Optical evaluation of pretreated InGaN quantum well structures

2003 ◽  
Vol 798 ◽  
Author(s):  
T. Böttcher ◽  
F. Bertram ◽  
P. Bergman ◽  
A. Ueta ◽  
J. Christen ◽  
...  
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Room Temperature ◽  
Growth Direction ◽  
Wetting Layer ◽  
Quantum Well Structures ◽  
Room Temperature Photoluminescence ◽  
Decay Times ◽  
Wavelength Distribution ◽  
Ingan Quantum Wells

ABSTRACTIn order to optimize the quantum efficiency of InGaN quantum wells, different MOVPE growth sequences are compared using photo- and electroluminescence. In one study, the surface was pretreated with trimethylindium (TMIn) prior to the well deposition. In another study, growth interruptions were performed after the quantum well deposition to desorb segregated indium. In both cases, the room-temperature photoluminescence (PL) intensity is strongly enhanced. For the samples grown with TMIn preflow the wavelength distribution in low-temperature cathodoluminescence (CL) wavelength mappings is narrowed, which can be attributed to more homogeneous quantum wells. Furthermore, the decay times of the radiative recombination increase both at RT and 2K. A reason for this could be an improved indium profile along the growth direction or a more homogeneous In wetting layer due to the pre-wetted surface.

scholarly journals Room temperature PL efficiency of InGaN/GaN quantum well structures with prelayers as a function of number of quantum wells

2016 ◽  
Vol 13 (5-6) ◽  
pp. 248-251 ◽  
Author(s):  
George M. Christian ◽  
Simon Hammersley ◽  
Matthew J. Davies ◽  
Philip Dawson ◽  
Menno J. Kappers ◽  
...  
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Room Temperature ◽  
Quantum Well Structures

SHALLOW DONORS IN A COUPLED TRIPLE GRADED QUANTUM WELL UNDER THE ELECTRIC AND MAGNETIC FIELDS

2006 ◽  
Vol 13 (04) ◽  
pp. 397-401 ◽  
Author(s):  
E. KASAPOGLU ◽  
H. SARI ◽  
I. SÖKMEN
Keyword(s):  
Binding Energy ◽  
Quantum Well ◽  
Quantum Wells ◽  
Electric Fields ◽  
Growth Direction ◽  
Physical Parameters ◽  
Donor Impurity ◽  
Quantum Well Structures ◽  
Hydrogenic Donor Impurity ◽  
Electric And Magnetic Fields

The binding energy of the donor in three different shaped triple graded GaAs -( Ga , Al ) As quantum wells which is obtained by changing the depth of the central-well potential (Vo) is calculated by using a variational approach. The results have been obtained in the presence of uniform magnetic and electric fields applied along the growth direction as a function of the impurity position. In addition, we also give the binding energy of the hydrogenic donor impurity for triple square quantum wells having the same physical parameters with triple graded quantum well structures in order to see the effect of different geometric confinements on the donor impurity binding energy.

Interband transitions dependent on indium concentration in Ga1−xInxAs/GaAs asymmetric triple quantum wells

2018 ◽  
Vol 32 (05) ◽  
pp. 1850052 ◽  
Author(s):  
B. O. Alaydin ◽  
E. Ozturk ◽  
S. Elagoz
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Electronic Properties ◽  
Radiative Decay ◽  
Interband Transition ◽  
Energy Levels ◽  
Oscillator Strengths ◽  
Quantum Well Structures ◽  
Transition Energies ◽  
Decay Times

In this paper, the optical and electronic properties of asymmetric triple quantum well (ATQW) structures are studied depending on the indium concentrations while quantum well (QW) thicknesses and barrier widths are kept constant. Calculation of electronic properties are done within the framework of the effective mass approximation. The indium concentrations in left quantum well (LQW) and right quantum well (RQW) are varied in order to see the change of energy levels. Then, interband transition energies, wavelengths, oscillator strengths and radiative decay times are determined depending on barrier height. The scope of this study, for the first time in the literature, covers converged interband transition energies for the asymmetric quantum well structures.

scholarly journals Effects of a Si-doped InGaN Underlayer on the Optical Properties of InGaN/GaN Quantum Well Structures with Different Numbers of Quantum Wells

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1736 ◽  
Author(s):  
George Christian ◽  
Menno Kappers ◽  
Fabien Massabuau ◽  
Colin Humphreys ◽  
Rachel Oliver ◽  
...  
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Quantum Efficiency ◽  
Radiative Recombination ◽  
Room Temperature ◽  
Internal Quantum Efficiency ◽  
Thermionic Emission ◽  
Radiative Recombination Rate ◽  
Quantum Well Structures ◽  
Si Doped

In this paper we report on the optical properties of a series of InGaN polar quantum well structures where the number of wells was 1, 3, 5, 7, 10 and 15 and which were grown with the inclusion of an InGaN Si-doped underlayer. When the number of quantum wells is low then the room temperature internal quantum efficiency can be dominated by thermionic emission from the wells. This can occur because the radiative recombination rate in InGaN polar quantum wells can be low due to the built-in electric field across the quantum well which allows the thermionic emission process to compete effectively at room temperature limiting the internal quantum efficiency. In the structures that we discuss here, the radiative recombination rate is increased due to the effects of the Si-doped underlayer which reduces the electric field across the quantum wells. This results in the effect of thermionic emission being largely eliminated to such an extent that the internal quantum efficiency at room temperature is independent of the number of quantum wells.

Electroabsorption by Stark effect on room‐temperature excitons in GaAs/GaAlAs multiple quantum well structures

1983 ◽  
Vol 42 (10) ◽  
pp. 864-866 ◽  
Author(s):  
D. S. Chemla ◽  
T. C. Damen ◽  
D. A. B. Miller ◽  
A. C. Gossard ◽  
W. Wiegmann
Keyword(s):  
Quantum Well ◽  
Room Temperature ◽  
Stark Effect ◽  
Multiple Quantum Well ◽  
Multiple Quantum ◽  
Quantum Well Structures

45° REFLECTOMETRY OF SEMICONDUCTOR QUANTUM WELLS

2001 ◽  
Vol 15 (17n19) ◽  
pp. 683-687
Author(s):  
A. SILVA-CASTILLO ◽  
F. PEREZ-RODRIGUEZ
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Growth Direction ◽  
Angle Of Incidence ◽  
Near Surface ◽  
New Information ◽  
Difference Formula ◽  
Exciton Polaritons ◽  
The Difference ◽  
First Time

We have applied the 45° reflectometry for the first time to study exciton-polaritons in quantum wells. The 45° reflectometry is a new polarization-modulation technique, which is based on the measurement of the difference [Formula: see text] between the p-polarization reflectivity (Rp) and the squared s-polarization reflectivity [Formula: see text] at an angle of incidence of 45°. We show that [Formula: see text] spectra may provide qualitatively new information on the exciton-polariton modes in a quantum well. These optical spectra turn out to be very sensitive to the zeros of the dielectric function along the quantum-well growth direction and, therefore, allow to identify the resonances associated with the Z exciton-polariton mode. We demonstrate that 45° reflectometry could be a powerful tool for studying Z exciton-polariton modes in near-surface quantum wells, which are difficult to observe in simple spectra of reflectivity Rp

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.

Large Rabi splitting in InGaN quantum wells microcavity at room temperature

2019 ◽  
Vol 6 (7) ◽  
pp. 076204
Author(s):  
JinZhao Wu ◽  
XiaoLing Shi ◽  
Hao Long ◽  
Lan Chen ◽  
LeiYing Ying ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Room Temperature ◽  
Rabi Splitting ◽  
Ingan Quantum Wells
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