TEMPERATURE DEPENDENCE OF PHOTOLUMINESCENCE OF FLAT AND UNDULATED SiGe/Si MULTIPLE QUANTUM WELLS

2002 ◽  
Vol 16 (28n29) ◽  
pp. 4211-4214 ◽  
Author(s):  
B. W. CHENG ◽  
J. G. ZHANG ◽  
Y. H. ZUO ◽  
R. W. MAO ◽  
C. J. HUANG ◽  
...  
Keyword(s):  
Elevated Temperature ◽  
Quantum Wells ◽  
Blue Shift ◽  
Band Alignment ◽  
Multiple Quantum Wells ◽  
Luminescence Spectra ◽  
Multiple Quantum ◽  
Type Ii ◽  
Thermally Activated ◽  
Strained Sige

Photoluminescence (PL) of strained SiGe/Si multiple quantum wells (MQW) with flat and undulated SiGe well layers was studied at different temperature. With elevated temperature from 10K, the no-phonon (NP) peak of the SiGe layers in the flat samples has firstly a blue shift due to the dominant transition converting from bound excitons (BE) to free excitons (FE), and then has a red shift when the temperature is higher than 30K because of the narrowing of the band gap. In the undulated sample, however, monotonous blue shift was observed as the temperature was elevated from 10 K to 287 K. The thermally activated electrons, confined in Si due to type-II band alignment, leak into the SiGe crest regions, and the leakage is enhanced with the elevated temperature. It results in a blue shift of the SiGe luminescence spectra.

Optical characterization of type-II ZnO/ZnS multiple quantum wells grown by atomic layer deposition

2020 ◽  
Vol 694 ◽  
pp. 137740 ◽  
Author(s):  
Mostafa Afifi Hassan ◽  
Aadil Waseem ◽  
Muhammad Ali Johar ◽  
Sou Young Yu ◽  
June Key Lee ◽  
...  
Keyword(s):  
Atomic Layer Deposition ◽  
Quantum Wells ◽  
Atomic Layer ◽  
Optical Characterization ◽  
Multiple Quantum Wells ◽  
Multiple Quantum ◽  
Type Ii ◽  
Layer Deposition

Blue Shifting of Hydrogenated Silicon Carbide Multiple Quantum Wells

2011 ◽  
Vol 480-481 ◽  
pp. 629-633
Author(s):  
Wen Teng Chang ◽  
Yu Ting Chen ◽  
Chung Chin Kuo
Keyword(s):  
Silicon Carbide ◽  
Quantum Wells ◽  
Quantum Confinement Effect ◽  
Chemical Vapor ◽  
Blue Shift ◽  
Multiple Quantum Wells ◽  
Multiple Quantum ◽  
Plasma Chemical ◽  
Hydrogenated Silicon ◽  
Plasma Chemical Vapor Deposition

Five-period hydrogenated silicon carbide (SiC) multiple quantum wells with silicon dioxide (SiO2) or silicon nitride (SiN) dielectric that were synthesized by high density plasma chemical vapor deposition were studied using photoluminescence (PL) spectroscopy to understand its blue shift. Rapid thermal annealing induced significant blue shifting in the PL spectra after fluorine ion implantation due to crystallization. The thinning of the SiC causes blue shift due to the quantum confinement effect. The higher PL intensity of the amorphous SiC:H in SiO2 than in SiC/SiN may be attributed to the high number of non-radiative sites on its surface. Annealing with nitrogen may cause impurities in SiC/SiO2, thereby broadening the PL peak.

The Emission Properties of Light Emitting Diodes using InGaN/AlGaN/GaN Multiple Quantum Wells

1998 ◽  
Vol 3 ◽  
Author(s):  
A. E. Yunovich ◽  
V. E. Kudryashov ◽  
A. N. Turkin ◽  
A. Kovalev ◽  
F. Manyakhin
Keyword(s):  
Quantum Wells ◽  
Quantum Efficiency ◽  
Light Emitting Diodes ◽  
Multiple Quantum Wells ◽  
Luminescence Spectra ◽  
Multiple Quantum ◽  
Tunnel Current ◽  
High Quantum Efficiency ◽  
Light Emitting ◽  
Low Probability

Luminescence spectra of Light Emitting Diodes (LEDs) with Multiple Quantum Wells (MQWs) were studied at currents J = 0.15 μA - 150 mA. A high quantum efficiency at low J is caused by a low probability of the tunnel current J (which is maximum at Jm ≈ 0.5-1.0 mA). J(V) curves were measured in the range J= 10−12-10−1 A; at J > 10−3A they may be approximated by a sum of four parts: V= φk+ mkT·[ln(J/J0)+(J/J1)0.5] + J·Rs. The part V ~ (J/J1)0.5is the evidence of a double-injection into i-layers near MQWs. Their presence is confirmed by capacitance measurements. An overflow of carriers through the MQW causes a lower quantum efficiency at high J. A model of a 2D-density of states with exponential tails fits the spectra. The value of T in the active layer was estimated. A new band was detected at high J; it can be caused by non-uniformity of In content in MQWs.

Terahertz intersubband absorption and conduction band alignment inn-type Si/SiGe multiple quantum wells

2009 ◽  
Vol 79 (8) ◽  
Author(s):  
G. Ciasca ◽  
M. De Seta ◽  
G. Capellini ◽  
F. Evangelisti ◽  
M. Ortolani ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Conduction Band ◽  
Band Alignment ◽  
Multiple Quantum Wells ◽  
Multiple Quantum ◽  
Intersubband Absorption

Temperature Dependence of Cathodoluminescence From InxGa1-xAs/GaAs Multiple Quantum Wells

1995 ◽  
Vol 379 ◽  
Author(s):  
K. Rammohan ◽  
D.H. Rich ◽  
A. Larsson
Keyword(s):  
Activation Energy ◽  
Quantum Wells ◽  
Temperature Dependence ◽  
Spatial Variations ◽  
Multiple Quantum Wells ◽  
Multiple Quantum ◽  
Misfit Dislocations ◽  
Nonradiative Recombination ◽  
Intensity Dependence ◽  
Thermally Activated

ABSTRACTThe temperature dependence of the cathodoluminescence (CL) originating from In0.21Ga0.79As/GaAs multiple quantum wells has been studied between 86 and 250 K. The CL intensity exhibits an Arrenhius-type dependence on temperature (T), characterized by two different activation energies. The spatial variations in activation energy caused by the presence of interfacial misfit dislocations is examined. The CL intensity dependence on temperature for T ≲ 150 K is controlled by thermally activated nonradiative recombination. For T ≳ 150 K the decrease in CL intensity is largely influenced by thermal re-emission of carriers out of the quantum wells.

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