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12 Feb 2001

Volume 78, Issue 7, pp. 853-1016

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Piezoelectric-field-enhanced lateral ambipolar diffusion coefficient in InGaN/GaN multiple quantum wells

Yin-Chieh Huang, Jian-Chin Liang, Chi-Kuang Sun, Amber Abare, and Steven P. DenBaars

Appl. Phys. Lett. 78, 928 (2001); http://dx.doi.org/10.1063/1.1347399 (3 pages) | Cited 5 times

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Lateral diffusion behavior of two-dimensional carrier gas in InGaN/GaN multiple quantum wells was investigated using optical transient transmission measurements. A large ambipolar diffusion coefficient was observed, which was attributed to the enhancement by a strong piezoelectric field. This large ambipolar diffusion coefficient was found to increase with increased well width with a value on the order of 3000 cm2/s for a 62 Å well-width sample. © 2001 American Institute of Physics.
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73.63.Hs Quantum wells
78.67.De Quantum wells
77.65.Ly Strain-induced piezoelectric fields
73.50.Dn Low-field transport and mobility; piezoresistance

Dynamic quantum-confined stark effect in self-assembled InAs quantum dots

M. Gurioli, S. Sanguinetti, and M. Henini

Appl. Phys. Lett. 78, 931 (2001); http://dx.doi.org/10.1063/1.1348305 (3 pages) | Cited 12 times

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We present a detailed investigation of the carrier dynamics in a set of InAs/GaAs (N11) quantum dots (QD) by means of time-resolved photoluminesce (PL) techniques. A dynamical red shift of the PL bands when increasing the delay time after the pulse excitation is observed. We attribute this intrinsic optical nonlinearity to the photoinduced screening of internal built-in electric field. The value of the redshift of the QD emission band decays with the carrier population demonstrating the intrinsic nature of the built-in field. Its dependence on the substrate orientation and termination agrees with the expected piezoelectric induced quantum confined Stark effects of the QD optical transitions. © 2001 American Institute of Physics.
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78.20.Jq Electro-optical effects
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
78.67.Hc Quantum dots
78.47.-p Spectroscopy of solid state dynamics

Ultralarge capacitance–voltage hysteresis and charge retention characteristics in metal oxide semiconductor structure containing nanocrystals deposited by ion-beam-assisted electron beam deposition

Yong Kim, Kyung Hwa Park, Tae Hun Chung, Hong Jun Bark, Jae-Yel Yi, Won Chel Choi, Eun Kyu Kim, Ju Wook Lee, and Jeong Yong Lee

Appl. Phys. Lett. 78, 934 (2001); http://dx.doi.org/10.1063/1.1337618 (3 pages) | Cited 29 times

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Amorphous silicon films are deposited by ion-beam-assisted electron beam deposition and subsequently oxidized by a rapid thermal oxidation process. The oxidized film contains a large density of nanocrystals specifically localized at a certain depth from the Si/SiOx interface, whereas no evidence of nanocrystals is found for oxidized films deposited without ion beam assistance. Such a marked contrast resulted from the enhancement of nucleation rate by ion beam irradiation. The metal-oxide-semiconductor structure utilizing the film shows an ultralarge capacitance–voltage hysteresis whose width is over 20 V. In addition capacitance–time measurement shows a characteristic capacitance transient indicating nondispersive carrier relaxation. The retention time shows a dependence on applied bias and the maximum time of ∼70 s is obtained near midgap voltage. The retention time dependence on applied bias and large capacitance–voltage hysteresis are attributed to direct tunneling of trapped charges in the deep traps of nanocrystals to the interface states. © 2001 American Institute of Physics.
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73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
73.22.-f Electronic structure of nanoscale materials and related systems
81.65.Mq Oxidation
81.15.Jj Ion and electron beam-assisted deposition; ion plating
61.80.Jh Ion radiation effects
81.07.Bc Nanocrystalline materials
73.20.Hb Impurity and defect levels; energy states of adsorbed species
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths

Infrared response of multiple-component free-carrier plasma in heavily doped p-type GaAs

S. Zangooie, M. Schubert, D. W. Thompson, and J. A. Woollam

Appl. Phys. Lett. 78, 937 (2001); http://dx.doi.org/10.1063/1.1343490 (3 pages) | Cited 4 times

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Spectroscopic ellipsometry is used to measure the dielectric function of heavily doped p-type GaAs for wave numbers from 100 to 2000 cm−1. Due to partial filling of the heavy- and light-hole valence bands, heavy holes as well as light holes form a multiple-component plasma coupled with longitudinal optical phonons. Line-shape analysis of the infrared response allows differentiating between light- and heavy-hole contributions to the carrier plasma, and the results observed suggest nonparabolicity effects of the heavy- and light-hole valence bands in GaAs. © 2001 American Institute of Physics.
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78.30.Fs III-V and II-VI semiconductors
71.45.Gm Exchange, correlation, dielectric and magnetic response functions, plasmons
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
63.20.-e Phonons in crystal lattices

Atomistic simulations of extrinsic defects evolution and transient enhanced diffusion in silicon

B. Colombeau, F. Cristiano, A. Altibelli, C. Bonafos, G. Ben Assayag, and A. Claverie

Appl. Phys. Lett. 78, 940 (2001); http://dx.doi.org/10.1063/1.1344566 (3 pages) | Cited 13 times

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In this letter, a physically based model describing the kinetic evolution of extrinsic defects during annealing is presented. The fundamental concepts of Ostwald ripening and formation energy of extrinsic defects are combined in this model, which has been tested against some classical experiments concerning (i) transient enhanced diffusion (TED) of dopants in conjunction with the dissolution of {113} defects and (ii) the “pulsed” TED observed in the case of ultralow energy implants where the surface acts as a strong sink for the silicon interstitial atoms. We show that a full understanding of the formation and the evolution of extended defects leads to a correct prediction of dopant enhanced diffusion in all experimental conditions. © 2001 American Institute of Physics.
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66.30.Dn Theory of diffusion and ionic conduction in solids
81.05.Cy Elemental semiconductors
66.30.Lw Diffusion of other defects
61.72.Cc Kinetics of defect formation and annealing
81.40.Gh Other heat and thermomechanical treatments
61.72.J- Point defects and defect clusters

Electrical isolation of GaN by MeV ion irradiation

H. Boudinov, S. O. Kucheyev, J. S. Williams, C. Jagadish, and G. Li

Appl. Phys. Lett. 78, 943 (2001); http://dx.doi.org/10.1063/1.1348306 (3 pages) | Cited 13 times

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The evolution of sheet resistance of n-type GaN epilayers exposed to irradiation with MeV H, Li, C, and O ions is studied in situ. Results show that the threshold dose necessary for complete isolation linearly depends on the original free electron concentration and reciprocally depends on the number of atomic displacements produced by ion irradiation. Furthermore, such isolation is stable to rapid thermal annealing at temperatures up to 900 °C. In addition to providing a better understanding of the physical mechanisms responsible for electrical isolation, these results can be used for choosing implant conditions necessary for an effective electrical isolation of GaN-based devices. © 2001 American Institute of Physics.
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73.61.Ey III-V semiconductors
61.72.Cc Kinetics of defect formation and annealing
61.80.Jh Ion radiation effects

Operation of a three-junction single-electron pump with on-chip resistors

S. V. Lotkhov, S. A. Bogoslovsky, A. B. Zorin, and J. Niemeyer

Appl. Phys. Lett. 78, 946 (2001); http://dx.doi.org/10.1063/1.1347017 (3 pages) | Cited 40 times

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We report on the operation of a single-electron pump (comprising three Al/AlOx/Al tunnel junctions and two gates) connected to the bias electrodes through the compact on-chip Cr resistors, R ≈ 60 kΩ>Rk = h/e2 ≈ 26 kΩ. The function of the resistors in this so-called R pump was to suppress electron cotunneling, the process which otherwise severely deteriorates the performance of few-junction single-electron devices. When a harmonic ac drive of frequency f of several MHz was applied to the gates, the current–voltage curve of the R pump exhibited remarkably horizontal current steps at I = ef. We show that the use of the resistors is capable of substantially increasing the accuracy of the pump in comparison to operation of the pump without resistors. © 2001 American Institute of Physics.
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85.25.Am Superconducting device characterization, design, and modeling
85.35.Gv Single electron devices

Hole-trapping-related transients in shallow n+–p junctions fabricated in a high-energy boron-implanted p well

A. Poyai, E. Simoen, and C. Claeys

Appl. Phys. Lett. 78, 949 (2001); http://dx.doi.org/10.1063/1.1342041 (3 pages) | Cited 3 times

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This letter describes a transient phenomenon in the reverse hole current of large-area shallow n+–p-well junctions, giving rise to a hump at a specific reverse bias. This corresponds to a certain depletion depth in the retrograde p well, which has been fabricated by a deep (200 keV) and a shallow (55 keV) boron ion implantation. No such a reverse hole current hump occurs for reference diodes, processed in p-type Czochralski substrates. The effect is also absent in large-perimeter p-well junctions, suggesting a correlation with defects in the p-well region. The occurrence at a specific depletion depth indicates a nonuniform defect distribution, for example related to the displacement damage created by the 200 keV B implantation. This idea is further supported by deep level transient spectroscopy results, which reveal the presence of a nonuniform density of hole traps, corresponding to a broad range of energy levels from about 0.3 to 0.5 eV above the valence band. A discussion of the possible nature of the underlying defects is given. © 2001 American Institute of Physics.
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73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
61.72.uf Ge and Si
85.30.Kk Junction diodes
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
73.63.Hs Quantum wells

Correlation of defect profiles with carrier profiles of InAs epilayers on GaP

H. Tsukamoto, E.-H. Chen, J. M. Woodall, and V. Gopal

Appl. Phys. Lett. 78, 952 (2001); http://dx.doi.org/10.1063/1.1338956 (3 pages) | Cited 1 time

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The carrier profile for InAs films grown on GaP is modeled as a first-order approximation which assumes that 90° edge dislocation intersections and the threading dislocation intersections act as shallow donors. Due to dislocation annihilation during growth, the threading dislocation intersection density decreases as the inverse of the distance x from the InAs/GaP interface, D(x) = D0x0/(x0+x), where D0 and x0 are dislocation density at the InAs/GaP interface and the first annihilation position from the interface, respectively. The carrier profile in InAs films can be described by a similar equation that is deduced from the threading dislocation intersection profile. The calculated carrier profiles agree well with measured carrier profiles. This correlation supports our hypothesis that both the edge dislocation intersections and the threading dislocation intersections act as shallow donor sources. © 2001 American Institute of Physics.
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68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
73.61.Ey III-V semiconductors
71.55.Eq III-V semiconductors
68.35.Dv Composition, segregation; defects and impurities
73.20.Hb Impurity and defect levels; energy states of adsorbed species
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
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