科研之友
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摘要
The design of terahertz quantum cascade lasers based on electronic intersubband transitions in Ge/SiGe quantum wells is investigated. A detailed theoretical model of the conduction-band lineup of these heterostructures is first presented and used to show that large quantum confinement in the L valleys can be obtained with properly selected layer compositions and thicknesses. Computation of the key laser design parameters is then discussed, including the important role played by the L-valley ellipsoidal constant-energy surfaces. Finally, the main design issues specific to this material system and its potential for high-performance operation are illustrated by means of two exemplary structures, designed for emission near 50 and 25 mu m.
- 出版日期2007-11-1
