PHOTOCURRENT ABSORPTION SPECTROSCOPIC STUDY OF Si0.6Ge0.4/Si QUANTUM WELLS

2006 ◽  
Vol 20 (02) ◽  
pp. 133-140
Author(s):  
SHIHUA HUANG ◽  
FENGMIN WU ◽  
JI LIN ◽  
FANG LU
Keyword(s):  
Energy Level ◽  
Spectroscopic Study ◽  
Quantum Wells ◽  
Valence Band ◽  
Ground State ◽  
State Energy ◽  
Energy Levels ◽  
Absorption Coefficients ◽  
Discrete Energy ◽  
Discrete Energy Level

Absorption spectra of Si 0.6 Ge 0.4/ Si quantum wells are characterized by photocurrent measurements. The absorption coefficients of two different transitions, namely the transition between the Si band states and the discrete energy level in quantum wells, and the interlevel transition in quantum wells are deduced. They are directly proportional to (ℏω-ΔE)3/2 and δ(ℏω-Eeh), respectively. The valence band offsets of Si 0.6 Ge 0.4/ Si interface are 297 meV. The ground state energy levels in valence band and conduction band Si 0.6 Ge 0.4/ Si quantum wells are 37 meV and 23 meV, respectively.

scholarly journals Electron Population Dynamics in Optically Pumped Asymmetric Coupled Ge/SiGe Quantum Wells: Experiment and Models

Photonics ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 2 ◽  
Author(s):  
Chiara Ciano ◽  
Michele Virgilio ◽  
Luigi Bagolini ◽  
Leonetta Baldassarre ◽  
Andrea Rossetti ◽  
...  
Keyword(s):  
Energy Level ◽  
Quantum Wells ◽  
Quantum Cascade Lasers ◽  
Balance Model ◽  
Optically Pumped ◽  
Discrete Energy ◽  
Discrete Energy Level ◽  
Saturation Intensity ◽  
Sige Quantum Wells ◽  
Scattering Rates

n-type doped Ge quantum wells with SiGe barriers represent a promising heterostructure system for the development of radiation emitters in the terahertz range such as electrically pumped quantum cascade lasers and optically pumped quantum fountain lasers. The nonpolar lattice of Ge and SiGe provides electron–phonon scattering rates that are one order of magnitude lower than polar GaAs. We have developed a self-consistent numerical energy-balance model based on a rate equation approach which includes inelastic and elastic inter- and intra-subband scattering events and takes into account a realistic two-dimensional electron gas distribution in all the subband states of the Ge/SiGe quantum wells by considering subband-dependent electronic temperatures and chemical potentials. This full-subband model is compared here to the standard discrete-energy-level model, in which the material parameters are limited to few input values (scattering rates and radiative cross sections). To provide an experimental case study, we have epitaxially grown samples consisting of two asymmetric coupled quantum wells forming a three-level system, which we optically pump with a free electron laser. The benchmark quantity selected for model testing purposes is the saturation intensity at the 1→3 intersubband transition. The numerical quantum model prediction is in reasonable agreement with the experiments and therefore outperforms the discrete-energy-level analytical model, of which the prediction of the saturation intensity is off by a factor 3.

scholarly journals GROUND STATE ENERGY LEVEL OF Si-BASE QUANTUM WELLS DETECTED BY ADMITTANCE SPECTROSCOPY

1998 ◽  
Vol 47 (7) ◽  
pp. 1171
Author(s):  
LIN FENG ◽  
SHENG CHI ◽  
KE LIAN ◽  
ZHU JIAN-HONG ◽  
GONG DA-WEI ◽  
...  
Keyword(s):  
Energy Level ◽  
Quantum Wells ◽  
Ground State Energy ◽  
Ground State ◽  
State Energy ◽  
Admittance Spectroscopy

The influences of parabolic potential and magnetism on strongly coupled polaron characteristics within asymmetric Gaussian quantum wells

2021 ◽  
Author(s):  
Saren Gaowa ◽  
Yan-Bo Geng ◽  
Zhao-Hua Ding ◽  
Jing-Lin Xiao
Keyword(s):  
Magnetic Field ◽  
Quantum Wells ◽  
Barrier Height ◽  
Ground State Energy ◽  
Ground State ◽  
State Energy ◽  
Cyclotron Frequency ◽  
Strongly Coupled ◽  
Parabolic Potential ◽  
Do So

In this research, the effects of magnetism and parabolic potential on strongly coupled polaron characteristics within asymmetric Gaussian quantum wells (AGQWs) were investigated. To do so, the following six parameters were studied, temperature, AGQW barrier height, Gaussian confinement potential (GCP) width, confinement strengths along the directions of [Formula: see text] and [Formula: see text], as well as magnetic field cyclotron frequency. The relationships among frequency oscillation, AGQW parameters and polaron ground state energy in RbCl crystal were studied based on linear combination operator and Lee–Low–Pines unitary transformation. It was concluded that ground state energy absolute value was decreased by increasing GCP width and temperature, and increased with the increase of confinement strength along [Formula: see text] and [Formula: see text] directions, cyclotron frequency of magnetic field and barrier height of AGQW. It was also found that vibrational frequency was increased by enhancing confinement strengths along the directions of [Formula: see text] and [Formula: see text], magnetic field cyclotron frequencies, barrier height AGQW and temperature and decreased with the increase of GCP width.

Carrier Hopping and Relaxation in InAs/GaAs Quantum Dot Heterostructures

2014 ◽  
Vol 875-877 ◽  
pp. 9-13
Author(s):  
Ya Fen Wu ◽  
Jiunn Chyi Lee
Keyword(s):  
Energy Level ◽  
Quantum Dot ◽  
Temperature Dependence ◽  
Thermal Emission ◽  
Carrier Dynamics ◽  
Photoluminescence Spectra ◽  
Discrete Energy ◽  
Discrete Energy Level ◽  
Size Uniformity ◽  
Gaas Quantum Dot

We investigate the effect of carrier dynamics on the temperature dependence of photoluminescence spectra from InAs/GaAs quantum dot heterostructures with different dot size uniformity. Intersublevel relaxation lifetimes and carrier transferring mechanisms are simulated using a model based on carriers relaxing and thermal emission of each discrete energy level in the quantum dot system. Calculated relaxation lifetimes are decreasing with temperature and have larger values for sample with lower dot size uniformity. In the quantitative discussion of carrier dynamics, the influence of thermal redistribution on carriers relaxing process of quantum dot system is demonstrated by our model.

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