Impact of piezoelectric fields on coherent zone-folded phonons in GaAs/AlAs superlattices

2019 ◽  
Vol 100 (12) ◽  
Author(s):  
Felix Mahler ◽  
Klaus Reimann ◽  
Michael Woerner ◽  
Thomas Elsaesser ◽  
Christos Flytzanis ◽  
...  
Keyword(s):  
Piezoelectric Fields

Reduction of oscillator strength due to piezoelectric fields inGaN/AlxGa1−xNquantum wells

1998 ◽  
Vol 57 (16) ◽  
pp. R9435-R9438 ◽  
Author(s):  
Jin Seo Im ◽  
H. Kollmer ◽  
J. Off ◽  
A. Sohmer ◽  
F. Scholz ◽  
...  
Keyword(s):  
Oscillator Strength ◽  
Piezoelectric Fields

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.

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 Enhancement of Photoemission on p-Type GaAs Using Surface Acoustic Waves

Sensors ◽  
2020 ◽  
Vol 20 (8) ◽  
pp. 2419
Author(s):  
Boqun Dong ◽  
Andrei Afanasev ◽  
Rolland Johnson ◽  
Mona Zaghloul
Keyword(s):  
Acoustic Waves ◽  
Surface Acoustic Waves ◽  
Device Fabrication ◽  
Effective Lifetime ◽  
Additional Layer ◽  
Carrier Recombination ◽  
Multiphysics Simulations ◽  
Current Voltage ◽  
Piezoelectric Fields ◽  
P Type

We demonstrate that photoemission properties of p-type GaAs can be altered by surface acoustic waves (SAWs) generated on the GaAs surface due to dynamical piezoelectric fields of SAWs. Multiphysics simulations indicate that charge-carrier recombination is greatly reduced, and electron effective lifetime in p-doped GaAs may increase by a factor of 10× to 20×. It implies a significant increase, by a factor of 2× to 3×, of quantum efficiency (QE) for GaAs photoemission applications, like GaAs photocathodes. Conditions of different SAW wavelengths, swept SAW intensities, and varied incident photon energies were investigated. Essential steps in SAW device fabrication on a GaAs substrate are demonstrated, including deposition of an additional layer of ZnO for piezoelectric effect enhancement, measurements of current–voltage (I–V) characteristics of the SAW device, and ability to survive high-temperature annealing. Results obtained and reported in this study provide the potential and basis for future studies on building SAW-enhanced photocathodes, as well as other GaAs photoelectric applications.

Influence of Spontaneous and Piezoelectric Polarizations on the Lattice Dynamics of III-Nitride Structures

2001 ◽  
Vol 680 ◽  
Author(s):  
Jérôme Gleize ◽  
Jean Frandon ◽  
Marie A. Renucci ◽  
Friedhelm Bechstedt
Keyword(s):  
Elasticity Theory ◽  
Lattice Dynamics ◽  
Effective Strain ◽  
Growth Direction ◽  
Stress And Strain ◽  
Free Standing ◽  
The Difference ◽  
Piezoelectric Fields ◽  
Nitride Layers ◽  
Theory Framework

ABSTRACTThe influence of pyroelectric and piezoelectric polarizations on the lattice dynamics of strained III-nitride based structures is investigated within a macroscopic framework. New relationships between stress and strain are derived, which take into account the piezoelectric fields, which appear in the strained III-nitride layers. Consequently, the strained phonon frequencies in such systems differ from those calculated within the elasticity theory framework. In the case of strained, free-standing GaN/AlN superlattices grown along the [0001] axis, the difference of the spontaneous polarizations of GaN and AlN also contributes to the change in the effective strain along the growth direction. The corresponding shift of the zone center phonon frequencies of GaN and AlN might be negligible or significant, depending on the value of the ratio of the GaN and AlN layer thickness.

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