Persistent Photoconductivity in n-Type GaN

1996 ◽  
Vol 449 ◽  
Author(s):  
A. E. Wickenden ◽  
G. Beadie ◽  
D. D. Koleske ◽  
W. S. Rabinovich ◽  
J. A. Freitas
Keyword(s):  
Room Temperature ◽  
Deep Level ◽  
Persistent Photoconductivity ◽  
Acceptor Pair ◽  
Deep Level Defect ◽  
Sapphire Substrates ◽  
Defect Centers ◽  
Donor Acceptor ◽  
Si Doped ◽  
Donor Acceptor Pair

ABSTRACTPersistent photoconductivity has been observed in n-type Si-doped GaN grown on sapphire substrates by metalorganic vapor phase epitaxy. The effect has been seen both in films which are of electrically high quality, based on low temperature photoluminescence (PL) and Hall analysis, and in films which either appear to be compensated or which exhibit strong donor-acceptor pair recombination. The photoconductivity has been observed to persist for several days at room temperature (300K). Modeling of the resistance recovery by a stretched exponential treatment may suggest a distribution of deep level defect centers in the Si-doped GaN films.

Deep Donor-Acceptor Pair Luminescence in Codoped GaN

2002 ◽  
Vol 743 ◽  
Author(s):  
Bing Han ◽  
Joel M. Gregie ◽  
Melville P. Ulmer ◽  
Bruce W. Wessels
Keyword(s):  
Luminescence Band ◽  
Room Temperature ◽  
Deep Level ◽  
Excitation Density ◽  
Acceptor Pair ◽  
Deep Donor ◽  
Donor Acceptor ◽  
Donor Acceptor Pair ◽  
Increasing Temperature ◽  
Luminescent Behavior

ABSTRACTDeep level defects formed in p-type GaN:Mg codoped with shallow donors have been investigated by photoluminescence (PL) spectroscopy. A donor-acceptor pair (DAP) luminescence band peaked at 2.45 eV dominates the room temperature PL spectrum in heavily codoped epilayers. A superlinear dependence of PL intensity on excitation density is observed for this band, with an exponent of 1.4∼1.7. The intensity of this band increases with increasing temperature with a maximum at 264K. To explain the luminescent behavior a DAP model was developed whereby the recombination involves a deep donor and shallow Mg acceptor. The deep donor is tentatively attributed to a DX center.

Mechanism of donor–acceptor pair recombination in Mg-doped GaN epilayers grown on sapphire substrates

1998 ◽  
Vol 84 (4) ◽  
pp. 2082-2085 ◽  
Author(s):  
T. W. Kang ◽  
S. H. Park ◽  
H. Song ◽  
T. W. Kim ◽  
G. S. Yoon ◽  
...  
Keyword(s):  
Acceptor Pair ◽  
Sapphire Substrates ◽  
Donor Acceptor ◽  
Donor Acceptor Pair ◽  
Mg Doped

Effects of Substrate Misorientation and the Growth Mechanism of Si Doped GaAs Grown on (111)A Substrate by MBE

1989 ◽  
Vol 160 ◽  
Author(s):  
Y. Okano ◽  
H. Seto ◽  
M. Shigeta ◽  
S. Nishine ◽  
I. Fujimoto ◽  
...  
Keyword(s):  
Growth Mechanism ◽  
Hole Concentration ◽  
Donor Site ◽  
Flux Ratio ◽  
Acceptor Pair ◽  
Mbe Growth ◽  
Donor Acceptor ◽  
Si Doped ◽  
Doping Mechanism ◽  
Donor Acceptor Pair

AbstractThe MBE growth of Si doped GaAs on slightly misoriented (111)A substrates was examined. The conduction types and the carrier concentrations were greatly affected by the degree of substrate misorientation. In the growth on an exactly (111)A oriented substrate, substantially all Si atoms acted as acceptors. With increase of the degree of misorientation and/or with increase of the flux ratio (JAs4/JGa), the number of donor-site Si atoms increased, that is, the hole concentration first decreased by autocompensation of Si and then the conductivity reversed from p-type to n-type. The photoluminescence of highly compensated (111)A films showed characteristics of donor-acceptor pair recombination. A doping mechanism including preferential decomposition of As4 molecules at the steps was proposed.

High quantum efficiency of photoluminescence in GaN and ZnO

2005 ◽  
Vol 892 ◽  
Author(s):  
Michael A. Reshchikov ◽  
Xing Gu ◽  
Bill Nemeth ◽  
Jeff Nause ◽  
Hadis Morkoç
Keyword(s):  
Quantum Efficiency ◽  
Molecular Beam ◽  
Shallow Donor ◽  
Nonradiative Recombination ◽  
Acceptor Pair ◽  
High Quantum Efficiency ◽  
Donor Acceptor ◽  
Si Doped ◽  
Donor Acceptor Pair ◽  
Zno Crystal

AbstractThe quantum efficiency (QE) of photoluminescence (PL) has been estimated in GaN and ZnO samples. A Si-doped GaN layer grown by molecular beam epitaxy (MBE) exhibited the highest QE of about 90% at low temperatures. Recombination via the shallow donor-acceptor pair transitions dominated in this sample. In contrast, a bulk ZnO crystal with the QE of PL of about 85% contained almost no defect- or impurity-related PL signatures besides the emission attributed to free and bound excitons. The sources of radiative and nonradiative recombination in GaN and ZnO are discussed.

Time Resolved Photoluminescence Spectroscopy on GaN Epitaxial Layers

1995 ◽  
Vol 378 ◽  
Author(s):  
B. K. Meyer ◽  
D. Volm ◽  
C. Wetzel ◽  
L. Eckey ◽  
J.-Ch. Holst ◽  
...  
Keyword(s):  
Low Temperatures ◽  
Photoluminescence Spectroscopy ◽  
Epitaxial Layers ◽  
Acceptor Pair ◽  
Time Resolved ◽  
Sapphire Substrates ◽  
Donor Acceptor ◽  
Donor Acceptor Pair ◽  
Time Resolved Photoluminescence

AbstractFree and bound exciton luminescences as well as donor-acceptor pair recombination of GaN epitaxial layers on 6H-SiC and sapphire substrates were investigated using time integrated and time resolved photoluminescence measurements at low temperatures. Lifetimes are determined for the donor bound exciton at 3.4722eV and for two acceptor bound excitons with energies of 3.4672eV and 3.459eV. Luminescences between 3.29eV and 3.37eV are identified as due to excitons deeply bound to centers located near the substrate-epilayer interface.

Photoluminescence Study of p-ZnGeP2 Crystals

1996 ◽  
Vol 450 ◽  
Author(s):  
Yurri V. Rud ◽  
Vasilii Yu ◽  
M. C. Ohmer ◽  
P. G. Shunemann
Keyword(s):  
Low Temperature ◽  
Single Crystals ◽  
Room Temperature ◽  
Directed Crystallization ◽  
Acceptor Pair ◽  
Long Wavelength ◽  
Donor Acceptor ◽  
Donor Acceptor Pair ◽  
Nonlinear Devices ◽  
Conversion Efficiencies

ABSTRACTPhotoluminescence (PL) steady-state spectra of p-ZnGeP2 (ZGP) single crystals grown by high- and low-temperature directed crystallization have been investigated. It is determined that the long-wavelength component PL with a maximum in the interval 1.2–1.5 eV for different crystals quenched in the temperature range 77–300 K. The long-wavelength component PL are due to donor-acceptor pair transitions. At room temperature the short-wavelength PL with a maximum near 1.85 eV becomes the determining component. The nature of this band discussed. The use of low-temperature directed crystallization reduces the concentration of lattice defects in ZGP single crystals and opens up the new possibilities for increasing the conversion efficiencies of nonlinear devices.

Electroluminescence from Cu(In,Ga)Se2 Thin-film Solar Cells

2007 ◽  
Vol 1012 ◽  
Author(s):  
Thomas Kirchartz ◽  
Julian Mattheis ◽  
Uwe Rau
Keyword(s):  
Solar Cells ◽  
Room Temperature ◽  
Open Circuit Voltage ◽  
Light Emitting Diode ◽  
Open Circuit ◽  
Acceptor Pair ◽  
Transition Range ◽  
Light Emitting ◽  
Donor Acceptor ◽  
Donor Acceptor Pair

AbstractWe compare the electroluminescence (EL) of three polycrystalline ZnO/CdS/Cu(In,Ga)Se2 heterojunction solar cells with similar bandgaps but different open circuit voltages, indicating a difference in the electronic quality of the absorber. Temperature dependent electroluminescence measurements reveal that all cells feature transitions from donor-acceptor pair recombination at lower temperatures to band to band recombination at higher temperatures. However, the less efficient cells show a longer transition range with donor-acceptor pair recombination still apparent at room temperature. The thus broadened room temperature luminescence is one effect which reduces the open circuit voltage of the devices below the Shockley-Queisser-limit. The other effect is the existence of non-radiative recombination currents, which determine the efficiency of the device as light emitting diode. To quantify the open circuit voltage losses, we use reciprocity relations between electroluminescent and photovoltaic action of solar cells, which allow us to predict the light emitting diode efficiency. Measurements support the theory and show that Cu(In,Ga)Se2 solar cells reach external LED efficiencies approaching.

A New Deep Acceptor in Epitaxial Cubic SiC

1989 ◽  
Vol 162 ◽  
Author(s):  
J. A. Freitas ◽  
S. G. Bishop
Keyword(s):  
Thin Films ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Excitation Intensity ◽  
Acceptor Pair ◽  
Deep Acceptor ◽  
Intensity Dependence ◽  
Pl Spectra ◽  
Donor Acceptor ◽  
Donor Acceptor Pair

ABSTRACTThe temperature and excitation intensity dependence of photoluminescence (PL) spectra have been studied in thin films of SiC grown by chemical vapor deposition on Si (100) substrates. The low power PL spectra from all samples exhibited a donor-acceptor pair PL band which involves a previously undetected deep acceptor whose binding energy is approximately 470 meV. This deep acceptor is found in every sample studied independent of growth reactor, suggesting the possibility that this background acceptor is at least partially responsible for the high compensation observed in Hall effect studies of undoped films of cubic SiC.

scholarly journals Time-resolved Spectroscopy of the violet luminescence of undoped AlN

2005 ◽  
Vol 10 ◽  
Author(s):  
R. Freitag ◽  
K. Thonke ◽  
R. Sauer ◽  
D. G. Ebling ◽  
L. Steinke
Keyword(s):  
Epitaxial Layers ◽  
Yellow Luminescence ◽  
Acceptor Pair ◽  
Time Resolved ◽  
Time Resolved Spectroscopy ◽  
Violet Luminescence ◽  
Donor Acceptor ◽  
Violet Band ◽  
Donor Acceptor Pair

We report on the time-resolved luminescence of the defect-related violet band from undoped AlN epitaxial layers grown on sapphire and SiC. For both measurements in photoluminescence and in cathodoluminescence a decay of algebraic nature at long times is observed. This is typical for donor-acceptor pair transitions. We compare the behavior of this band to that of the generically yellow luminescence of GaN.

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