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20 Nov 1995

Volume 67, Issue 21, pp. 3057-3211

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Self‐restoration of p‐n junctions in (Hg,Cd)Te

Igor Lyubomirsky, Vera Lyakhovitskaya, Robert Triboulet, and David Cahen

Appl. Phys. Lett. 67, 3132 (1995); http://dx.doi.org/10.1063/1.114857 (3 pages) | Cited 4 times

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While a p‐n junction is a stable situation for electronic carriers, it represents an unstable one for the very dopants that create the junction, i.e., the junction is only kinetically stabilized against equilibration of the dopant concentrations in the chemical and electrical potential gradients in the junction region. However, when a dopant migrates with a charge opposite to the effective one that it has as a dopant, the electrical potential gradient, instead of destabilizing, can now help to stabilize the junction. Ag, which acts as an acceptor in (Hg,Cd)Te, is an example of such a dopant. We show here that in Cd‐rich n‐(Hg,Cd)Te, Ag creates a p‐n junction that is capable of restoring itself after being smeared out by small perturbations. This behavior is inconsistent with pure kinetic stabilization of the junction and indicates that Ag dissolution in (Hg,Cd)Te strongly deviates from ideal behavior. Reasons for this nonideality are suggested. © 1995 American Institute of Physics.
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61.72.uj III-V and II-VI semiconductors
66.30.J- Diffusion of impurities

Fast metal diffusers in Si in the presence of Si self‐interstitial traps

H.‐J. Gossmann, P. A. Stolk, D. J. Eaglesham, C. S. Rafferty, and J. M. Poate

Appl. Phys. Lett. 67, 3135 (1995); http://dx.doi.org/10.1063/1.114858 (3 pages) | Cited 2 times

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The diffusion of Au, Pt, and Zn in Si yield Si self‐interstitial diffusivities, DI, that exceed those obtained from dopant marker experiments by 6 orders of magnitude at 800 °C. Both types of experiments can be reconciled by assuming the existence of a nonannihilating interstitial trap, related to carbon. In this context, selected metal diffusion data are reanalyzed. Nonannihilating immobile traps and a second‐order reaction involving interstitial carbon and carbon–carbon pairs are considered. Quantitative point‐defect parameters are extracted at 1115 °C for an assumed trap concentration of Ctt=5×1016 cm−3. In all cases and independent of the value of Ctt, excellent fits to concentration versus depth profiles of Zn are obtained; the extracted equilibrium concentration of Si self‐interstitials, CI∗, varies inversely with Ctt, while DICI∗ remains approximately constant. Hence agreement, or disagreement, of metal diffusion results with the Si self‐diffusion coefficient cannot be used to exclude or prove trap‐limited diffusion. Literature values of point‐defect parameters obtained by neglecting traps represent lower bounds on DI and upper bounds on CI∗. The time evolution of the Zn profile in the presence of traps is discussed. Proper inclusion of traps in the analysis of metal diffusion data leads to a decrease in the extracted activation energy of DI. © 1995 American Institute of Physics.
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61.72.J- Point defects and defect clusters
61.72.uf Ge and Si
66.30.H- Self-diffusion and ionic conduction in nonmetals
66.30.J- Diffusion of impurities

(111)A CdTe rotation growth on (111) Si with low growth rate by metalorganic chemical vapor deposition

H. Ebe and Y. Nishijima

Appl. Phys. Lett. 67, 3138 (1995); http://dx.doi.org/10.1063/1.114859 (3 pages) | Cited 9 times

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(111)A CdTe epilayers have been grown directly on (111) silicon substrates with the low growth rate of less than 0.5 μm/h by metalorganic chemical vapor deposition (MOCVD). The full width at half maximum (FWHM) of the x‐ray rocking curve of a 1 μm thick epilayer is 100 arcsec, which is much better than the value for (111)B CdTe/(100)Si. The low growth rate effects are deduced from the classical capillarity theory. The nucleation stages were examined by atomic force microscopy (AFM), which showed that the nuclei were less in number when growing with the low growth rate. The geometrical advantages of (111)A CdTe/(111) Si for annihilating the dislocations are also discussed. © 1995 American Institute of Physics.
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68.55.-a Thin film structure and morphology
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Surface dimerization induced CuPtB versus CuPtA ordering of GaInP alloys

S. B. Zhang, Sverre Froyen, and Alex Zunger

Appl. Phys. Lett. 67, 3141 (1995); http://dx.doi.org/10.1063/1.114860 (3 pages) | Cited 62 times

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Using a valence force field approach and ab initio pseudopotential calculations, we examine the role of subsurface strain in the ordering of Ga0.5In0.5P alloys. We show that depending on the orientation of the surface phosphorus dimers, these alloys can have (i) a CuPtA ordering for 1×2 or c(4×4) reconstruction; (ii) a CuPtB ordering for 2×1 or β2(2×4) reconstruction; and (iii) a triple period ordering for 2×3 or c(8×6) reconstruction. These results are in good agreement with recent experiments of Gomyo et al. [Phys. Rev. Lett. 72, 673 (1994); Jpn. J. Appl. Phys. 34, L469 (1995)]. © 1995 American Institute of Physics.
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68.35.B- Structure of clean surfaces (and surface reconstruction)

Nanometer‐scale field‐induced oxidation of Si(111):H by a conducting‐probe scanning force microscope: Doping dependence and kinetics

T. Teuschler, K. Mahr, S. Miyazaki, M. Hundhausen, and L. Ley

Appl. Phys. Lett. 67, 3144 (1995); http://dx.doi.org/10.1063/1.114861 (3 pages) | Cited 71 times

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Hydrogen‐terminated Si(111) was patterned on the nanometer scale by field‐induced oxidation using a biased conducting‐probe scanning force microscope. The kinetics of oxide growth as well as its dependence on doping are investigated. Field‐induced oxidation is observed for voltages exceeding a doping dependent threshold above which oxidation kinetics follows a power law. © 1995 American Institute of Physics.
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68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)
68.37.Ps Atomic force microscopy (AFM)
68.37.Rt Magnetic force microscopy (MFM)
68.37.Uv Near-field scanning microscopy and spectroscopy
81.65.-b Surface treatments
81.07.-b Nanoscale materials and structures: fabrication and characterization
81.16.-c Methods of micro- and nanofabrication and processing
85.35.-p Nanoelectronic devices

Contact and distributed effects in quantum well infrared photodetectors

M. Ershov, V. Ryzhii, and C. Hamaguchi

Appl. Phys. Lett. 67, 3147 (1995); http://dx.doi.org/10.1063/1.114862 (3 pages) | Cited 50 times

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We propose a simple distributed model for intersubband quantum well infrared photodetectors (QWIPs), which explicitly takes into account the injecting properties of the contacts. We show that the QWIP operation with multiple QWs involves the formation of a high‐field domain near the emitter, caused by the modulation of the bound electron density in the QWs by applied voltage and infrared radiation. The external characteristics of the QWIP (total current, differential resistance, and quasistatic capacitance) are strong functions of the voltage and radiation intensity. © 1995 American Institute of Physics.
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73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
78.66.-w Optical properties of specific thin films
85.60.Gz Photodetectors (including infrared and CCD detectors)

Mott ionization of excitons in n‐type Zn1−xMnxSe epilayers

G. A. Balchin, L. M. Smith, H. Abad, and B. T. Jonker

Appl. Phys. Lett. 67, 3150 (1995); http://dx.doi.org/10.1063/1.115145 (3 pages)

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Recently, the first controlled n‐type doping of Zn1−xMnxSe epilayers was reported. Using time‐resolved photoluminescence we show that exciton ionization in the moderately doped samples occurs at a significantly lower temperature (50 K) than in undoped material (180 K). This behavior is consistent with Mott ionization of excitons from the increased majority carrier density at higher temperatures. The density and temperature at which the ionization occurs are estimated using calculations of the Mott density and the density‐dependent exciton binding energy. No excitons are observed down to 2 K in the samples, which were doped at the highest densities, suggesting that these samples were degenerately doped. © 1995 American Institute of Physics.
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61.72.uj III-V and II-VI semiconductors
71.35.-y Excitons and related phenomena
78.55.Et II-VI semiconductors
78.66.Hf II-VI semiconductors

Auger lifetime in InAs, InAsSb, and InAsSb‐InAlAsSb quantum wells

J. R. Lindle, J. R. Meyer, C. A. Hoffman, F. J. Bartoli, G. W. Turner, and H. K. Choi

Appl. Phys. Lett. 67, 3153 (1995); http://dx.doi.org/10.1063/1.115146 (3 pages) | Cited 27 times

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The intensity‐dependent photoconductive response to 2.06 μm excitation has been used to determine Shockley‐Read and Auger lifetimes for InAs, InAs0.91Sb0.09, and an InAs0.85Sb0.15‐InAlAsSb multiple quantum well. The Auger rate at 77 K correlates with the proximity to resonance between the energy gap and the split‐off gap. Thus the Auger coefficient in the alloy decreases with decreasing temperature, whereas that in the quantum well increases by nearly a factor of 5 between 300 and 77 K. © 1995 American Institute of Physics.
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73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
73.50.Pz Photoconduction and photovoltaic effects
73.61.Ey III-V semiconductors

Dopant interactions during the diffusion of arsenic and boron in opposite directions in polycrystalline/monocrystalline silicon structures

Joachim N. Burghartz, Carol L. Stanis, and Paul A. Ronsheim

Appl. Phys. Lett. 67, 3156 (1995); http://dx.doi.org/10.1063/1.115147 (3 pages)

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Experimental results of the effects of the arsenic doping concentration on the boron outdiffusion in n‐polycrystalline/p‐monocrystalline silicon structures are presented. The boron diffusivity is only 30 times larger in polycrystalline silicon than in monocrystalline silicon if the arsenic doping is high enough to cause enhanced grain growth. The diffusivity increase is about 130 if the polycrystalline silicon has small grains due to low arsenic doping. The boron loss from the base region of an advanced bipolar transistor doping profile by outdiffusion into the emitter polycrystalline silicon is of the order of 20% and needs to be considered for accurate device modeling. © 1995 American Institute of Physics.
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61.72.uf Ge and Si
66.30.J- Diffusion of impurities

Space‐charge‐limited injection in n+‐i‐n+ structures fabricated by a focused ion beam

S. W. Hwang, H. J. Lezec, T. Sakamoto, N. Nakamura, and J. H. Pak

Appl. Phys. Lett. 67, 3159 (1995); http://dx.doi.org/10.1063/1.115148 (3 pages)

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Transport characteristics of n+‐i‐n+ structures fabricated on a GaAs/AlGaAs HEMT wafer are presented. An insulating strip (i) between two‐dimensional electron gases (n+) is created by a single line scan of a focused ion beam. At sufficiently large biases, the current–voltage (I–V) characteristics of the n+‐i‐n+ structures display highly linear increases of the currents as a function of the biases. The observed I–V’s are quantitatively explained by the space‐charge‐limited injection into the insulating region when the bias is large enough for the flatband condition. The charged defect density and the length of the insulating region are obtained from the I–V characteristics. © 1995 American Institute of Physics.
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73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

Production of atomic hydrogen in Al–SiO2–Si systems by vacuum ultraviolet radiation

K. G. Druijf, J. M. M. de Nijs, E. van der Drift, E. H. A. Granneman, and P. Balk

Appl. Phys. Lett. 67, 3162 (1995); http://dx.doi.org/10.1063/1.115149 (3 pages)

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A study of the generation of H‐induced defects in the Al–SiO2–Si system by vacuum ultraviolet radiation (hν=10 eV) shows that small cross‐section hole traps in the bulk of the oxide and donor‐type states at the Si–SiO2 interface are formed by different reactions paths. In both cases the production of atomic H, required for obtaining these defects, only involves neutral species. However, the source of the hydrogen producing the bulk hole traps is located at the Al–SiO2 interface, the source for the hydrogen inducing the donor‐type interface states at the Si–SiO2 interface. © 1995 American Institute of Physics.
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61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
73.20.Hb Impurity and defect levels; energy states of adsorbed species
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)

Plasmons in a superlattice in a parabolic quantum well

M. Sundaram, S. J. Allen, M. R. Geller, K. L. Campman, and A. C. Gossard

Appl. Phys. Lett. 67, 3165 (1995); http://dx.doi.org/10.1063/1.115150 (3 pages) | Cited 1 time

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Well‐defined plasma oscillations are observed in a superlattice miniband even though the Fermi energy lies in the minigap. Despite the complex band structure, the resonance shows a remarkable insensitivity to changes in the number of electrons in the parabolic well in which the superlattice is placed, a feature of the generalized Kohn theorem that is expected only in the limit that the Fermi energy is near the bottom of the lowest miniband. © 1995 American Institute of Physics.
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73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
78.66.Fd III-V semiconductors

Edge‐emitting quantum well heterostructure laser diodes with auxiliary native‐oxide vertical cavity confinement

P. W. Evans, N. Holonyak, S. A. Maranowski, M. J. Ries, and E. I. Chen

Appl. Phys. Lett. 67, 3168 (1995); http://dx.doi.org/10.1063/1.115151 (3 pages) | Cited 8 times

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Data are presented demonstrating edge‐emitting laser diode operation of AlyGa1−yAs– GaAs–InxGa1−xAs quantum well heterostructures modified by the formation of a buried native‐oxide distributed Bragg reflecting (DBR) mirror adding vertical confinement to the longitudinal laser cavity. The bottom DBR mirror, combined with the highly reflective top p‐contact metallization (Ag), forms a thin broadband vertical cavity. The auxiliary vertical mirrors are tuned to improve the coupling of the spontaneous emission to the longitudinal lasing mode, resulting in reduced threshold currents and modified emission characteristics below threshold. © 1995 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.-v Laser optical systems: design and operation

Direct measurement of the internal electric field distribution in a multilayer organic light‐emitting diode

I. H. Campbell, M. D. Joswick, and I. D. Parker

Appl. Phys. Lett. 67, 3171 (1995); http://dx.doi.org/10.1063/1.115152 (3 pages) | Cited 46 times

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We present a general electroabsorption technique to measure the electric field in each layer of multilayer organic light‐emitting diodes. The electroabsorption signal from each layer is identified spectroscopically and measured as a function of dc bias. Measurements were made on three layer devices consisting of a hole transport layer, a light‐emitting layer, and an electron transport layer. In reverse bias, without significant charge injection, the dc electric field is uniform throughout the device. In forward bias, the dc electric field is distributed nonuniformly; it is smallest in the light‐emitting layer and largest in the hole transport layer. The nonuniform dc electric field distribution is caused by the accumulation of electrons (holes) at the interface between the light‐emitting layer and the hole (electron) transport layer. The maximum accumulated charge densities are 2×1012 electrons/cm2 and 3×1011 holes/cm2. These results highlight the carrier blocking role of monopolar transport layers and demonstrate a powerful technique to characterize multilayer organic structures. © 1995 American Institute of Physics.
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73.61.Ph Polymers; organic compounds
78.66.Qn Polymers; organic compounds
85.60.Jb Light-emitting devices

Single‐gate multichannel amorphous silicon thin‐film transistors

Yue Kuo

Appl. Phys. Lett. 67, 3174 (1995); http://dx.doi.org/10.1063/1.115153 (3 pages)

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A redundant thin‐film transistor (TFT), which has multiple sub‐TFTs sharing one gate, is presented and studied. This transistor can be fabricated with two photomasks. It has transfer characteristics similar to those of a conventional single‐channel TFT, except for (1) the negative‐direction shift of the curve in the low drain current range, (2) the two‐stage turn‐on mechanism in the high drain current range, and (3) the high photoleakage current at the high drain voltage. The first phenomenon is due to the inclusion of electron accumulation interfaces in the semiconductor layer. The second phenomenon is caused by the sequential turn‐on of various sub‐TFTs at various gate voltages. The last phenomenon can be explained by the photoresistor characteristics of the top a‐Si:H layer. © 1995 American Institute of Physics.
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73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
85.30.Tv Field effect devices

YBa2Cu3O7 step‐edge dc SQUID with coplanar control lines

H. Hasegawa, Y. Tarutani, T. Fukazawa, U. Kabasawa, and K. Takagi

Appl. Phys. Lett. 67, 3177 (1995); http://dx.doi.org/10.1063/1.115154 (3 pages) | Cited 5 times

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A dc superconducting quantum interference device (SQUID) with coplanar control lines has been fabricated from a single layer of YBa2Cu3O7 thin film. Step‐edge junctions were formed using resist/Si double‐mask layers. Current–voltage characteristics of this SQUID at 77 K show Shapiro steps under microwave irradiation and are qualitatively consistent with the resistively shunted junction (RSJ) model. The spacing between the closed loop and the coplanar control lines in the tested SQUIDs ranged from 0.2 to 1.5 μm. The measured output voltage‐control current characteristics showed that the experimentally derived mutual inductances were a function of the spacing, in agreement with the calculated results. The typical mutual inductance for a spacing of 1.0 μm was ∼0.5 pH, which is adequate for detecting signals of flux‐transfer logic gates in which the typical logic amplitude is ∼0.1 mA. A coplanar structure is thus useful for logic gate applications. © 1995 American Institute of Physics.
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74.78.-w Superconducting films and low-dimensional structures
85.25.Dq Superconducting quantum interference devices (SQUIDs)

Alternating‐current losses in silver‐sheathed (Bi,Pb)2Sr2Ca2Cu3O10 tapes II: Role of interfilamentary coupling

Y. Fukumoto, H. J. Wiesmann, M. Garber, M. Suenaga, and P. Haldar

Appl. Phys. Lett. 67, 3180 (1995); http://dx.doi.org/10.1063/1.115155 (3 pages) | Cited 14 times

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ac losses at 60 Hz have been measured for silver‐sheathed (Bi,Pb)2Sr2Ca2Cu3O10 multifilamentary tapes at 27 and 77 K to investigate the role of interfilamentary coupling. The results are qualitatively well described by the use of the concept of the critical coupling length lc. Further, it is shown that to obtain effective reduction of the coupling loss, a very small twist pitch length (≪1 cm) as well as a substantial reduction in the filament thickness are required for an applied ac field of, for example, 100 rms A/cm at 77 K. © 1995 American Institute of Physics. [S0003‐6951(95)02147‐5]
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84.71.Mn Superconducting wires, fibers, and tapes

Operation of high‐temperature rf SQUID magnetometers using dielectric SrTiO3 resonators

Y. Zhang, M. Gottschlich, H. Soltner, E. Sodtke, J. Schubert, W. Zander, and A. I. Braginski

Appl. Phys. Lett. 67, 3183 (1995); http://dx.doi.org/10.1063/1.115156 (3 pages) | Cited 4 times

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The operation of YBa2Cu3O7 rf superconducting quantum interference devices (SQUIDs) using a dielectric SrTiO3 resonator as tank circuit was tested. At 77 K, we attained for such resonators unloaded quality factors Q0 up to 7000 at resonant frequencies near 1 GHz, when measuring without electromagnetic shielding. For a washer SQUID with an area of 4×4 mm2 and an inductance of ≂100 pH, which was properly coupled to the resonator, we measured an approximately 60 μV peak‐to‐peak SQUID signal and a white flux noise spectral density of SΦ1/2=1×10−5Φ0/√Hz, corresponding to a field sensitivity of BN=105 fT/√Hz. With an additional single‐layer flux transformer with a diameter of the pickup loop of 22 mm in flip‐chip arrangement, the field sensitivity was improved to 30 fT/√Hz. © 1995 American Institute of Physics.
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07.55.Ge Magnetometers for magnetic field measurements
85.25.Dq Superconducting quantum interference devices (SQUIDs)

Critical currents and pinning forces in a‐axis oriented EuBa2Cu3O7/PrBa2Cu3O7 superlattices

M. Vélez, J. I. Martín, and J. L. Vicent

Appl. Phys. Lett. 67, 3186 (1995); http://dx.doi.org/10.1063/1.115157 (3 pages) | Cited 6 times

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a‐axis oriented EuBa2Cu3O7/PrBa2Cu3O7 (EBCO/PBCO) superlattices have been grown by dc sputtering. The critical current (JC) behavior is modified by the pinning force arising from the insulating PrBa2Cu3O7 layers, which in a‐axis oriented superlattices are perpendicular to the Cu–O planes. Depending on the EBCO and PBCO layer thicknesses the pinning forces deviate from the usual scaling laws as a function of temperature observed in single films. When B is perpendicular to the sample, an exponential dependence of JC(B) appears as the PBCO thickness is increased (coupling is reduced), and also as the thickness of the EBCO layer is reduced. © 1995 American Institute of Physics.
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74.25.Uv Vortex phases (includes vortex lattices, vortex liquids, and vortex glasses)
74.78.-w Superconducting films and low-dimensional structures
74.78.Fk Multilayers, superlattices, heterostructures

Measurement of the ac power loss of (Bi,Pb)2Sr2Ca2Cu3Ox composite tapes using the transport technique

S. Fleshler, L. T. Cronis, G. E. Conway, A. P. Malozemoff, T. Pe, J. McDonald, J. R. Clem, G. Vellego, and P. Metra

Appl. Phys. Lett. 67, 3189 (1995); http://dx.doi.org/10.1063/1.115158 (3 pages) | Cited 32 times

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The transport self‐field ac loss voltages of (Bi,Pb)2Sr2Ca2Cu3Ox (Bi‐2223) multifilamentary tapes depend strongly on the voltage lead configuration. We have measured the loss voltage as a function of the measuring circuit loop size defined by the voltage leads and the tapes for well‐defined lead geometries. The loss signal was found to reach a limiting value when the length of the loop transverse to the tape was several times the tape width. This limiting voltage represents the ‘‘true’’ self‐field ac loss as predicted by new theoretical analysis. © 1995 American Institute of Physics.
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84.71.Mn Superconducting wires, fibers, and tapes

Simple computer aided design formula and network interpretation for loss evaluation in microstrip superconductor–conductor bilayer structure

D. Ladret, C. Migliaccio, B. Cabon, and J. Chilo

Appl. Phys. Lett. 67, 3192 (1995); http://dx.doi.org/10.1063/1.115159 (2 pages)

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Line resistance analytical results obtained from the proposed simple surface impedance formula describing a superconductor–conductor bilayer structure were found in good agreement with numerical results. Network interpretation of this structure is performed. Important information about the loss frequency behavior (frequency cutoff, asymptotic variation) and influence of the thickness ratio of the two layers on bilayer losses, are commented on. © 1995 American Institute of Physics.
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74.78.Fk Multilayers, superlattices, heterostructures
85.25.-j Superconducting devices

Fabrication of NiFe thin film elements by dry etching using CH4/H2/O2

B. Khamsehpour, C. D. W. Wilkinson, and J. N. Chapman

Appl. Phys. Lett. 67, 3194 (1995); http://dx.doi.org/10.1063/1.115160 (3 pages) | Cited 12 times

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A mixture of methane, hydrogen, and oxygen has been used to etch thin films of NiFe. The variation of etch rate with concentration of methane and oxygen has been investigated. By using a SrF2 mask, patterned by liftoff, small micrometer‐sized elements have been fabricated. It is demonstrated that the use of CH4/H2/O2 as an etchant yields elements possessing similar micromagnetic properties to those produced by conventional liftoff. The process has also been successfully employed to etch other important magnetic thin films. © 1995 American Institute of Physics.
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81.65.-b Surface treatments
85.40.Hp Lithography, masks and pattern transfer

Magnetic properties of rapidly quenched high remanence Zr added Sm–Fe–N isotropic powders

T. Yoneyama, T. Yamamoto, and T. Hidaka

Appl. Phys. Lett. 67, 3197 (1995); http://dx.doi.org/10.1063/1.115161 (3 pages) | Cited 22 times

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The magnetic properties and microstructures of rapidly quenched Sm–Fe–N powders with low Sm contents and Zr and Co addition have been studied. High remanence values of 9.4 kG with high HcJ values of 7–10 kOe were obtained for isotropic powders. The x‐ray diffraction analysis and transmission electron microscopy (TEM) observation showed these alloy powders to consist of a nanoscale mixture with a SmFe7Nx phase with the TbCu7‐type structure and α‐Fe in the size range of 20–30 nm. It is presumed that the high remanence is due to the small crystal size and exchange coupling at interphase boundaries. © 1995 American Institute of Physics.  
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75.50.Bb Fe and its alloys
75.50.Tt Fine-particle systems; nanocrystalline materials

Field emission switch

Gary M. McClelland and Fumiya Watanabe

Appl. Phys. Lett. 67, 3200 (1995); http://dx.doi.org/10.1063/1.115162 (3 pages)

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Large positive and negative voltage pulses applied to field emission tips can rearrange atomic or molecular adsorbates on the tip. If this rearrangement persists when field emission is measured at a lower negative voltage, the rearrangement will alter the field emission rate, and the device will function as a switch with memory. This effect has been observed for single sodium atoms adsorbed on a tungsten tip and is applicable to adsorbed films or ferroelectric layers. © 1995 American Institute of Physics.
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68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)
68.37.Ps Atomic force microscopy (AFM)
68.37.Rt Magnetic force microscopy (MFM)
68.37.Uv Near-field scanning microscopy and spectroscopy
79.70.+q Field emission, ionization, evaporation, and desorption

Reversible hydrogen annealing of metal‐oxide‐silicon carbide devices at high temperatures

Amir Baranzahi, Anita Lloyd Spetz, and Ingemar Lundström

Appl. Phys. Lett. 67, 3203 (1995); http://dx.doi.org/10.1063/1.115163 (3 pages) | Cited 26 times

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We report on a reversible hydrogen annealing effect observed in platinum–silicon dioxide–silicon carbide structures at temperatures above about 650 °C. It appears as a decrease of the inversion capacitance in the presence of hydrogen. This phenomenon is shown to depend on hydrogen atoms, created on the catalytic metal, that pass through the oxide and interact with charge generation sites at the oxide–silicon carbide interface. The consequence of the observation for chemical sensors based on silicon carbide is discussed. The results are phenomenological, since no details of the annealing chemistry could be developed from the present experiments. We find, however, that the annealing process and its reversal have activation energies of about 0.9 eV and 2.9 eV/site, respectively. © 1995 American Institute of Physics.
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61.72.uf Ge and Si
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
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