Cathodoluminescence depth-profiling studies of GaN/AlGaN quantum-well structures

2000 ◽  
Vol 15 (2) ◽  
pp. 495-501 ◽  
Author(s):  
M. Godlewski ◽  
E. M. Goldys ◽  
M. R. Phillips ◽  
R. Langer ◽  
A. Barski
Keyword(s):  
Electric Field ◽  
Quantum Well ◽  
Quantum Wells ◽  
Piezoelectric Effect ◽  
Depth Profiling ◽  
Yellow Emission ◽  
Internal Electric Field ◽  
Edge Emission ◽  
Quantum Well Structures ◽  
Accumulation Of Defects

In this paper we evaluate the in-depth homogeneity of GaN epilayers and the influence of electric field present in strained GaN/AlGaN heterostructures and quantum wells on the yellow and “edge” emission in GaN and AlGaN. Our depth-profiling cathodoluminescence measurements show an increased accumulation of defects at the interface. Inhomogeneities in the doping level are reflected by the enhancement of the yellow emission in the interface region. The piezoelectric effect is found to strongly reduce the emission from the strained AlGaN quantum-well barriers. We also show that Ga droplets, commonly found on surfaces of samples grown in Ga-rich conditions, screen the internal electric field in a structure and thus result in a local enhancement of the edge emission intensity.

Quantum Confinement Stark Effect of Different Gainnas Quantum Well Structures

2013 ◽  
Vol 773 ◽  
pp. 622-627
Author(s):  
Ying Ning Qiu ◽  
Wei Sheng Lu ◽  
Stephane Calvez
Keyword(s):  
Electric Field ◽  
Quantum Well ◽  
Quantum Wells ◽  
External Electric Field ◽  
Quantum Confinement ◽  
Stark Effect ◽  
Band Gap Energy ◽  
Electron Effective Mass ◽  
Coupled Quantum Wells ◽  
Quantum Well Structures

The quantum confinement Stark effect of three types of GaInNAs quantum wells, namely single square quantum well, stepped quantum wells and coupled quantum wells, is investigated using the band anti-crossing model. The comparison between experimental observation and modeling result validate the modeling process. The effects of the external electric field and localized N states on the quantized energy shifts of these three structures are compared and analyzed. The external electric field applied to the QW not only changes the potential profile but also modulates the localized N states, which causes band gap energy shifts and increase of electron effective mass.

Nonlinear optical properties in the laser-dressed two-level AlxGa1−xN/GaN single quantum well

2018 ◽  
Vol 32 (04) ◽  
pp. 1850032 ◽  
Author(s):  
Monalisa Panda ◽  
Tapaswini Das ◽  
B. K. Panda
Keyword(s):  
Electric Field ◽  
Quantum Well ◽  
Quantum Wells ◽  
Effective Mass ◽  
Nonlinear Optical ◽  
Energy Levels ◽  
Internal Electric Field ◽  
Single Quantum ◽  
Single Quantum Well ◽  
Increase With Increase

The electronic states in the laser-dressed hexagonal and cubic Al[Formula: see text]Ga[Formula: see text]N/GaN single quantum wells are calculated using the effective mass equation. The hexagonal single quantum well contains an internal electric field due to spontaneous and piezoelectric polarizations. The effective mass equation is solved by the finite difference method. The energy levels in both cubic and hexagonal laser-dressed wells are found to increase with increase in laser dressing as the effective well widths in both the wells increase. The intersubband energy spacing between first excited state and ground state increases in the cubic quantum well, whereas it decreases in the hexagonal well due to the presence of internal electric field in it. Using the compact density matrix method with iterative procedure, first-, second- and third-order nonlinear optical susceptibilities in the laser-dressed quantum well are calculated taking only two levels. While the susceptibilities in the hexagonal well are found to get red shifted, the susceptibilities in the cubic well are blue shifted.

scholarly journals The impact of electron and hole trapping coefficient on nonlinear phenomena in photorefractive multiple quantum well structures

2016 ◽  
Vol 8 (4) ◽  
pp. 125
Author(s):  
Blazej Jablonski ◽  
Andrzej Ziolkowski ◽  
Agnieszka Branecka ◽  
Ewa Weinert-Raczka
Keyword(s):  
Electric Field ◽  
Quantum Well ◽  
Quantum Wells ◽  
Multiple Quantum Well ◽  
Nonlinear Phenomena ◽  
Multiple Quantum ◽  
Wave Mixing ◽  
Quantum Well Structures ◽  
Hole Trapping ◽  
Two Wave Mixing

Semiconductor photorefractive quantum wells belong to materials with strong optical nonlinearity. One of the parameters that may affect the course of nonlinear phenomena in these materials is the electron and hole trapping coefficient. We present the results of a numerical analysis aimed to find out, how electric field-dependent trapping coefficients affect the process of space-charge field formation in multiple quantum wells in the phenomenon of photorefractive two-wave mixing. Full Text: PDF ReferencesQ. Wang, R. M. Brubaker, D. D. Nolte and M. R. Melloch, "Photorefractive quantum wells: transverse Franz-Keldysh geometry," J. Opt. Soc. Am. B 9, 1626 (1992) CrossRef D.D. Nolte and M.R. Melloch, in: Photorefractive effects and Materials, Chap.6, ed. by D. D. Nolte (Kluwer Academic, Boston, 1995) CrossRef D.D. Nolte, "Semi-insulating semiconductor heterostructures: Optoelectronic properties and applications"", J. Appl. Phys. 85, 6259 (1999) CrossRef Q.Wang, R. M. Brubaker and D. D. Nolte, "Photorefractive phase shift induced by hot-electron transport: Multiple-quantum-well structures", J. Opt. Soc. Am. B 9 (1994) 1773. CrossRef V. Ya. Prinz, S. N. Rechkunov, "Influence of a Strong Electric Field on the Carrier Capture by nonradiative Deep-Level Centers in GaAs", Phys. Stat. Sol. (b) 118, 159 (1983) CrossRef S.M. Sze, Physics of Semiconductors Devices, second ed., Wiley, New York, 1981 (Chapter 10) DirectLink B. Jablonski, "Impact of donor compensation ratio on photorefractive two-wave mixing dynamics in multiple quantum wells structures", JNOPM 23, 1450029 (2014) CrossRef

Light Emission Properties of GaN-Based Double Heterostructures and Quantum Wells

1995 ◽  
Vol 395 ◽  
Author(s):  
D.A.S. Loeber ◽  
J.M. Redwing ◽  
N.G. Anderson ◽  
M.A. Tischler
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Stimulated Emission ◽  
Pump Light ◽  
Band Edge Emission ◽  
Emission Characteristics ◽  
Nitrogen Laser ◽  
Edge Emission ◽  
Edge Luminescence ◽  
Double Heterostructures

ABSTRACTEdge emission characteristics of optically pumped GaN-AlGaN double heterostructures and quantum wells are examined. The samples, which were grown by metalorganic vapor phase epitaxy, are photoexcited with light from a pulsed nitrogen laser. The pump light is focused to a narrow stripe on the sample surface, oriented perpendicular to a cleaved edge, and the edge luminescence is collected and analyzed. We first compare emission characteristics of highly excited GaN-AlGaN double heterostructures grown simultaneously on SiC and sapphire substrates. Polarization resolved spectral properties of edge luminescence from both structures is studied as a function of pump intensity and excitation stripe length. Characteristics indicative of stimulated emission are observed, particularly in the sample grown on SiC. We then present results demonstrating laser emission from a GaN-AlGaN separate-confinement quantum-well heterostructure. At high pump intensities, band edge emission from the quantum well exhibits five narrow (∼1 Å) modes which are evenly spaced by 10Å to within the resolution of the spectrometer. This represents the first demonstration of laser action in a GaN-based quantum-well structure.

Effects of reduced internal electric field in InGaN/pseudo-AlInGaN multi-quantum-well on forward leakage current and photocurrent properties

2019 ◽  
Vol 126 (4) ◽  
pp. 045703 ◽  
Author(s):  
Byung-Guon Park ◽  
Reddeppa Maddaka ◽  
Thi Kim Phung Nguyen ◽  
Koteswara Rao Peta ◽  
Young-Kyun Noh ◽  
...  
Keyword(s):  
Electric Field ◽  
Quantum Well ◽  
Leakage Current ◽  
Internal Electric Field ◽  
Multi Quantum Well

Electric field dependence of optical absorption near the band gap of quantum-well structures

1985 ◽  
Vol 32 (2) ◽  
pp. 1043-1060 ◽  
Author(s):  
D. A. B. Miller ◽  
D. S. Chemla ◽  
T. C. Damen ◽  
A. C. Gossard ◽  
W. Wiegmann ◽  
...  
Keyword(s):  
Optical Absorption ◽  
Electric Field ◽  
Quantum Well ◽  
Band Gap ◽  
Field Dependence ◽  
Quantum Well Structures ◽  
Electric Field Dependence

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.

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