Quantum cascade detectors (QCD) are photovoltaic mid-infrared based on intersubband transitions. Owing to the sub-picosecond carrier transport between subbands and absence of a bias voltage, QCDs ideally suited for high-speed room temperature operation. Here, we demonstrate design, fabrication, characterization 4.3 µm wavelength optimized large electrical bandwidth. The detector signal is extra...

Modulation-doped semiconductor nanostructures exhibit extraordinary electrical and optical properties that are quantum mechanical in nature. The heart of such structures lies in the heterojunction of two epitaxially grown semiconductors with different band gaps. Quantum confinement in this heterojunction is a phenomenon that leads to the quantization of the conduction and the valence band into ...

S. G. Carter,1,* V. Ciulin,1,† M. Hanson,2 A. S. Huntington,2,‡ C. S. Wang,3 A. C. Gossard,2,3 L. A. Coldren,2,3 and M. S. Sherwin1 1Physics Department and iQUEST, University of California, Santa Barbara, California 93106, USA 2Materials Department, University of California, Santa Barbara, California 93106, USA 3Electrical and Computer Engineering Department, University of California, Santa Bar...

We report on the use of InAlAs linearly graded buffer layers for improving the performance of InyGa12yAs (y.0.42)/AlGaAs intersubband transition ~ISBT! superlattice structures grown on GaAs substrates by molecular beam epitaxy. Linearly graded InAlAs buffer layers give better optical confinement in the active superlattice region, similar intersubband transition linewidths, and comparable surfac...

Monte Carlo simulation of carrier dynamics and far-infrared absorption was performed to test the importance of electron-electron interaction in selectively doped multi-layer p-Ge laser at high doping concentration. The laser design exploits the known widely tunable mechanism of THz amplification on inter-sub-band transitions in p-Ge, but with spatial separation of carrier accumulation and relax...

We present a microscopic many-particle theory for the dephasing of coherent intersubband excitations in semiconductor quantum wells including carrier-carrier and carrier-phonon scattering and light propagation effects. The contributions of many-particle processes are nonadditive and thus cannot be treated separately. It is shown that due to nondiagonal correlation contributions, scattering rate...