APL Nameplate
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

15 Mar 1993

Volume 62, Issue 11, pp. 1173-1303

Page 2 of 2 Pages Previous Page | Jump to Page

Effect of post‐growth cooling ambient on acceptor passivation in carbon‐doped GaAs grown by metalorganic chemical vapor deposition

S. A. Stockman, A. W. Hanson, S. L. Jackson, J. E. Baker, and G. E. Stillman

Appl. Phys. Lett. 62, 1248 (1993); http://dx.doi.org/10.1063/1.108748 (3 pages) | Cited 14 times

Full Text: | Download PDF

Show Abstract
The degree of unintentional hydrogen passivation of acceptors in heavily C‐doped GaAs (p≳1018 cm−3) grown by metalorganic chemical vapor deposition has been found to be a strong function of post‐growth cool‐down ambient. The carbon concentration in the GaAs and the amount of AsH3 in the cool‐down ambient are the most important factors affecting passivation. Carbon acceptors can be reactivated by annealing in N2, then repassivated by heating and re‐cooling in an AsH3/H2 or PH3/H2 ambient. Secondary ion mass spectrometry analysis shows that the hydrogen concentration is significantly higher in a C‐doped GaAs surface layer which is exposed to the cool‐down ambient than in a layer which is buried beneath n‐type GaAs. This result is consistent with observations in n‐p‐n heterojunction bipolar transistor structures, where the fraction of C acceptors passivated in the base region is found to be less than in a single layer grown under identical conditions. Be‐doped GaAs grown by gas‐source molecular beam epitaxy has also been heated and cooled in AsH3‐containing ambients, but no acceptor passivation is detectable by Hall effect measurements.
Show PACS
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
61.72.uj III-V and II-VI semiconductors
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
73.61.Ey III-V semiconductors

Electrical switching in methyltriphenylarsonium‐(TCNQ)2 under pressure

T. Ravindran and S. V. Subramanyam

Appl. Phys. Lett. 62, 1251 (1993); http://dx.doi.org/10.1063/1.108749 (2 pages)

Full Text: | Download PDF

Show Abstract
Electrical switching has been observed in methyltriphenylarsonium‐(TCNQ)2 (7,7,8,8‐tetracyanoquinodimethane) at different pressures up to 8 GPa at a temperature of 300 K. At high fields ∼3×103 V/cm, the sample switches from an off state of several kΩ resistance to low resistance on state of several ohms. Pulsed current‐voltage characteristics reveal heating contribution to nonohmic conduction and switching. The switching time recorded is 0.5 ms. Nonohmic conduction is discussed in terms of space charge limited currents possibly leading to a structural phase transition.
Show PACS
72.20.Ht High-field and nonlinear effects
72.60.+g Mixed conductivity and conductivity transitions
72.80.-r Conductivity of specific materials

Calibration of the multiple quantum well probe technique for dry‐etch‐induced damage analysis

D. L. Green, J. A. Skidmore, D. G. Lishan, E. L. Hu, and P. M. Petroff

Appl. Phys. Lett. 62, 1253 (1993); http://dx.doi.org/10.1063/1.108750 (3 pages) | Cited 3 times

Full Text: | Download PDF

Show Abstract
The multiple quantum well (MQW) probe technique has provided information of the depth distribution of dry‐etch‐induced damage. The observed changes in the quantum well cathodoluminescence intensities or peak positions have been uniquely attributed to the dry etching process. There are indications, however, that this premise may not be justified for some applications. Two studies are described, which we have carried out to establish critical calibrations of the MQW probe technique. A slow, carefully controlled wet etch of the starting MQW probe structure allowed us to observe a reduction in luminescence intensity of quantum wells located less than 20 nm from the surface. The other study reveals that the thicknesses and relative ordering of the quantum wells may influence the interpretation of the MQW data.
Show PACS
61.80.Jh Ion radiation effects
78.60.Hk Cathodoluminescence, ionoluminescence
81.65.-b Surface treatments

Carrier transport into intermixed GaAs/AlGaAs quantum wires

F. E. Prins, G. Lehr, E. M. Fröhlich, G. Mayer, H. Schweizer, J. Straka, A. Forchel, and G. W. Smith

Appl. Phys. Lett. 62, 1256 (1993); http://dx.doi.org/10.1063/1.108751 (3 pages) | Cited 4 times

Full Text: | Download PDF

Show Abstract
We have realized GaAs/AlGaAs quantum wires using the implantation induced intermixing technique. The transport of carriers from the AlGaAs barriers into the intermixed quantum well (QW) is studied by comparing low temperature photoluminescence spectra at resonant and nonresonant excitation. It is shown that hardly any carriers generated in the AlGaAs are captured in the intermixed QW. At resonant excitation a large lateral diffusion length of carriers from the lateral barriers into the wires is observed which is reduced at higher temperatures due to implantation defects.
Show PACS
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
78.55.Cr III-V semiconductors

Native oxide‐embedded AlyGa1−yAs‐GaAs‐InxGa1−xAs quantum well heterostructure lasers

A. R. Sugg, E. I. Chen, T. A. Richard, N. Holonyak, and K. C. Hsieh

Appl. Phys. Lett. 62, 1259 (1993); http://dx.doi.org/10.1063/1.108700 (3 pages) | Cited 26 times

Full Text: | Download PDF

Show Abstract
Data are presented on the photopumped laser operation of an AlAs‐AlyGa1−yAs‐GaAs‐InxGa1−xAs quantum well heterostructure in which the GaAs‐InxGa1−xAs active region is embedded, top and bottom, in native oxide. The upper and lower wider gap confining regions of the laser are selectively converted to oxide, leaving the active region intact. The oxidation (H2O+N2, 425 °C) proceeds laterally (perpendicular to the crystal growth direction) from a chemically etched mesa edge. The photopumped oxide‐embedded heterostructure operates as a laser continuously at 77 K and pulsed at 300 K. In comparison with the as‐grown crystal, the oxidized sample shows no significant laser threshold degradation.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
81.65.-b Surface treatments

Equilibrium multiatomic step structure of GaAs(001) vicinal surfaces grown by metalorganic chemical vapor deposition

Makoto Kasu and Naoki Kobayashi

Appl. Phys. Lett. 62, 1262 (1993); http://dx.doi.org/10.1063/1.108701 (3 pages) | Cited 63 times

Full Text: | Download PDF

Show Abstract
We have studied, in the equilibrium state, the multiatomic step (multistep) structure only a few nanometers high on GaAs(001) vicinal surfaces grown by metalorganic chemical vapor deposition (MOCVD). Annealing (growth interruption) straightens multistep edges, but even after the annealing the multistep on the [110]‐misoriented surface is straighter than the multistep on the [110]‐misoriented surface. This indicates that the free energy of the [110]‐step is lower than that of the [110]‐step. Step bunching on this vicinal surface is caused by the formation of two facets with different orientations.
Show PACS
68.35.Md Surface thermodynamics, surface energies
81.15.Kk Vapor phase epitaxy; growth from vapor phase

Ultrafast local field dynamics in photoconductive THz antennas

J. E. Pedersen, V. G. Lyssenko, J. M. Hvam, P. Uhd Jepsen, S. R. Keiding, C. B. Sørensen, and P. E. Lindelof

Appl. Phys. Lett. 62, 1265 (1993); http://dx.doi.org/10.1063/1.108702 (3 pages) | Cited 36 times

Full Text: | Download PDF

Show Abstract
We demonstrate a new ultrafast pump‐probe technique using terahertz pulses to investigate carrier transport and screening in semiconductors. As an example we have studied the temporal evolution of the local electric field in a dipole antenna, used for generation of ultrafast terahertz pulses. Ultrafast screening effects are shown to be important for both carrier transport and the emission of THz radiation. At high carrier densities the external bias field is screened on a time scale comparable to the duration of the THz pulse, giving rise to changes in the shape and bandwidth of the radiated pulses.  
Show PACS
78.47.-p Spectroscopy of solid state dynamics
72.40.+w Photoconduction and photovoltaic effects
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
72.80.Ey III-V and II-VI semiconductors

Study of the effect of Sn doping on the electronic transport properties of thin film indium oxide

Yuzo Shigesato and David C. Paine

Appl. Phys. Lett. 62, 1268 (1993); http://dx.doi.org/10.1063/1.108703 (3 pages) | Cited 72 times

Full Text: | Download PDF

Show Abstract
High quality, low resistivity (2.6×10−4 Ω cm), 0.32‐μm‐thick amorphous and polycrystalline, pure and Sn‐doped, In2O3 films prepared by high density plasma‐assisted electron beam evaporation were used to investigate the effect of Sn doping on the electronic transport properties of this material. Amorphous films with high carrier density in the as‐deposited state showed no effect of Sn doping on resistivity (ρ), Hall mobility (μ), or carrier density (n) over the range 0 to 5.3 wt % Sn. After recrystallization by annealing in air at 180 or 250 °C for 20 min, n, μ, and ρ were seen to be strongly dependent on Sn concentration in the range 0 to 1.5 wt % with a decreasing effect of Sn doping in the range 1.5 to 5.3 wt %. The data presented in this study were analyzed based on charged and neutral impurity scattering models and suggest that increasing Sn concentration leads to the formation of defect complexes which act as scattering centers but which do not contribute carriers to the material.
Show PACS
73.61.Le Other inorganic semiconductors
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Formation of As precipitates in GaAs by ion implantation and thermal annealing

A. Claverie, Fereydoon Namavar, and Z. Liliental‐Weber

Appl. Phys. Lett. 62, 1271 (1993); http://dx.doi.org/10.1063/1.108704 (3 pages) | Cited 47 times

Full Text: | Download PDF

Show Abstract
We show that it is possible to regrow an amorphous GaAs layer created by high dose As implantation at room temperature. If implantation parameters are carefully selected, As precipitates may be formed in the regrown layer with structural characteristics the same as those observed in semi‐insulating GaAs grown by molecular beam epitaxy at low temperature. Transmission electron microscopy has been used to study the structure of these precipitates in connection with the structural defects which are seen in the layer. This process appears promising for the formation of low cost semi‐insulating GaAs layers.
Show PACS
81.15.Np Solid phase epitaxy; growth from solid phases
61.72.uj III-V and II-VI semiconductors
64.75.-g Phase equilibria

Design considerations for channel‐doped back‐gated high electron mobility structures

P. M. Owen and M. Pepper

Appl. Phys. Lett. 62, 1274 (1993); http://dx.doi.org/10.1063/1.108705 (3 pages) | Cited 3 times

Full Text: | Download PDF

Show Abstract
We present the results of self‐consistent calculations for the electronic subband structure of channel‐doped, back‐gated GaAs‐AlGaAs heterostructures. The calculations identify the important design parameters for this system and illustrate the quantum effects occurring. We show that the doping density in the channel determines the mode of operation of the device and whether resonant effects are important. We discuss the design of velocity modulation transistors and structures with improved transconductance.
Show PACS
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.50.Dn Low-field transport and mobility; piezoresistance
85.30.De Semiconductor-device characterization, design, and modeling

Atomic layer etching of GaAs(110) with Br2 studied by scanning tunneling microscopy

J. C. Patrin, Y. Z. Li, M. Chander, and J. H. Weaver

Appl. Phys. Lett. 62, 1277 (1993); http://dx.doi.org/10.1063/1.108706 (3 pages) | Cited 17 times

Full Text: | Download PDF

Show Abstract
Scanning tunneling microscopy studies of GaAs(110) exposed to Br2 at 720 K show preferential etching at single‐height [112] and [001] steps with little etching at double‐height steps. Etching in the [110] direction is at least ∼4.5 times faster than in the [001] direction, producing rectangular etch pits. For higher Br2 exposures, etching is dominated by single‐height step flow but triangular double‐layer etch pits also form on extended terraces.
Show PACS
81.65.-b Surface treatments
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces

Comparison between different schemes for passivation of multicrystalline silicon solar cells by means of hydrogen plasma and front side oxidation

M. Ghannam, G. Palmers, H. E. Elgamel, J. Nijs, R. Mertens, R. Peruzzi, and D. Margadonna

Appl. Phys. Lett. 62, 1280 (1993); http://dx.doi.org/10.1063/1.108707 (3 pages) | Cited 9 times

Full Text: | Download PDF

Show Abstract
Different schemes for passivation of solar cells fabricated using casted multicrystalline silicon from Eurosolare are investigated. The efficiency of solar cells with front side oxide surface passivation, front side and/or back side hydrogen plasma passivation are compared. It is shown that oxide passivation of the front surface combined with hydrogen passivation from the back side is the optimum passivation scheme. A 16.2% top efficiency is obtained on 4 cm2 cells implementing this passivation scheme and a 16.8% top efficiency is estimated with an optimized ARC combination.
Show PACS
84.60.Jt Photoelectric conversion
81.65.-b Surface treatments

Room‐temperature determination of two‐dimensional electron gas concentration and mobility in heterostructures

S. E. Schacham, R. A. Mena, E. J. Haugland, and S. A. Alterovitz

Appl. Phys. Lett. 62, 1283 (1993); http://dx.doi.org/10.1063/1.108708 (3 pages) | Cited 12 times

Full Text: | Download PDF

Show Abstract
A technique for determination of room‐temperature two‐dimensional electron gas (2DEG) concentration and mobility in heterostructures is presented. Using simultaneous fits of the longitudinal and transverse voltages as a function of applied magnetic field, we were able to separate the parameters associated with the 2DEG from those of the parallel layer. Comparison with the Shubnikov–de Haas data derived from measurements at liquid helium temperatures proves that the analysis of the room‐temperature data provides an excellent estimate of the 2DEG concentration. In addition we were able to obtain for the first time the room‐temperature mobility of the 2DEG, an important parameter to device application. Both results are significantly different from those derived from conventional Hall analysis.
Show PACS
73.50.Dn Low-field transport and mobility; piezoresistance
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

Bias‐stress‐induced stretched‐exponential time dependence of charge injection and trapping in amorphous thin‐film transistors

F. R. Libsch and J. Kanicki

Appl. Phys. Lett. 62, 1286 (1993); http://dx.doi.org/10.1063/1.108709 (3 pages) | Cited 131 times

Full Text: | Download PDF

Show Abstract
The threshold voltage instabilities in nitride/oxide dual gate dielectric hydrogenated amorphous silicon (a‐Si:H) thin‐film transistors are investigated as a function of stress time, stress temperature, and stress bias. The obtained results are explained with a multiple trapping model rather than weak bond breaking model. In our model, the injected carriers from the a‐Si:H channel first thermalize in a broad distribution of localized band‐tail states located at the a‐Si:H/aSiNx:H interface and in the a‐SiNx:H transitional layer close to the interface, then move to deeper energies in amorphous silicon nitride at longer stress times, larger stress electric fields, or higher stress temperatures. The obtained bias‐stress‐temperature induced threshold voltage shifts are accurately modeled with a stretched‐exponential stress time dependence where the stretched‐exponent β cannot be related to the β=TST/T0 but rather to β≂TST/T0∗−β0 for TST≤80 °C; for TST≥80 °C, the β is stress temperature independent. We have also found that β is stress gate bias independent.
Show PACS
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
73.61.Jc Amorphous semiconductors; glasses
71.55.Jv Disordered structures; amorphous and glassy solids
85.30.Tv Field effect devices

High critical current densities in ultrathin YBa2Cu3O7−δ films sandwiched between (PrxY1−x)Ba2Cu3O7−δ layers

C. Kwon, Qi Li, X. X. Xi, S. Bhattacharya, C. Doughty, T. Venkatesan, H. Zhang, J. W. Lynn, J. L. Peng, Z. Y. Li, N. D. Spencer, and K. Feldman

Appl. Phys. Lett. 62, 1289 (1993); http://dx.doi.org/10.1063/1.108710 (3 pages) | Cited 19 times

Full Text: | Download PDF

Show Abstract
YBa2Cu3O7−δ (YBCO) films with nominal thicknesses of 1–4 unit cells were grown by pulsed laser deposition using (PrxY1−x)Ba2Cu3O7−δ [(PrxY1−x)BCO] (1≥x≥0) as buffer layers and cap layers. The films of 1 unit cell thick were superconducting for all the x values while Tc increased when x was reduced. For adjacent layers of (Pr0.6Y0.4)BCO which is semiconducting, a Tc of 43 K and Jc of 2×106 A/cm2 for B∥ab and 4×105 A/cm2 for B⊥ab at B=7 T and 4.2 K were obtained in a one‐unit cell thick YBCO layer. The Jc values of a few unit cell thick YBCO layers nearly approached that of thick YBCO films. The results suggest the absence of significant weak‐link effects in these films.
Show PACS
74.78.-w Superconducting films and low-dimensional structures
74.72.-h Cuprate superconductors
74.25.Uv Vortex phases (includes vortex lattices, vortex liquids, and vortex glasses)

Screw dislocations in substrates used for high temperature superconductor thin films

D. Eissler, H. S. Wang, and W. Dietsche

Appl. Phys. Lett. 62, 1292 (1993); http://dx.doi.org/10.1063/1.108711 (3 pages) | Cited 3 times

Full Text: | Download PDF

Show Abstract
Substrates for high temperature superconductor (HTSC) thin films were chemically etched in order to obtain pits and hillocks at the sites of the dislocations. The structures were imaged by both an atomic force microscope and an optical microscope. We found that the dislocation density in the bare substrate is comparable to the screw dislocation density in the HTSC films. Based on the shape and orientation of the pits we identify the defects in the substrate as screw dislocations.  
Show PACS
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
74.78.-w Superconducting films and low-dimensional structures

Millimeter‐wave response and linewidth of Josephson oscillations in YBa2Cu3O7 step‐edge junctions

Yu. Ya. Divin, A. V. Andreev, G. M. Fischer, J. Mygind, N. F. Pedersen, K. Herrmann, V. N. Glyantsev, M. Siegel, and A. I. Braginski

Appl. Phys. Lett. 62, 1295 (1993); http://dx.doi.org/10.1063/1.108712 (3 pages) | Cited 7 times

Full Text: | Download PDF

Show Abstract
We have studied the response of YBa2Cu3O7 step‐edge junctions to low‐intensity millimeter‐wave radiation in the temperature range from 4 to 80 K. The linewidth of the Josephson oscillations derived from the resonant part of the response at voltages V≂(h/2e)f is shown to be determined by thermal fluctuations at liquid nitrogen temperatures. At lower temperatures the observed linewidth increases indicating that low‐frequency fluctuations become dominant in the junction as the temperature is reduced. Due to an inhomogeneous spatial distribution of the current the step‐edge junction might be considered as a multijunction multiloop interferometer and the excess noise can be discussed in terms of spontaneous transitions between the different states of these interferometers.
Show PACS
74.50.+r Tunneling phenomena; Josephson effects
74.81.Bd Granular, melt-textured, amorphous, and composite superconductors
74.72.-h Cuprate superconductors

80–111 GHz quasi‐optical measurement of the complex conductivities of YBa2Cu3O7 superconducting thin films

Dawei Zhang, D. V. Plant, H. R. Fetterman, N. E. Glass, J. T. Cheung, and P. H. Kobrin

Appl. Phys. Lett. 62, 1298 (1993); http://dx.doi.org/10.1063/1.108713 (3 pages) | Cited 5 times

Full Text: | Download PDF

Show Abstract
Complex conductivities of YBa2Cu3O7 high‐temperature superconducting thin films were measured from 80 to 111 GHz using quasi‐optical techniques. From transmission measurements, a peak was obtained in σ1 versus temperature. Measurements of the frequency dependence of this peak position found it shifted to higher temperatures with increasing frequency. The data for both σ1 and σ2, as a function of frequency, were fitted using a BCS/effective medium model. This fit indicates that the observed peak in σ1 is a result of the temperature dependence of the carrier mean free path combined with effects resulting from the granularity of the films.
Show PACS
74.25.N- Response to electromagnetic fields
74.78.-w Superconducting films and low-dimensional structures
74.72.-h Cuprate superconductors

Short‐pulse scattering measurements from dielectric spheres using photoconductively switched antennas

David Kralj and Lawrence Carin

Appl. Phys. Lett. 62, 1301 (1993); http://dx.doi.org/10.1063/1.108714 (3 pages) | Cited 2 times

Full Text: | Download PDF

Show Abstract
Planar antennas are switched photoconductively using optical pulses generated by a picosecond laser system. The freely propagating radiation, of picosecond duration and with bandwidth extending from 5 to 75 GHz, is used to perform short‐pulse scattering measurements on three‐dimensional targets. Results are shown for scattering from dielectric spheres, with the time‐domain results clearly showing the early and late‐time scattered signal. All measurements are compared with theory, directly in the time domain.
Show PACS
41.20.Jb Electromagnetic wave propagation; radiowave propagation
Page 2 of 2 Pages Previous Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close