scholarly journals Piezoelectric Field Effect on Optical Properties of GaN/GaInN/AlGaN Quantum Wells

1999 ◽  
Vol 4 (S1) ◽  
pp. 628-633 ◽  
Author(s):  
Jin Seo Im ◽  
H. Kollmer ◽  
O. Gfrörer ◽  
J. Off ◽  
F. Scholz ◽  
...  
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Field Effect ◽  
Blue Shift ◽  
Asymmetric Structure ◽  
Band Bending ◽  
Time Resolved ◽  
Model Calculations ◽  
Piezoelectric Field ◽  
Strained Quantum Well

We designed and studied two sample groups: first, GaInN/AlGaN/GaN quantum wells with asymmetric barrier structure and secondly, GaInN/GaN quantum wells with asymmetrically doped barriers. Time-resolved measurements on the asymmetric structure reveal an enhanced oscillator strength when the AlGaN barrier is on top of the GaInN quantum well, indicating a better carrier confinement in such a structure. The photoluminescence emission energy of the GaInN/GaN quantum well with doped GaN barriers shifts towards higher energy than that of undoped samples due to screening, but only when the GaN barrier layer below the quantum well is doped. In contrast, the sample where only a GaN cap layer above the quantum well is doped, shows no blue-shift. These results, showing asymmetries in GaInN/GaN quantum wells, provide confirming evidence of the piezoelectric field effect and allow us to determine the sign of the piezoelectric field, which points towards the substrate in a compressively strained quantum well. Furthermore, we performed model calculations of the global band bending and the screening effect, which consistently explain our experimental findings.

Piezoelectric Field Effect on Optical Properties of GaN/GaInN/AlGaN Quantum Wells

1998 ◽  
Vol 537 ◽  
Author(s):  
Jin Seo Im ◽  
H. Kollmer ◽  
O. Gfrörer ◽  
J. Off ◽  
F. Scholz ◽  
...  
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Field Effect ◽  
Blue Shift ◽  
Asymmetric Structure ◽  
Band Bending ◽  
Time Resolved ◽  
Model Calculations ◽  
Piezoelectric Field ◽  
Strained Quantum Well

AbstractWe designed and studied two sample groups: first, GaInN/AlGaN/GaN quantum wells with asymmetric barrier structure and secondly, GaInN/GaN quantum wells with asymmetrically doped barriers. Time-resolved measurements on the asymmetric structure reveal an enhanced oscillator strength when the AlGaN barrier is on top of the GaInN quantum well, indicating a better carrier confinement in such a structure. The photoluminescence emission energy of the GaInN/GaN quantum well with doped GaN barriers shifts towards higher energy than that of undoped samples due to screening, but only when the GaN barrier layer below the quantum well is doped. In contrast, the sample where only a GaN cap layer above the quantum well is doped, shows no blue-shift. These results, showing asymmetries in GaInN/GaN quantum wells, provide confirming evidence of the piezoelectric field effect and allow us to determine the sign of the piezoelectric field, which points towards the substrate in a compressively strained quantum well. Furthermore, we performed model calculations of the global band bending and the screening effect, which consistently explain our experimental findings.

Sign of the Piezoelectric Field in Asymmetric GaInN/AlGaN/GaN Single and Double Quantum Wells on SiC

1999 ◽  
Vol 595 ◽  
Author(s):  
Jin Seo Im ◽  
A. Hangleiter ◽  
J. Off ◽  
F. Scholz
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Oscillator Strength ◽  
Double Quantum ◽  
Barrier Structure ◽  
Time Resolved ◽  
Double Quantum Well ◽  
First Case ◽  
Algan Barrier ◽  
Piezoelectric Field

AbstractWe study both GaInN/GaN/AlGaN quantum wells with an asymmetric barrier structure grown on SiC substrate and GaN/AlGaN asymmetric double quantum well (ADQW) structures. In the first case, a time-resolved study reveals an enhanced oscillator strength when the AlGaN barrier is on top of the GaInN quantum well. In comparison to our previous study of the same structure grown on sapphire, we find that the sign of the field is the same in both cases: the field points towards the substrate. In the case of ADQW, we observed not only intrawell transitions of both a 4 nm and a 2 nm QW separated by a 2.5 nm AlGaN barrier but also an interwell transition between the two QWs in the photoluminescence. The lifetimes and emission energies of the transitions can be well explained by the existence of the piezoelectric field built in the QWs.

scholarly journals Electric Field Distribution in strained p-i-n GaN/InGaN multiple quantum well structures.

1999 ◽  
Vol 4 (1) ◽  
Author(s):  
A.N. Cartwright ◽  
Paul M. Sweeney ◽  
Thomas Prunty ◽  
David P. Bour ◽  
Michael Kneissl
Keyword(s):  
Quantum Well ◽  
Electric Field Distribution ◽  
Theoretical Calculations ◽  
Multiple Quantum Well ◽  
Multiple Quantum ◽  
Time Resolved ◽  
Quantum Well Structures ◽  
Piezoelectric Field ◽  
Piezoelectric Fields ◽  
Time Resolved Photoluminescence

The presence of piezoelectric fields within p-i-n GaN/InGaN multiple quantum well structures is discussed. Time integrated and time-resolved photoluminescence measurements and theoretical calculations of the effect of these fields is presented. Furthermore, a description of how these fields influence the carrier dynamics and a discussion of how the piezoelectric field effects the design of GaN/InGaN devices is presented.

AES and EELFS Studies of Initial Stages of Growth of GaAs/InAs/GaAs Heterostructures.

1988 ◽  
Vol 144 ◽  
Author(s):  
F. D. Schowengerdt ◽  
F. J. Grunthaner ◽  
John K. Liu
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Growth Parameters ◽  
High Energy ◽  
Model Calculations ◽  
Mbe Growth ◽  
Quantum Well Structures ◽  
Stages Of Growth ◽  
Double Heterostructures ◽  
Composition And Structure

ABSTRACTWe report on a systematic study of the composition and structure of GaAs/InAs/GaAs quantum wells using Auger Electron Spectroscopy (AES), Extended Energy Loss Fine Structure (EELFS), and Reflection High Energy Electron Diffraction (RHEED) techniques. Double heterostructures with InAs thickness ranging from 2 to 10 monolayers, capped by 2 to 10 monolayers of GaAs, were grown by MBE using a variety of techniques, including those employing sequential, interrupted, and delayed shutter timing sequences. AES peak ratios are compared with model calculations to monitor compositional development of the multilayers. The AES results are correlated with RHEED measurements to determine MBE growth parameters for optimal control of the stoichiometry and surface morphology. EELFS was used to monitor strain in the buried InAs layers. The AES results show departure from smooth laminar growth of layers of stoichiometric InAs on GaAs at temperatures below 420 C and above 470 C. AES results on the quantum well structures suggest floating InAs layers on top of the GaAs and/or facet formation in the GaAs layers. The EELFS results, when compared to bulk InAs, indicate the presence of strain in the buried InAs quantum well.

Doping-Dependent Nonlinear Electron Mobility in GaAs|In-=SUB=-x-=/SUB=-Ga-=SUB=-1-x-=/SUB=-As Coupled Quantum-Well Pseudo-Morphic MODFET Structure

2020 ◽  
Vol 54 (7) ◽  
pp. 676
Author(s):  
S.R. Panda ◽  
A. Sahu ◽  
S. Das ◽  
A.K. Panda ◽  
T. Sahu
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Electron Mobility ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Energy Levels ◽  
Interface Roughness ◽  
Double Quantum ◽  
Double Quantum Well ◽  
Alloy Disorder

We analyze the asymmetric delta-doping dependence of nonlinear electron mobility μ of GaAs|InxGa1-xAs double quantum-well pseudo-morphic modulation doped field-effect transistor structure. We solve the Schrodinger and Poisson's equations self-consistently to obtain the sub-band energy levels and wave functions. We consider scatterings due to the ionized impurities (IMP), alloy disorder (AL), and interface roughness (IR) to calculate μ for a system having double sub-band occupancy, in which the inter-sub-band effects play an important role. Considering the doping concentrations in the barriers towards the substrate and surface sides as Nd1 and Nd2, respectively, we show that variation of Nd1 leads to a dip in μ near Nd1=Nd2, at which the resonance of the sub-band states occurs. A similar dip in μ as a function of Nd1 is also obtained at Nd1=Nd2 by keeping (Nd1+Nd2) unchanged. By increasing the central barrier width and well width, the dip in μ becomes sharp. We note that even though the overall μ is governed by the IMP- and AL-scatterings, the dip in μ is mostly affected through substantial variation of the sub-band mobilities due to IR-scattering near the resonance. Our results of nonlinear electron mobility near the resonance of sub-band states can be utilized for the performance analysis of GaAs|InGaAs pseudo-morphic quantum-well field-effect transistors. Keywords: asymmetric double quantum wells, GaAs|InxGa1-xAs structures, nonlinear electron mobility, pseudo-morphic HEMT structures, resonance of sub-band states.

Lateral Diffusion Limitations of Ingaas/Gaas for Nanostructure Fabrication

1995 ◽  
Vol 380 ◽  
Author(s):  
Gregory F. Redinbo ◽  
Harold G. Craighead
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Lateral Diffusion ◽  
Blue Shift ◽  
Nanostructure Fabrication ◽  
Recombination Energy ◽  
Diffusion Limitations ◽  
High Temperature Anneal ◽  
Diffusion Effects ◽  
Hole Recombination

ABSTRACTWe have investigated the technique of implantation enhanced interdiffusion (IEI) for optical nanostructure fabrication in strained InxGal-xAs/GaAs quantum wells. Implantation masks with widths from 40 nm to 40 μm were fabricated on the surface of InxGal-xAs/GaAs (x+0.1, 0.2) 3.5 nm quantum well material which was implanted with 100 kV As+ with doses ranging from 5 × 1012 to 8.5× 1013 ions/cm2. After mask removal and a high temperature anneal, cathodoluminescence (CL) spectroscopy was used to investigate the optical properties of the resulting structures. We have measured electron-heavy hole recombination energy shifts due to quantum well interdiffusion of up to 60 meV for the highest doses used here with broad area implants. However, while quantum well emission under large (40 μm) masks is preserved, smaller masks show an emission blue shift not due to ions penetrating through the mask. A simple model of the width dependence of this shift yields an enhanced lateral diffusion length of approximately 1 μm which is many times larger than the lateral straggle of the implanted As+. We conclude that lateral diffusion effects may impose a limit on nanostructure fabrication in the InxGal-xAs/GaAs system with this technique.

1.95 μm Compressively Strained Ingaas/Ingaasp Quantum Well DFB Laser With Low Threshold

1997 ◽  
Vol 484 ◽  
Author(s):  
Jie Dong ◽  
Akinoi Ubukata ◽  
Koh Matsumoto
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Chemical Vapor ◽  
Double Quantum ◽  
Maximum Output ◽  
Quantum Well Structures ◽  
Double Quantum Well ◽  
Different Temperatures ◽  
Dfb Laser ◽  
Strained Quantum Well

AbstractIn this study, we demonstrate the growth of highly compressively strained InGaAs/JnGaAsP quantum well structures with large well thiclmess by low pressure metalorganic chemical vapor deposition for extending the emission wavelength of lasers. By comparing the photolumineswnce characteristics of quantum wells grown at different temperatures, it is clarified that a relatively high quality quantum well layer emittig at 2.0 μ, can be obtained at a growth temperature of 650°C. 1.95-μm-wavelength InGaAs/InGaAsP highly compressively strained quantum well DFB laser for laser spectroscopy monitors was also fabricated. Double quantum-well DFB laser operating at 1.95 μm exhibits threshold currents as low as 6 mA and 6.2 mW maximum output powers. 2.04-μm-wavelength DFB laser is also described.

ANOMALOUS SPECTRAL SHIFTS OF INDIRECT EXCITONS IN COUPLED GaAs QUANTUM WELLS

2001 ◽  
Vol 15 (28n30) ◽  
pp. 3606-3610 ◽  
Author(s):  
D. W. SNOKE ◽  
V. NEGOITA ◽  
D. HACKWORTH ◽  
K. EBERL
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Low Frequency ◽  
Blue Shift ◽  
Substrate Material ◽  
Excitation Density ◽  
Spectral Position ◽  
Indirect Excitons ◽  
Spectral Shifts ◽  
Resonant Laser

We have studied the energy shifts of indirect excitons consisting of an electron in one quantum well and a hole in an adjacent quantum well. Several surprising effects occur: (1) a very strong blue shift with increasing intensity of resonant laser excitation, (2) a very strong red shift with weak magnetic field, and (3) very low-frequency (sub-Hz) fluctuations of the spectral position at high excitation density. We discuss the effect of screening by carriers excited in the substrate material.

scholarly journals Photoluminescence measurements on GaN/AlGaN modulation doped quantum wells

1999 ◽  
Vol 4 (1) ◽  
Author(s):  
J. Dalfors ◽  
J. P. Bergman ◽  
P.O. Holtz ◽  
B. Monemar ◽  
H. Amano ◽  
...  
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Electron Gas ◽  
Energy Transition ◽  
Photoluminescence Spectra ◽  
Photoluminescence Decay ◽  
Fermi Edge ◽  
Decay Times ◽  
Piezoelectric Field ◽  
Good Agreement

Photoluminescence spectra were measured for 100 Å wurtzite GaN AlGaN modulation doped quantum wells. Three well-resolved peaks originate from the quantum well. The theoretically calculated confinement energies have been compared to the experimental energy positions and found to be in good agreement with the data, assuming that the piezoelectric field is largely screened by the electron gas. The highest energy transition may originate from the Fermi edge, consistent with the temperature dependence of the photoluminescence. Decay times for the different transitions indicate that the photoexcited holes are localized.

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