Auger Recombination in Antimony-Based, Strain-Balanced, Narrow-Band-Gap Superlattics

1997 ◽  
Vol 484 ◽  
Author(s):  
J. T. Olesberg ◽  
Thomas F. Boggess ◽  
S. A. Anson ◽  
D.-J. Jan ◽  
M. E. Flatté ◽  
...  
Keyword(s):  
Auger Recombination ◽  
Growth Direction ◽  
Bandgap Energy ◽  
Recombination Rates ◽  
Electron Hole ◽  
Time Resolved ◽  
All Optical ◽  
Semi Empirical ◽  
The Impact ◽  
Hole Recombination

AbstractTime-resolved all-optical techniques are used to measure the density and temperature dependence of electron-hole recombination in an InAs/GaInSb/InAs/AlGaInAsSb strain-balanced superlattice grown by molecular beam expitaxy on GaSb. This 4 μm bandgap structure, which has been designed for suppressed Auger recombination, is a candidate material for the active region of mid-infrared lasers. While carrier lifetime measurements at room temperature show unambiguous evidence of Auger recombination, the extracted Auger recombination rates are considerably lower than those reported for bulk materials of comparable bandgap energy. We find that the Auger rate saturates at carrier densities comparable to those required for degeneracy of the valence band, illustrating the impact of Fermi statistics on the Auger process. The measured results are compared with theoretical Auger rates computed using a band structure obtained from a semi-empirical 8-band K.p model. We find excellent agreement between theoretical and experimental results when Umklapp processes in the growth direction are included in the calculation. Measured recombination rates from 50 to 300 K are combined with calculated threshold carrier densities to determine a material To value for the superlattice.

scholarly journals En route to a unified model for photo-electrochemical reactor optimisation. I - Photocurrent and H2 yield predictions

2017 ◽  
Vol 5 (43) ◽  
pp. 22683-22696 ◽  
Author(s):  
Franky E. Bedoya-Lora ◽  
Anna Hankin ◽  
Geoff H. Kelsall
Keyword(s):  
Electrochemical Cell ◽  
Cell Model ◽  
Bubble Formation ◽  
Electrochemical Reactor ◽  
Photon Flux ◽  
Recombination Rates ◽  
Electron Hole ◽  
Gas Desorption ◽  
H2 Yield ◽  
Hole Recombination

A photo-electrochemical cell model was developed accounting for photon flux, electron–hole recombination rates, gas desorption, bubble formation and cross-over losses.

EXCITONIC SIDE BANDS OF INNER-SHELL EXCITATIONS IN RARE GAS SOLIDS

2002 ◽  
Vol 09 (02) ◽  
pp. 1333-1338 ◽  
Author(s):  
S. VIELHAUER ◽  
M. KIRM ◽  
V. KISAND ◽  
E. NEGODIN ◽  
E. SOMBROWSKI ◽  
...  
Keyword(s):  
Free Exciton ◽  
Rare Gas ◽  
Excitation Threshold ◽  
Energy Position ◽  
Excitation Spectra ◽  
Electron Hole ◽  
Time Resolved ◽  
Ionization Limit ◽  
Time Resolved Photoluminescence ◽  
Hole Recombination

Valence-exciton luminescence under inner-shell excitation of the rare gas solids Xe, Kr, and Ar has been measured using time-resolved photoluminescence. Two different processes for exciton creation can be distinguished: creation of "prompt" excitons immediately after excitation (within the experimental time resolution), and creation of "delayed" excitons through electron–hole recombination. The decay structure of the exciton emission in the range of inner-shell excitation is characterized by the coexistence of the two processes. Time-resolved excitation spectra near the 2p edge in Ar, the 3d edge in Kr, and the 4d edge in Xe are discussed. The process of prompt exciton creation is strongly enhanced above an excitation threshold at the energy position of the ionization limit of the core state plus the energy of the valence free exciton.

Accumulation of Deep Traps at Grain Boundaries in Halide Perovskites

2019 ◽  
Author(s):  
Ji-Sang Park ◽  
Joaquín Calbo ◽  
Young-Kwang Jung ◽  
lucy whalley ◽  
Aron Walsh
Keyword(s):  
Grain Boundaries ◽  
Perovskite Solar Cells ◽  
Extended Defects ◽  
Trap States ◽  
Bulk Crystals ◽  
Recombination Rates ◽  
Electron Hole ◽  
Interstitial Defects ◽  
Halide Perovskites ◽  
Hole Recombination

<div> <div> <div> <p>The behaviour of grain boundaries in polycrystalline halide perovskite solar cells remains poorly understood. Whereas theoretical studies indicate that grain boundaries are not active for electron-hole recombination, there have been observations of higher non-radiative recombination rates involving these extended defects. We find that iodine interstitial defects, which have been established as a recombination center in bulk crystals, tend to segregate at planar defects in CsPbI3. First-principles calculations show that enhanced structural relaxation of the defects at grain boundaries results in increased stability (higher concentration) and deeper trap states (faster recombination). We show how the grain boundary can be partly passivated by halide mixing or extrinsic doping, which replaces or suppresses the formation of trap states close to the grain boundaries.<br></p> </div> </div> </div>

Optical Properties of Ingan/GaN Multi Quantum Well Structures

1997 ◽  
Vol 482 ◽  
Author(s):  
J. P. Bergman ◽  
N. Saksulv ◽  
J. Dalfors ◽  
P. O. Holtz ◽  
B. Monemar ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Multiple Quantum ◽  
Recombination Rates ◽  
Energy Position ◽  
Electron Hole ◽  
Time Resolved ◽  
Quantum Well Structures ◽  
Lower Energy Band ◽  
Time Resolved Photoluminescence ◽  
Multi Quantum Well

AbstractA set of GaN/InGaN multiple quantum wells (QWs) with well thickness 30 Å and barrier thickness 60 Å were grown by MOCVD on sapphire substrates. The n-type Si doping of the InGaN QWs was varied, in order to produce a different electron concentration in the QWs for the different samples. Optical spectra were obtained by time resolved photoluminescence spectroscopy. The data show weak excitonic spectra from the QWs as well as a broad deeper emission with a much stronger intensity. The spectral shape becomes narrower and the energy position shifts to higher energies with increasing doping. The two different emissions are not easily separated in CW or time integrated spectra, but are clearly observed in a time resolved spectral measurement due to their different recombination rates. The deeper emission has a long and non-exponential decay, with an average decay time in the order of several hundred nanoseconds. The higher energy exciton emission has a much faster decay of about 1 ns. The lower energy band is tentatively explained as due to separately localized electron-hole (e-h) pairs in the QW.

Accumulation of Deep Traps at Grain Boundaries in Halide Perovskites

2019 ◽  
Author(s):  
Ji-Sang Park ◽  
Joaquín Calbo ◽  
Young-Kwang Jung ◽  
lucy whalley ◽  
Aron Walsh
Keyword(s):  
Grain Boundaries ◽  
Perovskite Solar Cells ◽  
Extended Defects ◽  
Trap States ◽  
Bulk Crystals ◽  
Recombination Rates ◽  
Electron Hole ◽  
Interstitial Defects ◽  
Halide Perovskites ◽  
Hole Recombination

<div> <div> <div> <p>The behaviour of grain boundaries in polycrystalline halide perovskite solar cells remains poorly understood. Whereas theoretical studies indicate that grain boundaries are not active for electron-hole recombination, there have been observations of higher non-radiative recombination rates involving these extended defects. We find that iodine interstitial defects, which have been established as a recombination center in bulk crystals, tend to segregate at planar defects in CsPbI3. First-principles calculations show that enhanced structural relaxation of the defects at grain boundaries results in increased stability (higher concentration) and deeper trap states (faster recombination). We show how the grain boundary can be partly passivated by halide mixing or extrinsic doping, which replaces or suppresses the formation of trap states close to the grain boundaries.<br></p> </div> </div> </div>

Photoelectrochemical performance and ultrafast dynamics of photogenerated electrons and holes in highly titanium-doped hematite

2020 ◽  
Vol 22 (46) ◽  
pp. 27450-27457
Author(s):  
Alexander T. Paradzah ◽  
Kelebogile Maabong-Tau ◽  
Mmantsae Diale ◽  
Tjaart P. J. Krüger
Keyword(s):  
Ultrafast Dynamics ◽  
Recombination Rates ◽  
Photoelectrochemical Performance ◽  
Electron Hole ◽  
Photogenerated Electrons ◽  
Hole Recombination

We present electron–hole recombination rates in improved hematite photoelectrodes containing pseudobrookite and titania overlayers due to high doping.

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