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26 Jan 1998

Volume 72, Issue 4, pp. 395-509

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Alloying effects on the critical layer thickness in InxGa1−xAs/InP heterostructures analyzed by Raman scattering

P. S. Pizani, T. M. Boschi, F. Lanciotti, J. Groenen, R. Carles, P. Maigné, and M. Gendry

Appl. Phys. Lett. 72, 436 (1998); http://dx.doi.org/10.1063/1.120800 (3 pages) | Cited 8 times

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Raman scattering has been used to estimate the critical layer thickness and to analyze the alloying effect on strain relaxation in InxGa1−xAs layers grown by molecular beam epitaxy on InP [001]-oriented substrate, for x ranging from 0.0 to 1.0. Measurements of longitudinal optical GaAs-like phonon frequency and Raman linewidth showed that the indium/gallium ratio contents greatly influences the strain relaxation. A comparison between Raman and x-ray diffraction measurements of relaxation ratios as a function of layer thickness is presented. The results can be explained in terms of the combined effect of strain and chemical and structural disorder. © 1998 American Institute of Physics.
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68.60.Bs Mechanical and acoustical properties
68.55.-a Thin film structure and morphology
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
78.66.Fd III-V semiconductors
78.30.Fs III-V and II-VI semiconductors

Trapping and recombination dynamics of low-temperature-grown InGaAs/InAlAs multiple quantum wells

Yue Chen, S. S. Prabhu, Stephen E. Ralph, and Dave T. McInturff

Appl. Phys. Lett. 72, 439 (1998); http://dx.doi.org/10.1063/1.120766 (3 pages) | Cited 21 times

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We have observed a long-lived residual photoconductivity in low-temperature-grown (LT) InGaAs. These results have significant consequences for devices comprised of LT-InGaAs, other defect moderated materials, and standard-temperature-grown InGaAs. Our investigation utilizes time-resolved terahertz conductivity to quantify the trapping and recombination rates of LT Be-doped In0.53Ga0.47As/In0.52Al0.48As multiple quantum wells and bulk InGaAs. It is found that Be doping reduces the residual photoconductivity and increases the initial electron trapping rate. These results are in contrast to those observed via transient absorption studies, which suggest that these systems have returned to equilibrium after the initial transient. Furthermore, a 600 °C anneal increases both the trapping and recombination rate in all Be-doped samples. © 1998 American Institute of Physics.
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73.61.Ey III-V semiconductors
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
72.40.+w Photoconduction and photovoltaic effects
73.50.Pz Photoconduction and photovoltaic effects
72.30.+q High-frequency effects; plasma effects
73.50.Mx High-frequency effects; plasma effects

The behavior of As precipitates in low-temperature-grown GaAs

J. C. Bourgoin, K. Khirouni, and M. Stellmacher

Appl. Phys. Lett. 72, 442 (1998); http://dx.doi.org/10.1063/1.120781 (3 pages) | Cited 10 times

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We analyze the kinetics associated with the concentration and the growth of As precipitates during annealing in low-temperature-grown GaAs layers. We correlate them with that associated with the annealing of the As antisite related defect. This allows us to deduce that all these kinetics are governed by the mobility of the As interstitial whose migration energy is 0.44 eV. © 1998 American Institute of Physics.  
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81.30.Mh Solid-phase precipitation
64.75.-g Phase equilibria
81.40.Gh Other heat and thermomechanical treatments
61.72.Cc Kinetics of defect formation and annealing
61.72.J- Point defects and defect clusters
66.30.H- Self-diffusion and ionic conduction in nonmetals

A 3 kV Schottky barrier diode in 4H-SiC

Q. Wahab, T. Kimoto, A. Ellison, C. Hallin, M. Tuominen, R. Yakimova, A. Henry, J. P. Bergman, and E. Janzén

Appl. Phys. Lett. 72, 445 (1998); http://dx.doi.org/10.1063/1.120782 (3 pages) | Cited 29 times

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High-voltage Schottky barrier diodes with low reverse leakage current were processed on hot-wall chemical vapor deposition grown 4H-SiC films. A metal overlap onto the oxide layer was employed to reduce electric field crowding at the contact periphery. By utilizing a 42–47 μm thick, high-quality epitaxial layers with doping in the range of 7×1014–2×1015 cm−3, a record blocking voltage of above 3 kV was achieved. The large diodes with 1.0 mm diameter showed breakdown at 2.1 kV. The reverse leakage current density at 1.0 kV was measured to be 7.0×10−7 A cm−2. Specific on-resistance of the diode with breakdown voltage at 3 kV was 34 mΩ cm2. © 1998 American Institute of Physics.
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85.30.Kk Junction diodes
85.30.Hi Surface barrier, boundary, and point contact devices
77.22.Jp Dielectric breakdown and space-charge effects

Electron-irradiation-induced deep level in n-type GaN

Z.-Q. Fang, J. W. Hemsky, D. C. Look, and M. P. Mack

Appl. Phys. Lett. 72, 448 (1998); http://dx.doi.org/10.1063/1.120783 (2 pages) | Cited 54 times

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Deep-level transient spectroscopy measurements of n-type GaN epitaxial layers irradiated with 1-MeV electrons reveal an irradiation-induced electron trap at EC−0.18 eV. The production rate is approximately 0.2 cm−1, lower than the rate of 1 cm−1 found for the N vacancy by Hall-effect studies. The defect trap cannot be firmly identified at this time. © 1998 American Institute of Physics.
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71.55.Eq III-V semiconductors
73.61.Ey III-V semiconductors
61.80.Fe Electron and positron radiation effects
61.72.J- Point defects and defect clusters
72.20.My Galvanomagnetic and other magnetotransport effects
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
72.80.Ey III-V and II-VI semiconductors

On the behavior of deuterium in ultrathin SiO2 films upon thermal annealing

I. J. R. Baumvol, E. P. Gusev, F. C. Stedile, F. L. Freire, M. L. Green, and D. Brasen

Appl. Phys. Lett. 72, 450 (1998); http://dx.doi.org/10.1063/1.120801 (3 pages) | Cited 18 times

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Following the observation of the large isotopic effect in D2 passivated gate dielectrics [J. Lyding, K. Hess, and I. C. Kizilyalli, Appl. Phys. Lett. 68, 2526 (1996)], we studied the behavior of deuterium in ultrathin SiO2 films by nuclear reaction analysis techniques. Accurate concentrations of deuterium in the films, deuterium depth distributions, and deuterium removal from the film upon thermal annealing in vacuum have been examined. For D2 passivated films, we found rather high concentrations of deuterium near the SiO2/Si interface, well above both the solubility of deuterium in silica and the maximum concentration of electrically active defects at the interface. Our results suggest a complex multistep mechanism of thermally activated deuterium removal from the film, which probably consists of D detrapping, diffusion, and desorption steps. © 1998 American Institute of Physics.
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68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
61.72.Cc Kinetics of defect formation and annealing
81.40.Gh Other heat and thermomechanical treatments
81.65.Rv Passivation
82.80.Jp Activation analysis and other radiochemical methods
61.72.S- Impurities in crystals
68.35.Ct Interface structure and roughness
64.75.-g Phase equilibria
66.30.J- Diffusion of impurities
68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics

Energy resolved noise measurements in quantum well infrared photodetectors

J. Yao, C. J. Chen, K. K. Choi, W. H. Chang, and D. C. Tsui

Appl. Phys. Lett. 72, 453 (1998); http://dx.doi.org/10.1063/1.120784 (3 pages) | Cited 2 times

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In quantum well infrared photodetectors, the detector dark current usually is composed of a wide range of energies originated from thermionic emission as well as thermally assisted tunneling. Yet, it is a common practice to assign a single noise gain to all electrons irrespective of their energies. This assigned value can only represent the mean since both the hot-electron lifetime and the transit time, whose ratio determines the gain, are energy dependent. In this work, we have resolved the energy dependence of the noise gain using an electron energy filter. We find that although the noise gain increases initially with energy as expected, it reaches a maximum at 0.27 eV above the GaAs conduction band edge, and then decreases and forms a minimum at 0.31 eV. We attribute this decrease to the Γ-L intervalley scattering, which increases the transit time of the electrons. © 1998 American Institute of Physics.
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85.60.Gz Photodetectors (including infrared and CCD detectors)
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
79.40.+z Thermionic emission
72.20.Ht High-field and nonlinear effects
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
72.70.+m Noise processes and phenomena
73.61.Ey III-V semiconductors

Hydrogen abstraction kinetics and crystallization in low temperature plasma deposition of silicon

Easwar Srinivasan and Gregory N. Parsons

Appl. Phys. Lett. 72, 456 (1998); http://dx.doi.org/10.1063/1.120785 (3 pages) | Cited 20 times

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Exposing a plasma deposited hydrogenated silicon layer to atomic hydrogen results in hydrogen removal from the silicon/hydrogen surface and a net reduction in the total hydrogen content in the layer. For deposition at low temperature, the crystallization fraction corresponds directly with the extent of hydrogen removal. Silicon films deposited using alternating deposition and hydrogen (or deuterium) plasma exposure are characterized by transmission infrared spectroscopy and Raman spectroscopy. Using mass spectroscopy, hydrogen abstraction and etching are observed and identified as important pathways for hydrogen removal at substrate temperatures between 25 °C and 300 °C. Moreover, the hydrogen abstraction kinetics show that the reaction is first order with an activation barrier of −0.4±1 kcal/mol, consistent with a spontaneous Eley–Rideal abstraction process. Energy barrier values are supported by ab initio calculations. © 1998 American Institute of Physics.
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81.05.Cy Elemental semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
78.30.Am Elemental semiconductors and insulators
78.66.Db Elemental semiconductors and insulators

Doping of AlxGa1−xN

C. Stampfl and Chris G. Van de Walle

Appl. Phys. Lett. 72, 459 (1998); http://dx.doi.org/10.1063/1.120803 (3 pages) | Cited 59 times

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N-type AlxGa1−xN exhibits a dramatic decrease in the free-carrier concentration for x ≥ 0.40. Based on first-principles calculations, we propose that two effects are responsible for this behavior: (i) in the case of doping with oxygen (the most common unintentional donor), a DX transition occurs, which converts the shallow donor into a deep level; and (ii) compensation by the cation vacancy (VGa or VAl), a triple acceptor, increases with alloy composition x. For p-type doping, the calculations indicate that the doping efficiency decreases due to compensation by the nitrogen vacancy. In addition, an increase in the acceptor ionization energy is found with increasing x. © 1998 American Institute of Physics.
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61.72.uj III-V and II-VI semiconductors
61.72.J- Point defects and defect clusters
71.55.Eq III-V semiconductors
72.80.Ey III-V and II-VI semiconductors
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

Excess silicon at the Si3N4/SiO2 interface

V. A. Gritsenko, I. P. Petrenko, S. N. Svitasheva, and Hei Wong

Appl. Phys. Lett. 72, 462 (1998); http://dx.doi.org/10.1063/1.120786 (3 pages) | Cited 12 times

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Using electron energy loss spectroscopy, X-ray photoelectronic spectroscopy, and ellipsometry measurements, a large number of Si-Si bonds at the Si3N4/thermal SiO2 interface is confirmed. After etching away the surface SiO2 of reoxidized Si3N4, we found at the Si3N4/SiO2 interface that the plasmon energy on the surface is 20 eV which is smaller than the bulk plasmon of either Si3N4 (24.0 eV) or SiO2 (23.0 eV). From ellipsometric measurement, a large value of the refractive index (n = 2.1) in the Si3N4/ wet SiO2 interface layer was obtained. The effective width of the Si-rich interfacial layer is estimated to be in the range of 6–8 Å. We propose that the excess silicon at the Si3N4/SiO2 interface is created by replacing nitrogen atoms with the oxygen atoms during the oxidation of Si3N4. Based on these observations and on numerical simulation, a hypothesis is proposed to explain the abnormally large electron capturing at the Si3N4/SiO2 interface observed previously and the accumulation of positive charge at the top interface of the nitrided oxide under ionizing irradiation. © 1998 American Institute of Physics.
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79.60.Jv Interfaces; heterostructures; nanostructures
79.20.Kz Other electron-impact emission phenomena
61.85.+p Channeling phenomena (blocking, energy loss, etc.)
68.35.Ct Interface structure and roughness
81.65.Cf Surface cleaning, etching, patterning
81.65.Mq Oxidation
81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)

Stacked GaAs multi-quantum wires grown on vicinal GaAs(110) surfaces by molecular beam epitaxy

Takehiko Kato, Toshikazu Takeuchi, Yoshiji Inoue, Shigehiko Hasegawa, Koichi Inoue, and Hisao Nakashima

Appl. Phys. Lett. 72, 465 (1998); http://dx.doi.org/10.1063/1.120787 (3 pages) | Cited 10 times

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Stacked GaAs quantum wires (QWRs) are grown on the surfaces with giant steps which are naturally formed on vicinal GaAs(110) substrates by molecular beam epitaxy. Transmission electron microscopy observation clearly shows stacked structures of coherently aligned quantum wires which are induced by GaAs layer thickness modulation at the step edges. Photoluminescence peak shifts with the thickness of the AlGaAs barrier layers are explained as due to the coupling between the QWRs. © 1998 American Institute of Physics.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
81.05.Ea III-V semiconductors
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
78.66.Fd III-V semiconductors
78.55.Cr III-V semiconductors

Deep levels in Er-doped liquid phase epitaxy grown silicon

A. Cavallini, B. Fraboni, and S. Pizzini

Appl. Phys. Lett. 72, 468 (1998); http://dx.doi.org/10.1063/1.120788 (3 pages) | Cited 9 times

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The optical activity of Er-doped silicon is related to the presence of defects which enhance the typical radiative transition at 0.8 eV but whose nature and properties are still largely unknown. We have investigated the deep levels present in Er-doped liquid phase epitaxy silicon to identify the traps possibly related to the luminescence. Among the observed levels, two minority carrier traps labeled E2 (EC−0.20 eV) and E3 (EC−0.39 eV), and one majority carrier trap labeled H1 (Ev+0.32 eV) are good candidates for the material optical activity. The onset of luminescence occurs after a thermal treatment and is accompanied by a high space charge density localization at the epilayer-substrate interface. © 1998 American Institute of Physics.
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73.61.Cw Elemental semiconductors
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
81.15.Lm Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids)
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
81.05.Cy Elemental semiconductors
73.20.Hb Impurity and defect levels; energy states of adsorbed species
78.66.Db Elemental semiconductors and insulators
78.55.Ap Elemental semiconductors

High bias transport and magnetometer design in open quantum dots

M. Switkes, A. G. Huibers, C. M. Marcus, K. Campman, and A. C. Gossard

Appl. Phys. Lett. 72, 471 (1998); http://dx.doi.org/10.1063/1.120789 (3 pages) | Cited 8 times

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We report transport measurements as a function of bias in open semiconductor quantum dots. These measurements are well described by an effective electron temperature derived from Joule heating at the point contacts and cooling by Wiedemann-Franz out-diffusion of thermal electrons. Using this model, we propose and analyze a quantum dot based sensor capable of measuring absolute magnetic field at micron scales with a noise floor of ∼ 110 nT/math at 300 mK. Non optimized measurements reported here are ∼ 2 orders of magnitude above this floor. © 1998 American Institute of Physics.
Show PACS
73.61.Ey III-V semiconductors
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
85.35.Ds Quantum interference devices
07.55.Ge Magnetometers for magnetic field measurements
73.50.Fq High-field and nonlinear effects

The dissociation energy and the charge state of a copper-pair center in silicon

A. A. Istratov, H. Hieslmair, T. Heiser, C. Flink, and E. R. Weber

Appl. Phys. Lett. 72, 474 (1998); http://dx.doi.org/10.1063/1.120790 (3 pages) | Cited 23 times

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Thermal dissociation of Cu pairs was studied in p-type silicon. The dissociation energy of the Cu pair was found to be 1.02±0.07 eV, twice as high as the binding energy of a Coulombically bound donor-acceptor pair placed on nearest neighbor 〈111〉 sites. This implies that the pair is either covalently bonded, or it consists of an ionically bonded doubly negatively charged acceptor and a singly charged donor. To distinguish between these two models, the dependence of the hole emission rate on the electric field in the depletion region was studied. The absence of the Pool-Frenkel emission enhancement ruled out the acceptor nature of the center and the purely ionic type of bonding. On the other hand, the polarization potential describing emission from a neutral impurity gave a satisfactory fit to the experimental data. It is concluded that the Cu pair is a donor with either covalent or mixed type of bonding. © 1998 American Institute of Physics.
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71.55.Cn Elemental semiconductors
72.20.Ht High-field and nonlinear effects
72.80.Cw Elemental semiconductors

D–Si(111)(1×1) surface for the study of silicon etching in aqueous solutions

Huihong Luo and Christopher E. D. Chidsey

Appl. Phys. Lett. 72, 477 (1998); http://dx.doi.org/10.1063/1.120791 (3 pages) | Cited 12 times

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Deuterium-terminated Si(111) surfaces are formed in a solution of KF and DCl in D2O. Infrared spectroscopy shows the surface to be flat with a D–Si bond normal to the surface. H–Si is formed preferentially to D–Si in a mixture of protonated and deuterated etchants. From the D-to-H exchange rate and the terrace width, we estimate the rate of the stepflow etching process to be 4.2 nm/s in Ar-sparged 40% NH4F solution. Dissolved O2 in the solutions substantially increases the D-to-H exchange rate by the formation of pits and the consequent increase in the step density. © 1998 American Institute of Physics.
Show PACS
81.05.Cy Elemental semiconductors
81.65.Cf Surface cleaning, etching, patterning
78.30.Am Elemental semiconductors and insulators
68.35.B- Structure of clean surfaces (and surface reconstruction)
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