Abstract
Radiative recombination and relevant dynamic effects are studied in SiGe-based shallow quantum confinement systems where an inherently small barrier height controls the optoelectronic properties. Dynamic localization is demonstrated in a double quantum well carrying a pair of quantum wells with differential potential depths, leading to a remarkable observation of highly efficient “classical” carrier blocking due to an attractive potential as opposed to conventional repulsive potential blocking utilizing the wave character of carriers. The underlying mechanism is controlled by hole re-emission with increasing temperature. In addition, it is shown that shallow-confined electrons are susceptible to electric fields, thereby masking the Stark shifts in type-I quantum wells at low field regime and reducing decay lifetimes due to exciton field ionization. These are shown to arise from extended wavefunction of electrons assuming three-dimensional character. Furthermore, modulation of exciton luminescence due to excess background charges is shown to address the importance of screening in a high pump condition.
Published Version
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