Contactless Electroreflectance Study of InxGa1-xAs/InP Multiple Quantum Well Structures Including the Observation of Surface/Interface Electric Fields

1996 ◽  
Vol 448 ◽  
Author(s):  
L.V. Malikova ◽  
J.Z. Wan ◽  
Fred H. Pollak ◽  
J.G. Simmons ◽  
D.A. Thompson
Keyword(s):  
Quantum Wells ◽  
Electric Fields ◽  
Multiple Quantum Well ◽  
Structure Identification ◽  
Multiple Quantum ◽  
Transform Method ◽  
Quantum Well Structures ◽  
Conduction Band Offset ◽  
Before And After ◽  
Sulfur Passivation

AbstractContactless electroreflectance measurements at 300 K were performed on two InxGal-xAs/InP ]x = 0.53 (lattice-matched) and 0.75] samples containing three quantum wells (QWs) grown by gas-source molecular beam epitaxy. The spectra consisted of two excitonic transitions (le-l hh and le-l lh), corresponding to the fundamental conduction to heavy (h)- and light(l)- hole transitions, respectively, in the QW portion and a complicated Franz-Keldysh oscillation (FKO) pattern originating in the InP regions. Comparison between the experimental energies of le-l hh/le-llh and a theoretical envelope function calculation (including the effect of strain) made it possible to evaluate the conduction band offset parameters Qc =0.34+0.03 and 0.57+0.03 for x = 0.53 and 0.75, respectively. The InP related FKO beat patterns were analyzed by a Fourier transform method. It was found that the FKO spectra were due to the simultaneous contribution of at least three different fields (106 kV/cm, 36 kV/cm, and 23 kV/cm), which originate in the various interfaces, i.e., substrate/buffer, cap layer/surface, and buffer/QW structure. Identification of the different fields has been accomplished by comparison of the Fourier-transformed spectra before and after sulfur passivation of the structure surface.

scholarly journals Luminescent Characteristics of InGaAsP/InP Multiple Quantum Well Structures by Impurity-Free Vacancy Disordering

2001 ◽  
Vol 692 ◽  
Author(s):  
J. Zhao ◽  
X. D. Zhang ◽  
Z. C. Feng ◽  
J. C. Deng ◽  
P. Jin ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Band Gap ◽  
Annealing Temperature ◽  
Multiple Quantum Well ◽  
Blue Shift ◽  
Multiple Quantum ◽  
Quantum Well Structures ◽  
Cladding Layer ◽  
Cap Layer ◽  
Free Vacancy

AbstractInGaAsP/InP multiple quantum wells have been prepared by Impurity-Free Vacancy Disordering (IFVD). The luminescent characteristics was investigated using photoluminescence (PL) and photoreflectance (PR), from which the band gap blue shift was observed. Si3N4, SiO2 and SOG were used for the dielectric layer to create the vacancies. All samples were annealed by rapid thermal anne aling (RTA). The results indicate that the band gap blue shift varies with the dielectric layers and annealing temperature. The SiO2 capping was successfully used with an InGaAs cladding layer to cause larger band tuning effect in the InGaAs/InP MQWs than the Si3N4 capping with an InGaAs cladding layer. On the other hand, samples with the Si3N4-InP cap layer combination also show larger energy shifts than that with SiO2-InP cap layer combination.

scholarly journals Piezoelectric Level Splitting in GaInN/GaN Quantum Wells

1999 ◽  
Vol 4 (S1) ◽  
pp. 357-362
Author(s):  
C. Wetzel ◽  
T. Takeuchi ◽  
H. Amano ◽  
I. Akasaki
Keyword(s):  
Quantum Wells ◽  
Electric Fields ◽  
High Performance ◽  
Stark Effect ◽  
Electronic Band Structure ◽  
Multiple Quantum Well ◽  
Multiple Quantum ◽  
Large Set ◽  
Electronic Band ◽  
Level Splitting

Identification of the electronic band structure in AlInGaN heterostructures is the key issue in high performance light emitter and switching devices. In device-typical GaInN/GaN multiple quantum well samples in a large set of variable composition a clear correspondence of transitions in photo- and electroreflection, as well as photoluminescence is found. The effective band offset across the GaN/GaInN/GaN piezoelectric heterointerface is identified and electric fields from 0.23 - 0.90 MV/cm are directly derived. In the bias voltage dependence a level splitting within the well is observed accompanied by the quantum confined Stark effect. We furthermore find direct correspondence of luminescence bands with reflectance features. This indicates the dominating role of piezoelectric fields in the bandstructure of such typical strained layers.

scholarly journals Photo- and cathodoluminescence investigations of piezoelectric GaN/AlGaN quantum wells

2000 ◽  
Vol 639 ◽  
Author(s):  
E.M. Goldys ◽  
M. Godlewski ◽  
M.R. Phillips ◽  
A.A. Toropov
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Electric Fields ◽  
Free Exciton ◽  
Multiple Quantum Well ◽  
Depth Profiling ◽  
Multiple Quantum ◽  
Recombination Mechanism ◽  
Decay Times ◽  
Piezoelectric Fields

ABSTRACTWe have examined multiple quantum well AlGaN/GaN structures with several quantum wells of varying widths. The structures had strain-free quantum wells and strained barriers. Strong piezoelectric fields in these structures led to a large red shift of the PL emission energies and long decay times were also observed. While the peak energies could be modelled using the effective mass approximation, the calculated free exciton radiative lifetimes were much shorter than those observed in experiments, indicating an alternative recombination mechanism, tentatively attributed to localised excitons. Cathodoluminescence depth profiling revealed an unusually small penetration range of electrons suggesting that electron-hole pairs preferentially remain within the multiple quantum well region due to the existing electric fields. Spatial fluctuations of the cathodoluminescence intensity were also observed.

scholarly journals Piezoelectric Level Splitting in GaInN/GaN Quantum Wells

1998 ◽  
Vol 537 ◽  
Author(s):  
C. Wetzel ◽  
T. Takeuchi ◽  
H. Amano ◽  
I. Akasaki
Keyword(s):  
Quantum Wells ◽  
Electric Fields ◽  
High Performance ◽  
Stark Effect ◽  
Electronic Band Structure ◽  
Multiple Quantum Well ◽  
Multiple Quantum ◽  
Large Set ◽  
Electronic Band ◽  
Level Splitting

AbstractIdentification of the electronic band structure in AlInGaN heterostructures is the key issue in high performance light emitter and switching devices. In device-typical GaInN/GaN multiple quantum well samples in a large set of variable composition a clear correspondence of transitions in photo- and electroreflection, as well as photoluminescence is found. The effective band offset across the GaN/GaInN/GaN piezoelectric heterointerface is identified and electric fields from 0.23 - 0.90 MV/cm are directly derived. In the bias voltage dependence a level splitting within the well is observed accompanied by the quantum confined Stark effect. We furthermore find direct correspondence of luminescence bands with reflectance features. This indicates the dominating role of piezoelectric fields in the bandstructure of such typical strained layers.

scholarly journals Luminescent Characteristics of InGaAsP/InP Multiple Quantum Well Structures by Impurity-Free Vacancy Disordering

2001 ◽  
Vol 693 ◽  
Author(s):  
J. Zhao ◽  
X. D. Zhang ◽  
Z. C. Feng ◽  
J. C. Deng ◽  
P. Jin ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Band Gap ◽  
Annealing Temperature ◽  
Multiple Quantum Well ◽  
Blue Shift ◽  
Multiple Quantum ◽  
Quantum Well Structures ◽  
Cladding Layer ◽  
Cap Layer ◽  
Free Vacancy

AbstractInGaAsP/InP multiple quantum wells have been prepared by Impurity-Free Vacancy Disordering (IFVD). The luminescent characteristics was investigated using photoluminescence (PL) and photoreflectance (PR), from which the band gap blue shift was observed. Si3N4, SiO2 and SOG were used for the dielectric layer to create the vacancies. All samples were annealed by rapid thermal anne aling (RTA). The results indicate that the band gap blue shift varies with the dielectric layers and annealing temperature. The SiO2 capping was successfully used with an InGaAs cladding layer to cause larger band tuning effect in the InGaAs/InP MQWs than the Si3N4 capping with an InGaAs cladding layer. On the other hand, samples with the Si3N4-InP cap layer combination also show larger energy shifts than that with SiO2-InP cap layer combination.

Emission Mechanisms in UV Emitting GaN/AlN Multiple Quantum Well Structures

2003 ◽  
Vol 798 ◽  
Author(s):  
Madalina Furis ◽  
Alexander N. Cartwright ◽  
Hong Wu ◽  
William J. Schaff
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Temperature Dependence ◽  
Multiple Quantum Well ◽  
Activation Energies ◽  
Inhomogeneous Broadening ◽  
Binding Energies ◽  
Multiple Quantum ◽  
Quantum Well Structures ◽  
Donor And Acceptor

ABSTRACTThe need for efficient UV emitting semiconductor sources has prompted the study of a number of heterostructures of III-N materials. In this work, the temperature dependence of the photoluminescence (PL) properties of UV-emitting GaN/AlN multiple quantum well (MQW) heterostructures were investigated in detail. In all samples studied, the structure consisted of 20 GaN quantum wells, with well widths varying between 7 and 15 Å, clad by 6nm AlN barriers, grown on top of a thick AlN buffer that was deposited on sapphire by molecular beam epitaxy. The observed energy corresponding to the peak of the emission spectrum is in agreement with a model that includes the strong confinement present in these structures and the existence of the large built-in piezoelectric field and spontaneous polarization present inside the wells. The observed emission varies from 3.5 eV (15 Å well) to 4.4 eV (7 Å well). Two activation energies associated with the photoluminescence quenching are extracted from the temperature dependence of the time-integrated PL intensity. These activation energies are consistent with donor and acceptor binding energies and the PL is dominated by recombination involving carriers localized on donor and/or acceptor states.Moreover, the temperature dependence of the full width at half-maximum (FWHM) of the PL feature indicates that inhomogeneous broadening dominates the spectrum at all temperatures. For the 15 and 13 Å wells, we estimate that the electron-phonon interaction is responsible for less than 30% of the broadening at room temperature. This broadening is negligible in the 9 Å wells over the entire temperature range studied. Well width fluctuations are primarily responsible for the inhomogeneous broadening, estimated to be of the order of 250meV for one monolayer fluctuation in well width.

GaAs–AlGaAs multiple-quantum-well lasers for monolithic integration with optical modulators

1991 ◽  
Vol 69 (3-4) ◽  
pp. 491-496 ◽  
Author(s):  
F. Chatenoud ◽  
K. M. Dzurko ◽  
M. Dion ◽  
D. Moss ◽  
R. Barber ◽  
...  
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Cavity Length ◽  
Multiple Quantum Well ◽  
Monolithic Integration ◽  
Quantum Well Lasers ◽  
Multiple Quantum ◽  
Optical Modulators ◽  
Single Quantum Well ◽  
Quantum Well Structures

Calculations of multiple-quantum-well laser threshold current show that a common minimum current value exists for each number of wells, at an appropriate cavity length. This optimum cavity length decreases rapidly with increasing number of wells, for instance from about 300 to 110 μm for one to three wells. Granded-index separate-confinement heterostructure (GRINSCH) lasers with 1–10 quantum wells, grown by molecular beam epitaxy, show consistently low threshold currents that agree well with theoretical predictions. Lasing is achieved at 160 A cm−2 and 4.6 mA for broad-area and ridge waveguide single-quantum-well devices, respectively. The field-dependent electroabsorption of these devices when operating as wave-guide modulators indicates good modulation properties for one and three quantum-well structures, with on:off ratios above 55 at lasing wavelength. The behavior becomes more complex with increasing number of wells. This systematic study of discrete multiple-quantum-well lasers and modulators demonstrates that GRINSCH structures with 1–3 wells are the most suitable for monolithic integration. Design rules for the laser cavity are also presented for numbers of wells ranging from 1 to 10.

Electron–electron inter-subband scattering in GaAs quantum wells

1996 ◽  
Vol 74 (S1) ◽  
pp. 252-255
Author(s):  
Zhi Zhong Xu ◽  
D. Morris
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Electron Scattering ◽  
Multiple Quantum Well ◽  
Golden Rule ◽  
Multiple Quantum ◽  
Hot Electron ◽  
Quantum Well Structures ◽  
Scattering Rate ◽  
Relaxation Channel

The role of electron–electron scattering in the dynamics of inter-subband relaxation in GaAs quantum wells is investigated theoretically. The scattering rate is calculated using the Fermi golden rule, as a function of the carrier densities. The dependence of the inter-subband relaxation time on the quantum-well width is also investigated. Calculations are performed for multiple quantum-well structures with well widths varying from 80 to 240 Å (1 Å = 10−10 m). The hot electron distribution and the subband occupation function are taken into account in these calculations. Results show that the electron–electron scattering rate increases linearly as a function of the carrier densities. A band-filling effect limits the efficiency of this mechanism under high carrier densities (> 1012 cm−2). For thick well (180 Å) structures, this relaxation channel is as efficient as the phonon relaxation channel.

Laser-Modified Chemical Beam Epitaxy of InGaAs/GaAs Multiple Quantum Wells Using Tris-Dimethylaminoarsenic

1994 ◽  
Vol 354 ◽  
Author(s):  
H.K. Dong ◽  
N.Y. Li ◽  
C.W. Tu
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Laser Irradiation ◽  
Multiple Quantum Well ◽  
Multiple Quantum ◽  
Chemical Beam Epitaxy ◽  
Quantum Well Structures ◽  
X Ray ◽  
Strained Quantum Well ◽  
First Time

AbstractWe report for the first time laser-modified chemical beam epitaxy (CBE) of InGaAs/GaAs multiple quantum well (MQW) structures using trimethylindium (TMIn), triethylgallium (TEGa), and tris-dimethylaminoarsenic (TDMAAs), a safer alternative to arsine. X-ray rocking curve (XRC) and low-temperature photoluminescence (PL) measurements were used to characterize the pseudomorphic strained quantum well structures. As determined by the X-ray simulation, laser irradiation during the InGaAs well growth was found to enhance the InGaAs growth rate and reduce the indium concentration in the substrate temperature range studied, 440-S00°C, where good interfaces can be achieved. We attribute these changes to laser-enhanced decomposition of TEGa and laser-enhanced desorption of TDMAAs. With laser irradiation, lateral variation of PL exciton peaks was observed, and the PL peaks became narrower.

MOCVD Growth and Characterization of GaInNAs/GaAs/InGaAs/GaAs Quantum Well Structures

2002 ◽  
Vol 744 ◽  
Author(s):  
Abdel-Rahman A. El-Emawy ◽  
Hongjun Cao ◽  
Noppadon Nuntawong ◽  
Chiyu Liu ◽  
Marek Osiński
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Growth Parameters ◽  
Multiple Quantum Well ◽  
Double Quantum ◽  
Multiple Quantum ◽  
Quantum Well Structures ◽  
Mocvd Growth ◽  
Double Quantum Well ◽  
Wavelength Emission

ABSTRACTEffects of MOCVD growth parameters on structural and optical properties of double-quantum-well (DQW) structures containing uncoupled GaInNAs/GaAs and InGaAs/GaAs quantum wells have been investigated. By varying growth temperature, growth rate, V/III ratio, and DMHy flow rates, we have achieved a longer-wavelength emission from a GaInNAs well than from an InGaAs well grown in the same structure. GaInNAs/GaAs multiple-quantum-well structures grown under optimum conditions emitted at 1.25 μm.

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