Bormann, I. and Brunner, Konrad and Hackenbuchner, S. and Abstreiter, Gerhard and Schmult, Stefan and Wegscheider, Werner
Nonradiative relaxation times in diagonal transition Si/SiGe quantum cascade structures.
Applied Physics Letters 83 (26), pp. 5371-5373.
Here, we explore experimentally and theoretically the possibility to prolong the upper hole state nonradiative lifetime of Si/SiGe quantum cascade (QC) structures by using a spatially indirect diagonal transition between two SiGe quantum well ground states. With the recent observation of well resolved midinfrared electroluminescence from heavy hole intersubband transitions in Si/SiGe valence-band QC structures, a Si-based QC laser seems no longer to be out of reach. A long carrier lifetime and maybe population inversion, however, appear to be impossible for structure designs with a vertical intersubband transition studied so far. This is due to the nonresonant behavior of deformation potential scattering dominant in unipolar SiGe. We report on calculations of the band structure using a six-band k·p model and of hole deformation potential scattering that predict significantly increased nonradiative lifetimes for large barrier thickness, reaching about 20 ps for 35 Å Si barrier layer width. Electroluminesence measurements of a series of QC structures with varied barrier width reveal comparable efficiencies and the deduced lifetimes confirm our model calculations.
|Date:||29 December 2003|
|Institutions:|| Physics > Institute of Experimental and Applied Physics > Retired Professors > Group Werner Wegscheider|
|78.60.Fi; 78.67.De; 73.21.Fg; ||PACS|
|Keywords:||Ge-Si alloys, semiconductor materials, silicon, elemental semiconductors, semiconductor quantum wells, nonradiative transitions, electroluminescence, k.p calculations, carrier lifetime, carrier relaxation time, population inversion |
|Subjects:||500 Science > 530 Physics|
|Created at the University of Regensburg:||Unknown|
|Deposited On:||15 Dec 2009 08:51|
|Last Modified:||20 Jul 2011 22:12|