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9 Aug 1993

Volume 63, Issue 6, pp. 709-852

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Space‐charge effects in photovoltaic double barrier quantum well infrared detectors

H. Schneider, E. C. Larkins, J. D. Ralston, K. Schwarz, F. Fuchs, and P. Koidl

Appl. Phys. Lett. 63, 782 (1993); http://dx.doi.org/10.1063/1.109906 (3 pages) | Cited 15 times

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We show that the spatial distribution of the dopants strongly influences the transport asymmetry and the photovoltage observed in double barrier quantum well intersubband photodetectors. This influence can be quantitatively explained by the local space‐charge fields arising from an asymmetry of the doping profile with respect to the well centers. The resulting transport model correctly predicts both the observed transport asymmetry of the photocurrent and the opposite asymmetry of the dark current.
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73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.50.Pz Photoconduction and photovoltaic effects
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
85.60.Gz Photodetectors (including infrared and CCD detectors)

Spectral behavior of solar cells based on the ‘‘junction near local defect layer’’ design

C. Summonte, M. Biavati, E. Gabilli, R. Galloni, S. Guerri, R. Rizzoli, and F. Zignani

Appl. Phys. Lett. 63, 785 (1993); http://dx.doi.org/10.1063/1.109907 (3 pages) | Cited 8 times

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The junction near local defect layer (JNLD) solar cell design [Li et al., Appl. Phys. Lett. 60, 2240 (1992)] was recently shown to greatly increase the short circuit current of silicon solar cells. The proposed mechanism is an enhancement of sub‐band‐gap light absorption through gap states, introduced by the presence of a defect layer situated in the junction region. Our measurements of JNLD solar cells evidence a change in the absorption spatial profile due to the defect layer. The result is a small enhancement in quantum efficiency in the visible red side of the spectrum that is in turn balanced by a recombination effect caused by the same defect layer, so that the final short circuit current does not increase. On the contrary, we detected a 20% decrease in the open circuit voltage that is attributed to the shorting effect of defect levels in the junction region. No sub‐band‐gap light absorption increase is detected.
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84.60.Jt Photoelectric conversion
78.30.-j Infrared and Raman spectra
78.40.Fy Semiconductors
71.55.Cn Elemental semiconductors
72.40.+w Photoconduction and photovoltaic effects

Planar double gate quantum wire transistor

S. Y. Chou and Y. Wang

Appl. Phys. Lett. 63, 788 (1993); http://dx.doi.org/10.1063/1.109908 (3 pages) | Cited 6 times

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A planar double gate quantum wire transistor (QWT) is proposed and demonstrated. The transistor uses a narrow wire gate placed inside the gap of a split gate to create a single one‐dimensional (1D) quantum wire (QW). We demonstrate theoretically and experimentally that the wire gate can create a QW potential with a better confinement and therefore larger subband separations than that in other split‐gate QWTs, and that the split gate can adjust the number of electrons inside the QW while keeping the 1D QW potential almost unchanged. Furthermore, we found that, in the double gate QWT, a 1D electron channel can spatially overlap with a 2D electron channel without significant mixing.
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85.30.Tv Field effect devices
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

Sequential‐ion‐implantation synthesis of ternary metal silicides

Zhengquan Tan, F. Namavar, S. M. Heald, and J. I. Budnick

Appl. Phys. Lett. 63, 791 (1993); http://dx.doi.org/10.1063/1.109909 (3 pages) | Cited 14 times

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By implanting two different metals in sequence into Si(100), we find that new ternary silicides can by synthesized with simple binary silicide structures. The synthesis of CoSi2‐type (Co,Fe)Si2, and CoSi‐type (Co,Fe)Si and (Fe,Ni)Si is demonstrated. The structure is largely determined by the first implanted metal and the total dose of the two metals, allowing one to design the structure of the ternary silicide. The two implanted species occupy equivalent positions in the same structure and the metal composition may be continuously varied in a given structure. This opens new possibilities for the synthesis of ternary and multinary compounds and alloys.
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61.80.Jh Ion radiation effects
61.72.uf Ge and Si
81.20.-n Methods of materials synthesis and materials processing

Systematics of electron mobility in Si/SiGe heterostructures

S. F. Nelson, K. Ismail, T. N. Jackson, J. J. Nocera, J. O. Chu, and B. S. Meyerson

Appl. Phys. Lett. 63, 794 (1993); http://dx.doi.org/10.1063/1.109910 (3 pages) | Cited 17 times

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We have investigated limits to the low temperature electron mobility in modulation‐doped Si/SiGe heterostructures grown by ultrahigh vacuum chemical vapor deposition. The temperature dependence and peak value of the mobility suggest that interface roughness is the chief scattering mechanism in samples with a thin buffer layer below the channel. Up to about 2 μm, increasing the thickness of the buffer layer raises the mobility. We have also observed a systematic increase of electron mobility with spacer (or setback) thickness, which is characteristic of remote ion scattering. The influence of background impurities is seen in the decrease of mobility with decreasing two‐dimensional gas density.  
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73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.50.Dn Low-field transport and mobility; piezoresistance
73.50.Bk General theory, scattering mechanisms

Vacancy controlled interdiffusion of the group V sublattice in strained InGaAs/InGaAsP quantum wells

W. P. Gillin, S. S. Rao, I. V. Bradley, K. P. Homewood, A. D. Smith, and A. T. R. Briggs

Appl. Phys. Lett. 63, 797 (1993); http://dx.doi.org/10.1063/1.109911 (3 pages) | Cited 17 times

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In this letter we present the results of a photoluminescence study of the interdiffusion of arsenic and phosphorous in the In0.66Ga0.33As/In0.66Ga0.33As0.7P0.3 system over the temperature range 950–600 °C. We have shown that the diffusion is Fickian with no dependence of the diffusion coefficient on the substrate doping type or etch pit density. For both tin‐ and sulfur‐doped substrates the diffusion can be described by a diffusion coefficient D, which is given by D=D0 exp(−EA/kT), where D0=23 cm2/s and EA=3.7 eV for temperatures greater than 675 °C. This activation energy is the same as that determined for the group III interdiffusion in In0.2Ga0.8As/GaAs. Below this temperature a lower activation energy process takes over with D0=5×10−10 cm2/s and EA=1.7 eV.
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66.30.Ny Chemical interdiffusion; diffusion barriers
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors

Determination of silicon point defect properties from oxidation enhanced diffusion of buried layers

Anuradha M. Agarwal and Scott T. Dunham

Appl. Phys. Lett. 63, 800 (1993); http://dx.doi.org/10.1063/1.109912 (3 pages) | Cited 5 times

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In order to characterize fundamental silicon point defect properties, the enhanced diffusion of phosphorous buried layers as a function of depth into the silicon substrate was measured during interstitial injection via thermal oxidation of the wafer surface. The measurements were used to calculate the effective interstitial diffusivity in epitaxial silicon at 1100 °C. The experimental results were also interpreted using a physical model which includes bulk recombination of interstitials with vacancies and a fast interstitial diffusivity calculated from metal gettering. The model effectively accounted for the experimental data, and through comparison of the data with model simulations, the ratio of the concentrations of vacancies and interstitials in equilibrium was obtained.
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61.72.J- Point defects and defect clusters
66.30.J- Diffusion of impurities

Anomalous photoluminescence behavior of porous Si

P. D. Stevens and R. Glosser

Appl. Phys. Lett. 63, 803 (1993); http://dx.doi.org/10.1063/1.109913 (3 pages) | Cited 18 times

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We have investigated the photoluminescence (PL) behavior of porous Si and have found that the PL intensity rises with time under exposure to continuous laser light at high power densities (≳50 W/cm2). Samples exposed to lower power density laser light exhibit the well‐known degradation of its PL intensity. As the power density is raised, the PL intensity increases with time and shows a ‘‘window’’ effect in which the PL intensities will again degrade at higher power density. Micro‐Raman studies were performed on the sample and no apparent change in crystalline structure could be found for differing power densities. We correlate this anomalous PL effect with porous Si samples etched with different HF acid concentrations and show that this effect occurs only for porous Si samples etched with a relatively high acid concentration (≳30%).
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78.55.Hx Other solid inorganic materials
78.30.Hv Other nonmetallic inorganics
81.65.-b Surface treatments

1.3 μm electroabsorption reflection modulators on GaAs

S. M. Lord, J. A. Trezza, M. C. Larson, B. Pezeshki, and J. S. Harris

Appl. Phys. Lett. 63, 806 (1993); http://dx.doi.org/10.1063/1.109914 (3 pages) | Cited 6 times

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We demonstrate a reflection electroabsorption modulator grown on a GaAs substrate operating near 1.3 μm, the dispersion minimum for silica fibers. The device was grown by molecular beam epitaxy and uses a novel technique of integrating the bottom quarter‐wave mirror into a buffer with linearly graded In composition. The active area consisted of thirty InGaAs quantum wells with GaAs barriers. The mirror was formed by layers of InGaAs and InAlAs where the In concentration was graded from 0% to 35%. A maximum relative change in reflectivity, ΔR/R, of 73% at 1.33 μm was achieved. Experimental results agree with simulations performed using the transfer matrix technique.
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42.79.Hp Optical processors, correlators, and modulators
78.66.Fd III-V semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Low‐temperature migration enhanced epitaxy of base material for AlGaAs/GaAs heterojunction bipolar transistors

Kai Zhang, Der‐Woei Wu, Jianming Fu, D. L. Miller, Mike Fukuda, Yong‐Hoon Yun, and Stephen Schauer

Appl. Phys. Lett. 63, 809 (1993); http://dx.doi.org/10.1063/1.109915 (3 pages)

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Migration enhanced epitaxy (MEE) was used in this work to grow p+‐GaAs at the substrate temperature of 300 °C for the base of AlGaAs/GaAs heterojunction bipolar transistors. The results indicated that the low‐temperature MEE‐grown p+‐GaAs epitaxial layers (p=1×1019–1×1020 cm−3) exhibited a crystalline quality comparable to those grown by standard MBE at a substrate temperature of 570 °C. AlGaAs/GaAs HBTs with low‐temperature MEE‐grown bases doped at p≊2×1019 cm−3 were fabricated by using a self‐alignment technique. For the devices with the conventional MBE‐grown base, secondary ion mass spectroscopy depth profiles showed a significant Be diffusion into the AlGaAs emitter and as a consequence, the devices showed no current gain. For the devices with the low‐temperature MBE‐grown base, there was a negligible Be penetration into the emitter and the devices exhibited a common‐emitter dc current gain of 13.
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68.55.-a Thin film structure and morphology
85.30.Pq Bipolar transistors
73.61.Ey III-V semiconductors

Observation of boron‐related photoluminescence in GaAs layers grown by molecular beam epitaxy

Steven K. Brierley, Henry T. Hendriks, William E. Hoke, Peter J. Lemonias, and David G. Weir

Appl. Phys. Lett. 63, 812 (1993); http://dx.doi.org/10.1063/1.109916 (3 pages) | Cited 6 times

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Boron‐doped GaAs films grown by molecular beam epitaxy have been studied by photoluminescence. Two boron‐related peaks have been observed in the spectra. The temperature dependence of these peaks is characteristic of acceptor levels, and a quantitative analysis yields activation energies of 71–72 and 188 meV. While the peak with the lower activation energy can be assigned with some confidence to the BAs0/− level, the second peak may be due to a BAs‐SiGa complex rather than the BAs−/−− level.
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71.55.Eq III-V semiconductors
78.55.Cr III-V semiconductors

Direct detection of atomic arsenic desorption from Si(100)

April L. Alstrin, Paul G. Strupp, and Stephen R. Leone

Appl. Phys. Lett. 63, 815 (1993); http://dx.doi.org/10.1063/1.109917 (3 pages) | Cited 5 times

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Application of the 118 nm single photon laser ionization technique to a molecular beam epitaxy machine is used for the first time to demonstrate direct desorption of As atoms from Si(100). Both As2 and As are the desorbing species from 1 ML of arsenic on silicon above 1000 K. This is in contrast to previously reported models that considered only dimer desorption. With a continuous flux of As4, the scattered and desorbing arsenic species from Si(100) are examined as a function of surface temperature (650–1200 K). Atomic desorption is large, 75%±19%, above 1000 K, and complete conversion of As4 to As2 and As occurs at 1200 K. The species selectivity of laser ionization time‐of‐flight mass spectroscopy has broader implications for GaAs growth.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces

Direct molecular‐beam epitaxial growth of ZnTe(100) and CdZnTe(100)/ZnTe(100) on Si(100) substrates

T. J. de Lyon, J. A. Roth, O. K. Wu, S. M. Johnson, and C. A. Cockrum

Appl. Phys. Lett. 63, 818 (1993); http://dx.doi.org/10.1063/1.109918 (3 pages) | Cited 13 times

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Epitaxial structures of ZnTe(100) and CdZnTe(100)/ZnTe(100) have been deposited by molecular‐beam epitaxy onto Si(100) substrates misoriented from 0° to 8° towards the [011] direction. The films were characterized with x‐ray diffraction, photoluminescence spectroscopy, optical microscopy, and stylus profilometry. Single‐crystal CdZnTe(100) films comparable in structural quality to those obtained with growth on GaAs/Si composite substrates have been demonstrated on both 4° and 8° misoriented Si with the use of ZnTe buffer layers. X‐ray rocking curves with FWHM less than 300 arcsec for ZnTe (400) and less than 160 arcsec for CdZnTe(400) have been obtained for as‐grown films. Specular surface morphologies, superior to those obtained on GaAs/Si composite substrates, are also observed.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.-a Thin film structure and morphology
85.60.Gz Photodetectors (including infrared and CCD detectors)

In surface segregation and growth‐mode transition during InGaAs growth by molecular‐beam epitaxy

H. Toyoshima, T. Niwa, J. Yamazaki, and A. Okamoto

Appl. Phys. Lett. 63, 821 (1993); http://dx.doi.org/10.1063/1.109919 (3 pages) | Cited 41 times

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An In surface segregation effect during the growth of InGaAs on GaAs by molecular‐beam epitaxy has been studied by reflection high‐energy electron diffraction measurements supported by a segregation model. Indium atoms segregate at a ratio of more than 0.8 under the conventional growth conditions for InGaAs, which causes the formation of accumulated In atoms on the surface. The transition from two‐dimensional to three‐dimensional growth occurs when the amount of In reaches around 1.7 monolayer with a nominal alloy composition greater than 0.25. This transition determines the upper limit on the In composition of the InGaAs layer for application as an electron channel in modulation‐doped field‐effect transistors.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
61.05.jh Low-energy electron diffraction (LEED) and reflection high-energy electron diffraction (RHEED)
64.75.-g Phase equilibria

Optimization of the growth parameters for the molecular‐beam epitaxial growth of strained In0.16Ga0.84As/Al0.33Ga0.67As single quantum‐well structures

M. T. Emeny, M. S. Skolnick, C. R. Whitehouse, D. G. Hayes, P. D. J. Calcott, and A. W. Higgs

Appl. Phys. Lett. 63, 824 (1993); http://dx.doi.org/10.1063/1.109920 (3 pages) | Cited 3 times

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A systematic study of the optical properties of strained InxGa1−xAs/AlyGa1−yAs (x=0.16, y=0.33) single quantum‐well structures grown by molecular‐beam epitaxy is presented. An optimized growth procedure is shown to produce quantum‐well structures exhibiting 2 K photoluminescence linewidths as low as 2.6 meV, very close to those observed for corresponding InxGa1−xAs/GaAs control structures.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors

Dislocation networks in Bi2Sr2CaCu2Oy single crystals

P. Shang, G. Yang, I. P. Jones, C. E. Gough, and J. S. Abell

Appl. Phys. Lett. 63, 827 (1993); http://dx.doi.org/10.1063/1.109921 (3 pages) | Cited 7 times

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Highly regular dislocation networks in superconducting Bi2Sr2CaCu2Oy single crystals have been observed by means of transmission electron microscopy. A model describing their geometrical configuration, Burgers vectors, and formation mechanism is presented. The ratio of the stacking fault energy to shear modulus has been estimated. Such networks are suggested as possible planar pinning centers for flux in the superconducting state.
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61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
74.25.Uv Vortex phases (includes vortex lattices, vortex liquids, and vortex glasses)
74.25.Sv Critical currents
74.72.-h Cuprate superconductors

Properties of superconductive bandpass filters with thermal switches

Y. Nagai, D. F. Hebert, T. Van Duzer, and O. Michikami

Appl. Phys. Lett. 63, 830 (1993); http://dx.doi.org/10.1063/1.109896 (3 pages) | Cited 6 times

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This letter reports experimental results on frequency tuning and switching in superconductive bandpass filters with thermal switches. The four‐pole microstrip filters with frequency of 1.5 GHz and bandwidth of 1.5% were fabricated using Nb or EuBaCuO films. The addition of thermal switches around conductors did not affect the filter characteristics. A negative frequency shift of −2 MHz was confirmed at 8 K in the Nb filter with loss of less than 0.7 dB. In contrast, a positive shift of +5 MHz was observed at 77 K in the EuBaCuO filter. Furthermore, switching with a large difference of approximately 50 dB in loss was achieved in the Nb filters.
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85.25.Qc Superconducting surface acoustic wave devices and other superconducting devices
84.30.Vn Filters

Improvements of microstructural and superconducting properties of Ag‐Bi2Sr2CaCu2Ox screen‐printed tape by controlled oxygen partial pressure during cooling procedure

H. Noji, W. Zhou, B. A. Glowacki, and A. Oota

Appl. Phys. Lett. 63, 833 (1993); http://dx.doi.org/10.1063/1.109897 (3 pages) | Cited 6 times

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The effect of different cooling procedures, after sintering, on the microstructural and superconducting properties of Bi2Sr2CaCu2Ox (B‐2212) screen‐printed tapes has been investigated. It was found that the amorphous phase originally present in grain boundaries at the sintering temperature undergoes a conversion to the Bi‐2212 phase during slow cooling. However, the excess oxygen absorbed during slow cooling (in 21% oxygen) disturbs the order and ordering process of Bi‐2212 crystals, but if the slow cooling process is conducted under monotonically reduced oxygen partial pressure, to ensure that the optimum oxidation state at sintering temperature of the Bi‐2212 phase can be retained during the cooling procedure, tapes are then characterized by narrow grain boundaries and the highest Jc value ≳104 A/cm2 at 77 K and 0 T.
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84.71.Mn Superconducting wires, fibers, and tapes
74.25.Sv Critical currents
74.72.-h Cuprate superconductors
81.20.Ev Powder processing: powder metallurgy, compaction, sintering, mechanical alloying, and granulation

Processing dependence of the interfacial microstructure of Ag contacts to YBa2Cu3O7−δ thin films

Z. H. Gong, F. Vassenden, R. Fagerberg, J. K. Grepstad, A. Bardal, and R. Høier

Appl. Phys. Lett. 63, 836 (1993); http://dx.doi.org/10.1063/1.109870 (3 pages) | Cited 7 times

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The interfacial microstructure of three differently prepared silver contacts on c‐axis oriented YBa2Cu3O7−δ (YBCO) thin films was examined using high‐resolution transmission electron microscopy (HRTEM). For contacts prepared in situ by Ag sputter deposition on films maintained at elevated temperature and ex situ by Ag vapor deposition on films annealed in ultrahigh vacuum prior to metallization, regions of atomically sharp YBCO(001)/Ag interfaces were observed. In contrast, the cross‐section HRTEM images of contacts prepared by in situ Ag deposition at room temperature reveal an amorphous interfacial zone, typically 20 Å thick. Scattered Y2O3 precipitates are found at the YBCO surface of all three contacts. The data suggest that intrinsic reactions between Ag and YBCO(001) are negligible, and that the amorphous interface layer for in situ contacts to cold films must be ascribed to reactions with gaseous impurities in the sputter chamber ambient. In conclusion, we strongly emphasize the importance of using ultrahigh purity process gases in order to avoid formation of a resistive interfacial barrier.
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68.55.-a Thin film structure and morphology
74.78.Fk Multilayers, superlattices, heterostructures
74.78.-w Superconducting films and low-dimensional structures
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces

Epitaxial τMnAl/NiAl magnetic multilayers on AlAs/GaAs

M. Tanaka, J. P. Harbison, T. Sands, T. L. Cheeks, J. De Boeck, D. M. Hwang, L. T. Florez, and V. G. Keramidas

Appl. Phys. Lett. 63, 839 (1993); http://dx.doi.org/10.1063/1.109871 (3 pages) | Cited 6 times

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We have successfully grown a novel type of epitaxial metallic multilayers consisting of ultrathin ferromagnetic tetragonal τMnAl and nonmagnetic (CsCl‐type) NiAl on (001) GaAs substrates using molecular beam epitaxy. Reflection high energy electron diffraction and cross‐sectional transmission electron microscopy (TEM) show that monocrystalline MnAl/NiAl multilayers are formed with the expected epitaxial orientations and that the c axis of the tetragonal structure of the ultrathin MnAl film is aligned perpendicular to the substrate. Composition modulation is clearly evidenced by TEM even when the thickness of each MnAl and NiAl layer is as thin as 3 monolayers. Perpendicular magnetization of the MnAl/NiAl multilayers is shown by both magnetization and magnetotransport measurements at room temperature, exhibiting remarkably square hysteresis loops, high values (Mr≳300 emu/cm3) of remanent magnetization, and relatively low values of coercive field (0.2<Hc<1 kOe).
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75.70.-i Magnetic properties of thin films, surfaces, and interfaces
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties

Enhanced differential magnetostrictive response in annealed Terfenol‐D

N. Galloway, M. P. Schulze, R. D. Greenough, and D. C. Jiles

Appl. Phys. Lett. 63, 842 (1993); http://dx.doi.org/10.1063/1.110776 (3 pages) | Cited 5 times

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The field and pressure dependencies of the magnetostriction of Tb0.316Dy0.684Fe1.982 have been measured in a grain‐oriented rod after thermally annealing for 1 day at 850 °C and for 4 days at 950 °C in an argon atmosphere. The results of the heat treatment are a fivefold increase in the strain coefficient d33(=dλ/dH) and a 100% increase in the maximum strain (λ). There was also an increase in the λ‐vs‐H hysteresis. Under compressive uniaxial stress there was virtually no bulk change in magnetostrictive strain until the field exceeded a critical value which depended on the applied stress, for instance ∼12 kA/m under a stress of 6 MPa.
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75.80.+q Magnetomechanical effects, magnetostriction
81.40.Rs Electrical and magnetic properties related to treatment conditions
75.50.Bb Fe and its alloys

Secondary‐neutral microprobe with electron‐gas post‐ionization

W. Bieck, H. Gnaser, and H. Oechsner

Appl. Phys. Lett. 63, 845 (1993); http://dx.doi.org/10.1063/1.109872 (3 pages) | Cited 3 times

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The essential features and the performance data of a recently developed secondary‐neutral microprobe are described which interfaces the well‐established technique of electron gas (plasma) post‐ionization with a high‐transmission magnetic sector mass spectrometer. Small‐area analysis is accomplished by means of a separate high‐brightness liquid‐metal (Ga+) ion source. For 20 keV Ga+ ions and 1 nA beam current the intensities of post‐ionized sputtered neutrals amount to some 103 counts/s for pure elements, and secondary neutral micrographs can be acquired with an image resolution in the μm range. Due to the high transmission of the mass spectrometer secondary‐neutral intensities up to 109 counts/s per 1 mA primary current can be obtained in the direct bombardment mode (i.e., by extracting the sputtering beam out of the plasma), thus extending the detection limit down to the 10 ppb regime. Furthermore, the instrument can be operated at high mass resolution (M/ΔM=9500) providing the option of isotope analysis by means of secondary‐neutral mass spectrometry.
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07.75.+h Mass spectrometers
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
07.78.+s Electron, positron, and ion microscopes; electron diffractometers
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
FREE

Comment on ‘‘35% efficient nonconcentrating novel silicon solar cell’’

Antonio Luque

Appl. Phys. Lett. 63, 848 (1993); http://dx.doi.org/10.1063/1.109873 (1 page) | Cited 10 times

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Abstract Unavailable
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84.60.Jt Photoelectric conversion
85.30.De Semiconductor-device characterization, design, and modeling
72.40.+w Photoconduction and photovoltaic effects
FREE

Comment on ‘‘35% efficient nonconcentrating novel silicon solar cell’’

E. Demesmaeker, M. Ghannam, J. Nijs, R. Mertens, R. Van Overstraeten, H. A. Aulich, R. Wieting, M. Rodot, and J. C. Müller

Appl. Phys. Lett. 63, 849 (1993); http://dx.doi.org/10.1063/1.109874 (1 page) | Cited 6 times

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Abstract Unavailable
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84.60.Jt Photoelectric conversion
85.30.De Semiconductor-device characterization, design, and modeling
72.40.+w Photoconduction and photovoltaic effects
FREE

Comment on ‘‘35% efficient nonconcentrating novel silicon solar cell’’

Arturo Morales‐Acevedo

Appl. Phys. Lett. 63, 850 (1993); http://dx.doi.org/10.1063/1.109875 (1 page) | Cited 6 times

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Abstract Unavailable
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84.60.Jt Photoelectric conversion
85.30.De Semiconductor-device characterization, design, and modeling
72.40.+w Photoconduction and photovoltaic effects
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