Limiting factors of room-temperature nonradiative photoluminescence lifetime in polar and nonpolar GaN studied by time-resolved photoluminescence and slow positron annihilation techniques

2005 ◽  
Vol 86 (2) ◽  
pp. 021914 ◽  
Author(s):  
S. F. Chichibu ◽  
A. Uedono ◽  
T. Onuma ◽  
T. Sota ◽  
B. A. Haskell ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Room Temperature ◽  
Limiting Factors ◽  
Time Resolved ◽  
Slow Positron ◽  
Photoluminescence Lifetime ◽  
Time Resolved Photoluminescence ◽  
Nonpolar Gan

scholarly journals Влияние условий роста и уровня легирования на кинетику люминесценции слоев Ge : Sb, выращенных на кремнии

2020 ◽  
Vol 54 (7) ◽  
pp. 685
Author(s):  
Д.В. Юрасов ◽  
Н.А. Байдакова ◽  
А.Н. Яблонский ◽  
А.В. Новиков
Keyword(s):  
Doping Level ◽  
Room Temperature ◽  
Carrier Lifetime ◽  
Growth Conditions ◽  
Published Data ◽  
Rapid Thermal Anneal ◽  
Time Resolved ◽  
Light Emitting ◽  
Pl Intensity ◽  
Time Resolved Photoluminescence

Light-emitting properties of Ge-on-Si(001) layers doped by Sb were studied by stationary and time-resolved photoluminescence (PL) at room temperature. It was obtained that the PL intensity of n-Ge/Si(001) structures is maximized when the doping level is close to the equilibrium solubility of Sb in Ge (~1019 cm-3) which is in accordance with the previously published data. Time-resolved studies of the direct-related PL signal have shown that both the donor density and the growth conditions of doped layer, in particular, the growth temperature influence the PL kinetics. It was obtained that the increase of doping level leads to the decrease of the characteristic carrier lifetime. Moreover, usage of low growth temperatures which is needed to form the doped n-Ge layers also results in shortening of the carrier lifetime as compared with Ge layers grown at high temperatures. It was found that rapid thermal anneal at proper conditions could partially compensate the above mentioned detrimental effects and lead to the increase of both the PL intensity and carrier lifetime.

scholarly journals Excited-State Dynamics of Room-Temperature Phosphorescent Organic Materials Based on Monobenzil and Bisbenzil Frameworks

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3904
Author(s):  
Kaveendra Maduwantha ◽  
Shigeyuki Yamada ◽  
Kaveenga Rasika Koswattage ◽  
Tsutomu Konno ◽  
Takuya Hosokai
Keyword(s):  
Excited State ◽  
Density Functional ◽  
Room Temperature ◽  
Photophysical Properties ◽  
Density Functional Theory Calculations ◽  
Time Resolved ◽  
Excited State Dynamics ◽  
Unique Material ◽  
Potential Applications ◽  
Time Resolved Photoluminescence

Room-temperature phosphorescent (RTP) materials have been attracting tremendous interest, owing to their unique material characteristics and potential applications for state-of-the-art optoelectronic devices. Recently, we reported the synthesis and fundamental photophysical properties of new RTP materials based on benzil, i.e., fluorinated monobenzil derivative and fluorinated and non-fluorinated bisbenzil derivative analogues [Yamada, S. et al., Beilstein J. Org. Chem. 2020, 16, 1154–1162.]. To deeply understand their RTP properties, we investigated the excited-state dynamics and photostability of the derivatives by means of time-resolved and steady-state photoluminescence spectroscopies. For these derivatives, clear RTP emissions with lifetimes on the microsecond timescale were identified. Among them, the monobenzil derivative was found to be the most efficient RTP material, showing both the longest lifetime and highest amplitude RTP emission. Time-resolved photoluminescence spectra, measured at 77 K, and density functional theory calculations revealed the existence of a second excited triplet state in the vicinity of the first excited singlet state for the monobenzil derivative, indicative of the presence of a fast intersystem crossing pathway. The correlation between the excited state dynamics, emission properties, and conformational flexibility of the three derivatives is discussed.

Epitaxial Growth and Luminescence Characterization of Si-based Double Heterostructures Light-emitting Diodes with Iron Disilicide Active Region

2006 ◽  
Vol 958 ◽  
Author(s):  
Takashi Suemasu ◽  
Cheng Li ◽  
Tsuyoshi Sunohara ◽  
Yuta Ugajin ◽  
Ken'ichi Kobayashi ◽  
...  
Keyword(s):  
Decay Time ◽  
Room Temperature ◽  
Time Resolved ◽  
Iron Disilicide ◽  
Light Emitting ◽  
Si Substrates ◽  
Carrier Recombination ◽  
Double Heterostructures ◽  
Time Resolved Photoluminescence

ABSTRACTWe have epitaxially grown Si/β-FeSi2/Si (SFS) structures with β-FeSi2 particles or β-FeSi2 continuous films on Si substrates by molecular beam epitaxy (MBE), and observed 1.6 μm electroluminescence (EL) at room temperature (RT). The EL intensity increases with increasing the number of β-FeSi2 layers. The origin of the luminescence was discussed using time-resolved photoluminescence (PL) measurements. It was found that the luminescence originated from two sources, one with a short decay time (τ∼10 ns) and the other with a long decay time (τ∼100 ns). The short decay time was due to carrier recombination in β-FeSi2, whereas the long decay time was due probably to a defect-related D1 line in Si.

Excitation-Wavelength Dependent and Time-Resolved Photoluminescence Studies of Europium Doped GaN Grown by Interrupted Growth Epitaxy (IGE)

2005 ◽  
Vol 866 ◽  
Author(s):  
Ei Ei Nyein ◽  
Uwe Hömmerich ◽  
Chanaka Munasinghe ◽  
Andrew J. Steckl ◽  
John M. Zavada
Keyword(s):  
Room Temperature ◽  
Growth Conditions ◽  
Excitation Wavelength ◽  
Time Resolved ◽  
Pl Intensity ◽  
Photoluminescence Studies ◽  
Two Peaks ◽  
Time Resolved Photoluminescence ◽  
Cycling Time ◽  
The Eu

AbstractThe emission properties of Eu doped GaN thin films prepared by interrupted growth epitaxy (IGE) were investigated through excitation-wavelength dependent and time-resolved photoluminescence (PL) studies. Under above-gap excitation (333-363 nm) large differences were observed in the Eu3+ PL intensity and spectral features as a function of Ga shutter cycling time. The overall strongest red Eu3+ PL intensity was obtained from a sample grown with a Gashutter cycling time of 20 minutes. The main Eu3+ emission line originating from 5D0→ 7F2 transition was composed of two peaks located at 620 nm and 622 nm, which varied in relative intensity depending on the growth conditions. The room-temperature emission lifetimes of the samples were non-exponential and varied from ∼50 νs to ∼200 νs (1/e lifetimes). Under resonant excitation at 471 nm (7F0→5D2) all samples exhibited nearly identical PL spectra independent of Ga shutter cycling time. Moreover, the Eu3+ PL intensities and lifetimes varied significantly less compared to above-gap excitation. The excitation wavelengths dependent PL results indicate the existence of different Eu3+ centers in GaN: Eu, which can be controlled by the Ga shutter cycling time.

scholarly journals Room-Temperature Time–Resolved Photoluminescence Studies of UV Emission from GaN/AlN Quantum Wells

2002 ◽  
Vol 743 ◽  
Author(s):  
Madalina Furis ◽  
Fei Chen ◽  
Alexander N. Cartwright ◽  
Hong Wu ◽  
William J. Schaff
Keyword(s):  
Quantum Wells ◽  
Room Temperature ◽  
Spatial Separation ◽  
Multiple Quantum ◽  
Carrier Injection ◽  
Time Resolved ◽  
Uv Emission ◽  
Time Resolved Photoluminescence ◽  
Temperature Time ◽  
Ir Light

ABSTRACTRoom temperature time-resolved photoluminescence (TRPL) studies of multiple quantum well (MQW) structures of the binaries GaN and AlN grown by molecular beam epitaxy are reported. The eventual application of these structures is for GaN intersubband IR light emitters. However, as an initial study, the structures are evaluated at UV to investigate materials parameters relevant to IR light emission. The nominally 0.9, 1.3 and 1.5 nm GaN quantum wells are clad by 6nm of AlN on top of a thick AlN buffer grown on sapphire. All samples consisted of 20 quantum wells. The observed peak energy of the emission spectrum is in excellent agreement with a model that includes the strong confinement present in these structures and the existence of the large built-in piezoelectric field and spontaneous polarization present inside the wells. Furthermore, consistent with screening of the in-well field as carriers are injected in the well, a clear blue shift of the emission is observed at short times after carrier injection. Subsequently, as the carriers recombine, the peak emission red-shifts and the screening of the field is reduced. Moreover, the observed lifetimes were energy dependent as should be expected from field dependent elongation of lifetimes due to spatial separation of the injected carriers. Specifically, the decay time at high energies can be fitted by a stretched exponential with a beta value of 0.8 which is consistent with carrier spatial separation. The lifetimes obtained from the fitting are of the order of 1ns, longer than the reported recombination lifetimes in similar GaN/AlGaN MQW's. On the low energy side of the PL feature the intensity time decay becomes exponential with lifetimes ranging from 3 to 10ns. The strong UV emission at room temperature makes these structures promising for UV emitters.

scholarly journals Фотолюминесценция с временным разрешением наноструктур InGaAs различной квантовой размерности

2019 ◽  
Vol 53 (11) ◽  
pp. 1520
Author(s):  
А.М. Надточий ◽  
С.А. Минтаиров ◽  
Н.А. Калюжный ◽  
М.В. Максимов ◽  
Д.А. Санников ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Quantum Well ◽  
Single Photon ◽  
Photon Counting ◽  
Dimensional Structure ◽  
Time Resolved ◽  
Single Photon Counting ◽  
Gaas Substrates ◽  
Photoluminescence Lifetime ◽  
Time Resolved Photoluminescence

By using time-correlated single-photon counting time-resolved photoluminescence of quantum-sized heterostructures of different dimensionality was investigated. InGaAs quantum dots, quantum well, and transitionally-dimensional structure — quantum well-dots were grown on GaAs substrates. It was observed, that photoluminescence decay strongly depends on structure dimensionality resulting in decay value of 6,7, and more than 20 ns for quantum dots, well-dots and well, respectively. As we believe localization centers in heterostructures may be responsible for such shortening of photoluminescence lifetime.

scholarly journals Time-Resolved Spectroscopy of InGaN

2000 ◽  
Vol 5 (S1) ◽  
pp. 803-809
Author(s):  
Milan Pophristic ◽  
Frederick H. Long ◽  
Chuong Tran ◽  
Ian T. Ferguson
Keyword(s):  
Quantum Dots ◽  
Time Scale ◽  
Room Temperature ◽  
Average Distance ◽  
Time Resolved ◽  
Light Emitting ◽  
Potential Fluctuations ◽  
Stretched Exponential ◽  
Time Resolved Photoluminescence ◽  
Kinetics Of

We have used time-resolved photoluminescence (PL), with 400 nm (3.1 eV) excitation, to examine InxGa1−xN/GaN light-emitting diodes (LEDs) before the final stages of processing at room temperature. We have found dramatic differences in the time-resolved kinetics between dim, bright and super bright LED devices. The lifetime of the emission for dim LEDs is quite short, 110 ± 20 ps at photoluminescence (PL) maximum, and the kinetics are not dependent upon wavelength. This lifetime is short compared to bright and super bright LEDs, which we have examined under similar conditions. The kinetics of bright and super bright LEDs are clearly wavelength dependent, highly non-exponential, and are on the nanosecond time scale (lifetimes are in order of 1 ns for bright and 10 ns for super bright LED at the PL max). The non-exponential PL kinetics can be described by a stretched exponential function, indicating significant disorder in the material. Typical values for β, the stretching coefficient, are 0.45 − 0.6 for bright LEDs, at the PL maxima at room temperature. We attribute this disorder to indium alloy fluctuations.From analysis of the stretched exponential kinetics we estimate the potential fluctuations to be approximately 75 meV in the super bright LED. Assuming a hopping mechanism, the average distance between indium quantum dots in the super bright LED is estimated to be 20 Å.

Sign in / Sign up

Export Citation Format

Share Document