ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

Electronic Resource

X-ray interference measurement of ultrathin semiconductor layers (1989)

Wie, C. R. ; Chen, J. C. ; Kim, H. M. ; [et al.]

Woodbury, NY : American Institute of Physics (AIP)

Applied Physics Letters 55 (1989), S. 1774-1776

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ISSN: 1077-3118

Source: AIP Digital Archive

Topics: Physics

Notes: We have characterized, using the interference structure in x-ray rocking curves, a single or double strained GaInP layer grown on an InP substrate. The measured GaInP layer thicknesses are 9±3 A(ring) and 107±3 A(ring) for the single strained layer samples and 7 A(ring)/50 A(ring) and 32 A(ring)/32 A(ring) for the double strained layer samples. The rocking curve results for the 107 A(ring) single-barrier sample and the 7 A(ring)/50 A(ring) double-barrier sample agreed well with the cross-section transmission electron microscopy data and the secondary-ion mass spectrometry data. The x-ray interference structure for the single strained barrier samples indicates the existence of many half-monolayer steps within the 1×1 mm2 x-ray beam spot at each GaInP/InP interface.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.102189

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2

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Increased peak current in AlAs/GaAs resonant tunneling structures with GaInAs emitter spacer (1992)

Choi, Y. W. ; Wie, C. R.

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 71 (1992), S. 1853-1859

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ISSN: 1089-7550

Source: AIP Digital Archive

Topics: Physics

Notes: Self-consistent simulation results are presented for the symmetric barrier AlAs/GaAs/AlAs resonant tunneling structures with a GaInAs emitter spacer well [Appl. Phys. Lett. 58, 1077 (1991)]. A simple model is used to handle the two-dimensional emitter accumulation electrons. These accumulation electrons below the emitter launching energy are treated as pseudo three-dimensional electrons, distributed continuously down to a certain minimum energy. With a proper choice of this bottom energy, a good agreement is achieved in the peak position between the simulation results and the experimental data. The best fit value of the bottom energy for the accumulated electrons was about 2/3ΔEc below the emitter conduction band edges for all diodes. Also, the simulation results could explain the systematic variation of the experimental peak current and voltage values as a function of the GaInAs spacer well depth. In order to provide a design guideline, the layer parameters were systematically varied and the simulation results on the peak current are presented. The peak current density is found to be most sensitive to the AlAs barrier thickness, especially to the emitter barrier thickness, and it is further increased by using an emitter spacer well. Based on our theoretical analyses, a 10-A(ring) AlAs double barrier and 50-A(ring) GaAs well with a 50-A(ring) Ga0.9In0.1As emitter spacer well could produce a peak current density as high as 2200 kA/cm2.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.351170

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3

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Electrical and structural study of partially relaxed Ga0.92In0.08As(p+)/ GaAs(n) diodes (1990)

Choi, Y. W. ; Wie, C. R. ; Evans, K. R. ; [et al.]

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 68 (1990), S. 1303-1309

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ISSN: 1089-7550

Source: AIP Digital Archive

Topics: Physics

Notes: The effects of in-plane lattice mismatch have been studied for Ga0.92In0.08As(p+)/GaAs(n)/GaAs(n+) diodes. Different in-plane mismatch at the p–n junction was introduced by a variation of the GaInAs layer thickness (h=0.1, 0.25, 0.5, and 1 μm). Capacitance-voltage (C-V) measurements with different frequencies show a higher-frequency dispersion for a greater lattice-mismatched sample. From the frequency dependence of the C-V curve, single-level charged interface-state density (Ns) was estimated using the effective parallel capacitance and conductance components. The average charged interface density Nss was also estimated using Voltage-intercept (Vint) method. Nss shows a linear dependence on the in-plane mismatch. The charged interface state density is approximately 2.7 Δa(parallel)/a30 for partially lattice-relaxed heterojunctions. For the 1 μm sample, the forward I-V characteristic shows quasi-Fermi level pinning effect. Admittance spectroscopy measurement gives an equilibrium Fermi energy at about Ev+0.36 eV with hole capture cross section cp=2.7×10−15 cm2 for the 1 μm sample and at Ev+0.21 eV and cp=2.4×10−16 cm2 for the 0.5 μm sample.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.346699

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4

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Shallow levels, deep levels and electrical characteristics in Zn-doped GaInP/InP (1990)

Chen, J. F. ; Chen, J. C. ; Lee, Y. S. ; [et al.]

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 67 (1990), S. 3711-3716

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ISSN: 1089-7550

Source: AIP Digital Archive

Topics: Physics

Notes: Zn-doped GaxIn1−xP epilayers grown by metalorganic chemical vapor deposition have been studied in a wide range of GaP mole fraction. The Zn distribution coefficient was studied as a function of alloy composition. With a constant flow rate of diethylzinc, a decreasing net hole concentration was observed with increasing GaP mole fraction. The I-V characteristics of Au on p-GaxIn1−xP Schottky diodes show a deviation from an ideal thermionic behavior as the lattice mismatch increases. This deviation was analyzed in terms of the shunt resistance which decreased exponentially with the mismatch. A dominant hole trap located at EV+0.84 eV was detected by deep-level transient spectroscopy in a Ga0.032In0.968P layer. The density of this hole trap significantly increases with increasing lattice mismatch.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.345011

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5

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Electric field measurements in an argon glow discharge using laser spectroscopy (1996)

Choi, Y. W. ; Bowden, M. D. ; Muraoka, K.

Woodbury, NY : American Institute of Physics (AIP)

Applied Physics Letters 69 (1996), S. 1361-1363

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ISSN: 1077-3118

Source: AIP Digital Archive

Topics: Physics

Notes: Direct measurements of the electric field in the sheath of a dc glow discharge were made using laser spectroscopic measurements of argon atoms. The effect of the electric field on the 4s⇒7f transitions was used to determine the electric field. Both laser opto-galvanic spectra and laser-induced fluorescence spectra were obtained. The magnitude of the electric field was determined using an experimentally obtained calibration of the change in wavelength produced by the electric field. © 1996 American Institute of Physics.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.117436

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6

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Measurements of sheath electric fields in a high pressure helium radio frequency discharge (1995)

Bowden, M. D. ; Choi, Y. W. ; Muraoka, K. ; [et al.]

Woodbury, NY : American Institute of Physics (AIP)

Applied Physics Letters 66 (1995), S. 1059-1061

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ISSN: 1077-3118

Source: AIP Digital Archive

Topics: Physics

Notes: The importance of capacitively coupled radio frequency (rf) discharges has resulted in many attempts, by experiment and by simulation, to understand the dynamics of the discharge. Because of the time varying nature of the sheath potential, the sheath region is of special interest in these plasmas. Direct measurements are reported of the sheath electric fields in a helium plasma obtained using a laser induced fluorescence method. In the interpretation of these measurements, the time dependence of the fluorescence spectrum had to be considered. The measured electric field distributions can be used to deduce sheath widths. © 1995 American Institute of Physics.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.113573

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7

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Designing resonant tunneling structures for increased peak current density (1991)

Wie, C. R. ; Choi, Y. W.

Woodbury, NY : American Institute of Physics (AIP)

Applied Physics Letters 58 (1991), S. 1077-1079

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ISSN: 1077-3118

Source: AIP Digital Archive

Topics: Physics

Notes: We report a simple method to increase the peak current density in a double-barrier resonant tunneling structure by using a small band-gap emitter spacer layer. We have fabricated AlAs/GaAs/AlAs resonant tunneling structures using a Ga1−xInxAs spacer layer in the emitter. The peak current density was increased systematically with the increasing indium content by a factor ranging from 2.5 at x=0.05 to 5 at x=0.2 from the value at x=0. The increased peak current density was accompanied by increases in the peak voltage and peak-to-valley ratio. The lowering of the bottom of electron energy distribution in the GaInAs emitter spacer layer is shown to explain both the peak current and voltage increases. In the sequential tunneling picture, the peak current increases because of the increase in the number of resonant electrons which occurs if the bottom of energy distribution is lowered. We also report for the first time a strong bistability in the current-voltage characteristics at T≤240 K in the asymmetric spacer layer structure (GaInAs emitter, GaAs collector) in an otherwise symmetric structure.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.104376

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8

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Separation and Preconcentration of Strontium from Calcium in Aqueous Samples by Supported Liquid Membrane Containing Crown Ether (2000)

Lee, C. W. ; Hong, K. H. ; Lee, M. H. ; [et al.]

Springer

Journal of radioanalytical and nuclear chemistry 243 (2000), S. 767-773

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ISSN: 1588-2780

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering

Notes: Abstract Supported liquid membrane containing crown ether (DC18C6) and dinonylnaphthalenesulfonic acid (DNNS) is proposed for separation and preconcentration of strontium in an aqueous environmental sample. The effects of carriers in membrane on permeability and selectivity of Sr2+ were characterized. Crown ether has a key role in the selective transport of strontium ion while DNNS facilitates the transport of both Sr2+ and Ca2+. A strontium ion can be selectively transported to an acidic strip solution against its concentration gradient across the membrane. This SLM can be used as an efficient method for separation and preconcentration of strontium in a neutral aqueous sample.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1010655311078

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