31. |
Spontaneous lateral alignment ofIn0.25Ga0.75Asself-assembled quantum dots on (311)B GaAs grown by gas source molecular beam epitaxy |
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Applied Physics Letters,
Volume 70,
Issue 26,
1997,
Page 3579-3581
Kenichi Nishi,
Takayoshi Anan,
Akiko Gomyo,
Shigeru Kohmoto,
Shigeo Sugou,
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摘要:
Spontaneous lateral alignment was observed in InGaAs quantum dots formed by self-assembly on (311)B GaAs by gas source molecular beam epitaxy. The alignment occurred in a direction inclined about 60° from the [011] direction on a (3-11) [(311)B] surface. A typical base diameter of the dots was about120±10 nm.The heights varied from 3 to 13 nm as the nominal thickness of the InGaAs layer increased from 4 to 8 nm. The formation mechanism for the alignment is studied based on the growth thickness dependence of the dot structures. A photoluminescence linewidth of 24 meV was obtained from 9 nm high dots at 77 K, indicating the formation of a uniform dot structure. ©1997 American Institute of Physics.
ISSN:0003-6951
DOI:10.1063/1.119239
出版商:AIP
年代:1997
数据来源: AIP
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32. |
Subband electron densities of Si &dgr;-doped pseudomorphicIn0.2Ga0.8As/GaAsheterostructures |
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Applied Physics Letters,
Volume 70,
Issue 26,
1997,
Page 3582-3584
G. Li,
A. Babinski,
C. Jagadish,
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摘要:
Magnetotransport properties of Si &dgr;-doped pseudomorphicIn0.2Ga0.8As/GaAsheterostructures grown by metalorganic vapor phase epitaxy have been investigated in magnetic fields up to 12 T in the dark at 1.7 K. Different &dgr;-doping configurations, in which the same Si &dgr;-doped layer was placed at different positions with respect to theIn0.2Ga0.8Aswell, have been studied to clarify their effect on subband electron densities in the well. Very high electron densities of>4×1012 cm−2were obtained when placing a Si &dgr;-doped layer at the well center or the well–barrier interface. We found that one subband was occupied in the well-center-doped structure, but when the Si &dgr;-doped layer was at the well–barrier interface, the second subband in the well became occupied. The electron density of Si &dgr;-modulation-dopedIn0.2Ga0.8As/GaAsheterostructures, in which the cap barrier or the buffer barrier was Si &dgr; doped, was in the order of<1.2×1012 cm−2.The Si &dgr; doping in both of the barriers led to an increase of the electron density by almost a factor of 2. Owing to an incomplete transfer of the electrons from the Si &dgr;-doped layers to the well, parallel conduction was observed in the Si &dgr;-modulation-doped structures. ©1997 American Institute of Physics.
ISSN:0003-6951
DOI:10.1063/1.119240
出版商:AIP
年代:1997
数据来源: AIP
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33. |
Evaluation of the CdS/CdTe interface using free-electron laser internal photoemission technique |
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Applied Physics Letters,
Volume 70,
Issue 26,
1997,
Page 3585-3587
Kazuhisa Nishi,
Hideaki Ohyama,
Toshiji Suzuki,
Tsuneo Mitsuyu,
Takio Tomimasu,
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摘要:
The CdS/CdTe interface was investigated by the free-electron laser (FEL) internal photoemission technique. This technique is based on photocurrent spectroscopy utilizing the tunability and intense peak power of the FEL operative in the infrared range. We found two thresholds in the photocurrent spectrum, which can be identified as steplike band discontinuities. It is demonstrated that there is a mixed crystal layer ofCdS1−xTexat the CdS/CdTe interface. ©1997 American Institute of Physics.
ISSN:0003-6951
DOI:10.1063/1.119241
出版商:AIP
年代:1997
数据来源: AIP
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34. |
Probing of InAs/AlSb double barrier heterostructures by ballistic electron emission spectroscopy |
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Applied Physics Letters,
Volume 70,
Issue 26,
1997,
Page 3588-3590
J. Walachova´,
J. Zelinka,
J. Vanisˇ,
D. H. Chow,
J. N. Schulman,
S. Karamazov,
M. Cukr,
P. Zich,
J. Kra´l,
T. C. McGill,
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摘要:
InAs/AlSb resonant tunneling heterostructures have been studied by ballistic electron emission spectroscopy. Current thresholds attributed to quasibound states in the quantum well and emission over the AlSb barriers are observed. The observed shape of thresholds is consistent with inelastic processes in the InAs layers of the structures, where a high number of electron–hole pairs are generated. A threshold consistent with the generation of electron–hole pairs in quantum well states is observed. ©1997 American Institute of Physics.
ISSN:0003-6951
DOI:10.1063/1.119274
出版商:AIP
年代:1997
数据来源: AIP
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35. |
Fe-doped InGaAs/InGaAsP photorefractive multiple quantum well devices operating at 1.55 &mgr;m |
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Applied Physics Letters,
Volume 70,
Issue 26,
1997,
Page 3591-3593
C. De Matos,
A. Le Corre,
H. L’Haridon,
S. Gosselin,
B. Lambert,
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摘要:
Results on semi-insulating photorefractive multiple quantum well (MQW) devices operating without trapping layers are reported. The device structure consists of a MQW doped with Fe(1017 cm−3)isolated from the doped contact by intrinsic standoff layers. The photocarriers generated by the pump pulse are trapped in the MQW and screen the applied electric field in the MQW. Output diffraction efficiency of 0.2&percent; is measured in a nondegenerate four-wave-mixing configuration and the rise time of the diffraction signal reaches 200 ns. ©1997 American Institute of Physics.
ISSN:0003-6951
DOI:10.1063/1.119242
出版商:AIP
年代:1997
数据来源: AIP
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36. |
Thermally stimulated luminescence from x-irradiated porous silicon |
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Applied Physics Letters,
Volume 70,
Issue 26,
1997,
Page 3594-3596
D. W. Cooke,
B. L. Bennett,
E. H. Farnum,
W. L. Hults,
R. E. Muenchausen,
J. L. Smith,
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摘要:
We have measured thermally stimulated luminescence from light-emitting porous silicon that has been x irradiated at room temperature and heated to 400 °C. The glow curve exhibits peaks at 103, 155, 219, and 271 °C, with additional maxima occurring above 400 °C. Each of the peaks emits similar emission spectra characterized by a band with a maximum near 720 nm and 0.39 eV full width at half-maximum. Following x irradiation at room temperature, the sample exhibits well-known photoluminescence, but after heating to 400 °C, the loss of hydrogen renders the sample nonphotoluminescent. However, thermally stimulated luminescence can be repeatedly induced. Observation of thermally stimulated luminescence is unambiguous evidence for the existence of an insulating surface layer on porous silicon. ©1997 American Institute of Physics.
ISSN:0003-6951
DOI:10.1063/1.119243
出版商:AIP
年代:1997
数据来源: AIP
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37. |
Photoluminescence study of implantation dose and dose-rate dependence of Si doping of GaAs |
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Applied Physics Letters,
Volume 70,
Issue 26,
1997,
Page 3597-3599
M. Kotani,
M. Zafar Iqbal,
Y. Makita,
R. Morton,
S. S. Lau,
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摘要:
Photoluminescence spectroscopy is used to investigate some of the recently reported effects of implantation dose and dose rate on the electrical activation of Si dopant in GaAs. Two new luminescence bands are observed to emerge in our spectra with the increasing Si dose at doses(∼2×1013 cm−2)where the carrier concentration is known to saturate. The higher energy band at the∼840–880 nmwavelength shows a more pronounced rise in strength with increase in dose rate from3 nA/cm2beam current density to60 nA/cm2.The deep-level luminescence band extending from∼1000to∼1600 nmwavelength dominates the spectra for both the low-dose-rate and high-dose-rate samples above a dose of∼2×1013 cm−2.The observed rapid generation of type-I dislocations above this dose suggests this band is related to some impurity Cottrell atmospheres around the dislocations in GaAs. ©1997 American Institute of Physics.
ISSN:0003-6951
DOI:10.1063/1.119244
出版商:AIP
年代:1997
数据来源: AIP
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38. |
Carbon doping and etching ofAlxGa1−xAs(0⩽x⩽1)with carbon tetrachloride in metalorganic vapor phase epitaxy |
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Applied Physics Letters,
Volume 70,
Issue 26,
1997,
Page 3600-3602
H. Q. Hou,
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摘要:
Carbon doping and the parasitic growth-rate reduction with carbon-tetrachloride(CCl4)inAlxGa1−xAswas studied in the entire Al composition range for metalorganic vapor phase epitaxial growth. The doping efficiency in AlGaAs was found to increase by two orders of magnitude when the Al composition inAlxGa1−xAschanged from 0 to 1. The parasitic growth rate reduction, however, decreased by a factor of 15 whenxchanged from 0 to 1. This reduction of growth rate was confirmed to be caused by the etching of the material from the surface by Cl radicals cracked fromCCl4.This strong compositional selectivity of the doping and etching has potential implications for lateral definition of growth on patterned surfaces. The doping and etching behaviors were also studied as a function of the growth temperature. ©1997 American Institute of Physics.
ISSN:0003-6951
DOI:10.1063/1.119245
出版商:AIP
年代:1997
数据来源: AIP
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39. |
Overdamped Josephson junctions withNb/AlOx/Al/AlOx/Nbstructure for integrated circuit application |
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Applied Physics Letters,
Volume 70,
Issue 26,
1997,
Page 3603-3605
Masaaki Maezawa,
Akira Shoji,
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摘要:
We present characteristics of overdamped Josephson junctions consisting ofNb/AlOx/Al/AlOx/Nbstructures. The junctions were fabricated using a well-developedNb/AlOx/Nb-junction technology and showed well-defined Josephson characteristics at 4.2 K. The characteristic voltageVc[the product of the critical currentIcand the effective normal resistanceRn(eff)] of junctions, which determines high-frequency performance of the junction, was in the range of 0.1–0.5 mV, and the critical current densityJcin the range of102–104 A/cm2.Maximum-to-minimum variations inIcover a wafer were±4&percent;for junctions withVc=0.15 mVand±13&percent;for junctions withVc=0.5 mV.©1997 American Institute of Physics.
ISSN:0003-6951
DOI:10.1063/1.119246
出版商:AIP
年代:1997
数据来源: AIP
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40. |
Domain-orientation dependence of levitation force in seeded melt grown single-domainYBa2Cu3Ox |
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Applied Physics Letters,
Volume 70,
Issue 26,
1997,
Page 3606-3608
Donglu Shi,
D. Qu,
S. Sagar,
K. Lahiri,
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摘要:
Domain-orientation dependence of levitation force has been determined for single-domainYBa2Cu3Ox.The single-domain material is obtained from a seeded melt growth process. The levitation force has been found to reach a maximum as thecaxis of the domain is parallel to the direction of the force. The levitation force decreases in a cosine law fashion as the angle &thgr; (the angle between the direction of the force and thecaxis) increases from 0° to 60°. A maximum anisotropy of levitation force of 2.29 has been found. A physical model is proposed to explain the observed orientation dependence. ©1997 American Institute of Physics.
ISSN:0003-6951
DOI:10.1063/1.119247
出版商:AIP
年代:1997
数据来源: AIP
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