Electronic Resource
Woodbury, NY
:
American Institute of Physics (AIP)
Applied Physics Letters
69 (1996), S. 3069-3071
ISSN:
1077-3118
Source:
AIP Digital Archive
Topics:
Physics
Notes:
We have investigated the saturation of intersubband absorption and the intersubband relaxation time in the valence band of Si/SiGe quantum wells. The quantum wells consist of 3 nm thick p-doped Si0.8Ge0.2 layers separated by 20 nm thick silicon barriers. At room temperature, these quantum wells exhibit intersubband absorption in p polarization (component of the electric field parallel to the growth axis), which peaks around 130 meV (≈10 μm). The saturation of intersubband absorption has been investigated using a picosecond free electron laser by two different techniques. The intersubband absorption is first analyzed as a function of the pump intensity. The saturation is found to occur around 90 MW/cm2, which yields a characteristic lifetime T1≈0.7 ps. In a second set of experiments, the lifetime is determined by time-resolved pump and probe experiments in cross polarization. The intersubband transition is pumped in p polarization and the saturated absorption is probed with a delayed beam in s polarization. An intersubband lifetime ≈0.4 ps is deduced by this technique. The saturation behavior is analyzed in terms of an inhomogeneously broadened two-level system. © 1996 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.116842
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