Phys. Rev. Lett. 102, 147401 (2009) [4 pages]Continuous Voltage Tunability of Intersubband Relaxation Times in Coupled SiGe Quantum Well Structures Using Ultrafast SpectroscopyReceived 25 September 2008; published 6 April 2009 We demonstrate continuous voltage control of the nonradiative transition lifetime in semiconductor heterostructures. The results were obtained by picosecond time-resolved experiments on biased SiGe valence band quantum well structures using a free electron laser. By varying the applied voltage, the intersubband hole relaxation times for quantum well structures were varied by a factor of 2 as the wave functions and their overlaps were tuned. The range of magnitudes for the lifetime indicates a possible route to silicon-based quantum cascade lasers. © 2009 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevLett.102.147401
DOI:
10.1103/PhysRevLett.102.147401
PACS:
78.67.De, 73.21.−b, 73.50.Pz, 78.47.−p
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