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Full-Text Articles in Physics
Carrier Dynamics Of Terahertz Emission Based On Strained Sige/Si Single Quantum Well, K. M. Hung, J.-Y. Kuo, C. C. Hong, Greg Sun, R. A. Soref
Carrier Dynamics Of Terahertz Emission Based On Strained Sige/Si Single Quantum Well, K. M. Hung, J.-Y. Kuo, C. C. Hong, Greg Sun, R. A. Soref
Physics Faculty Publications
We report analysis of the carrier distribution during terahertz emission process with carrier–phonon interaction based on p-doped strained SiGe/Si single quantum-well. The results of this analysis show that a considerable number of carriers can penetrate the phonon wall to become “hot” carriers on an approximately picosecond timescale. These hot carriers relax after the removal of the applied voltage, generating a “second” emission in the measurement. This investigation provides an understanding of the carrier dynamics of terahertz emission and has an implication for the design of semiconductor terahertz emitters.
Radiation Emission From Wrinkled Sige/Sige Nanostructure, A. I. Fedorchenko, H. H. Cheng, Greg Sun, R. A. Soref
Radiation Emission From Wrinkled Sige/Sige Nanostructure, A. I. Fedorchenko, H. H. Cheng, Greg Sun, R. A. Soref
Physics Faculty Publications
Semiconductor optical emitters radiate light via band-to-band optical transitions. Here, a different mechanism of radiation emission, which is not related to the energy band of the materials, is proposed. In the case of carriers traveling along a sinusoidal trajectory through a wrinkled nanostructure, radiation was emitted via changes in their velocity in a manner analogous to synchrotron radiation. The radiated frequency of wrinkled SiGe/SiGe nanostructure was found to cover a wide spectrum with radiation power levels of the order of submilliwatts. Thus, this nanostructure can be used as a Si-based optical emitter and it will enable the integration of optoelectronic …
Electron Tunneling In A Strained N-Type Si1−Xgex/Si/Si1−Xgex Double-Barrier Structure, K. M. Hung, T. H. Cheng, W. P. Huang, K. Y. Wang, H. H. Cheng, Greg Sun, R. A. Soref
Electron Tunneling In A Strained N-Type Si1−Xgex/Si/Si1−Xgex Double-Barrier Structure, K. M. Hung, T. H. Cheng, W. P. Huang, K. Y. Wang, H. H. Cheng, Greg Sun, R. A. Soref
Physics Faculty Publications
We report electrical measurements on an n-type Si1−xGex/Si/Si1−xGex double-barrier structure grown on a partially relaxed Si1−yGey buffer layer. Resonance tunneling of Δ4band electrons is demonstrated. This is attributed to the strain splitting in the SiGe buffer layer where the Δ4 band is lowest in energy at the electrode. Since the Δ4 band electrons have a much lighter effective mass along the direction of tunneling current in comparison with that of the Δ2 band electrons, this work presents an advantage over those …
Terahertz Gain In A Sige/Si Quantum Staircase Utilizing The Heavy-Hole Inverted Effective Mass, Richard A. Soref, Greg Sun
Terahertz Gain In A Sige/Si Quantum Staircase Utilizing The Heavy-Hole Inverted Effective Mass, Richard A. Soref, Greg Sun
Physics Faculty Publications
Modeling and design studies show that a strain-balanced Si1−xGex/Si superlattice onSi1−yGey-buffered Si can be engineered to give an inverted effective mass HH2 subband adjacent to HH1, thereby enabling a 77 K edge-emitting electrically pumped p–i–pquantum staircase laser for THz emission at energies below the 37 meV Ge–Ge optical phonon energy. Analysis of hole-phonon scattering, lifetimes, matrix elements, and hole populations indicates that a gain of 450 cm−1 will be feasible at f = 7.3 THz during 1.7 kA/cm2 current injection.
Sige/Si Thz Laser Based On Transitions Between Inverted Mass Light-Hole And Heavy-Hole Subbands, L. Friedman, Greg Sun, Richard A. Soref
Sige/Si Thz Laser Based On Transitions Between Inverted Mass Light-Hole And Heavy-Hole Subbands, L. Friedman, Greg Sun, Richard A. Soref
Physics Faculty Publications
We have investigated a SiGe/Si quantum-well laser based on transitions between the light-hole and heavy-hole subbands. The lasing occurs in the region of k space where the dispersion of ground-state light-hole subband is so nonparabolic that its effective mass is inverted. This kind of lasing mechanism makes total population inversion between the two subbands unnecessary. The laser structure can be electrically pumped through tunneling in a quantum cascade scheme. Optical gain as high as 172/cm at the wavelength of 50 μm can be achieved at the temperature of liquid nitrogen, even when the population of the upper laser subband is …