced broadening of HH1-HH2 transition peak is observed for narrow wells indicating nonparabolic dispersion of the HH2 states due to the mixing with the LH/SO continuum. We found that the observations are in good agreement with the six-band k center dot p theory. A possible role of many-body effects in the temperature-induced negative peak shift is discussed.

【 授权许可】

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