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17 Feb 1997

Volume 70, Issue 7, pp. 793-912

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“Plug and play” systems for quantum cryptography

A. Muller, T. Herzog, B. Huttner, W. Tittel, H. Zbinden, and N. Gisin

Appl. Phys. Lett. 70, 793 (1997); http://dx.doi.org/10.1063/1.118224 (3 pages) | Cited 126 times

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We present a time-multiplexed interferometer based on Faraday mirrors, and apply it to quantum key distribution. The interfering pulses follow exactly the same spatial path, ensuring very high stability and self balancing. The use of Faraday mirrors compensates automatically any birefringence effects and polarization dependent losses in the transmitting fiber. First experimental results show a fringe visibility of 0.9984 for a 23-km-long interferometer, based on installed telecom fibers. © 1997 American Institute of Physics.
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03.65.-w Quantum mechanics
07.60.Ly Interferometers
42.79.Sz Optical communication systems, multiplexers, and demultiplexers

Analysis of temperature sensitivity in semiconductor lasers using gain and spontaneous emission measurements

W. Fang, M. Hattendorf, S. L. Chuang, J. Minch, C. S. Chang, C. G. Bethea, and Y. K. Chen

Appl. Phys. Lett. 70, 796 (1997); http://dx.doi.org/10.1063/1.118225 (3 pages) | Cited 10 times

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A consistent method to characterize the temperature dependence of bulk InGaAsP semiconductor laser diodes is presented. Independent measurements of the gain and spontaneous emission spectra are conducted, and the spectra are calibrated using their fundamental relationship. This procedure will provide a unique approach to extract precise values for laser diode parameters such as quasi-Fermi level separation, peak modal gain, and total loss. The radiative and nonradiative current densities can then be calculated as a function of temperature and injection current. By comparing the measured data with a theoretical model, the carrier density is calculated. Important phenomena contributing to the strong temperature dependence of long-wavelength bulk InGaAsP/InP lasers are highlighted. © 1997 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Recycling of guided mode light emission in planar microcavity light emitting diodes

H. De Neve, J. Blondelle, P. Van Daele, P. Demeester, R. Baets, and G. Borghs

Appl. Phys. Lett. 70, 799 (1997); http://dx.doi.org/10.1063/1.118226 (3 pages) | Cited 58 times

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Results are presented on planar microcavity light emitting diodes with different device diameters. A record external quantum efficiency of 20% is achieved for a 1.5 mm light emitting diode. The strong dependence of the quantum efficiency on current density and device size are compared with theoretical results. A good correspondence is obtained when spectral broadening and photon recycling are taken into account. © 1997 American Institute of Physics.
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85.60.Jb Light-emitting devices
78.66.Fd III-V semiconductors
42.55.Sa Microcavity and microdisk lasers

GaInAsSb/AlGaAsSb multiple-quantum-well diode lasers grown by organometallic vapor phase epitaxy

C. A. Wang and H. K. Choi

Appl. Phys. Lett. 70, 802 (1997); http://dx.doi.org/10.1063/1.118227 (3 pages) | Cited 12 times

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A GaInAsSb/AlGaAsSb multiple-quantum-well diode laser structure consisting of Al0.6Ga0.4As0.05Sb0.95 cladding layers, Al0.3Ga0.7As0.02Sb0.98 confining layers, and four 15-nm-thick Ga0.87In0.13As0.12Sb0.88 quantum wells with 20-nm-thick Al0.3Ga0.7As0.02Sb0.98 barrier layers was grown by organometallic vapor phase epitaxy. These lasers, emitting at 2.1 μm, have exhibited pulsed threshold current densities as low as 1.2 kA/cm2. © 1997 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
78.66.Fd III-V semiconductors
81.15.Kk Vapor phase epitaxy; growth from vapor phase

A study on specific optic impedance of materials

S. Mohanan, V. K. Vaidyan, and K. V. Kurian

Appl. Phys. Lett. 70, 805 (1997); http://dx.doi.org/10.1063/1.118228 (3 pages) | Cited 1 time

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The optic impedance Z of a medium for the propagation of electromagnetic waves is deduced from the definition of wave impedance. A new optical parameter Zo called “specific optic impedance” is defined. The temperature dependence of Zo is examined and an exponential relationship between specific optic impedances at two different temperatures has been derived. The validity of the new relationship is established using the published data on ethyl acetate, cyclohexane, benzene, and a binary mixture of polyvinyl pyrrolidone in N,N-dimethyl formamide solutions from the literature. © 1997 American Institute of Physics.
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42.25.Bs Wave propagation, transmission and absorption
42.70.Jk Polymers and organics

Severe gain suppression due to dynamic carrier heating in quantum well lasers

Matt Grupen and Karl Hess

Appl. Phys. Lett. 70, 808 (1997); http://dx.doi.org/10.1063/1.118229 (3 pages) | Cited 13 times

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Comparing the results of the quantum well laser diode simulator Minilase-II with modulation responses measured at the University of California, Santa Barbara, we show that electron and polar optical phonons are rapidly heated above equilibrium in conventional injection lasers. This heating essentially follows and counteracts the modulation of the carrier density, leading to degradation of the dynamic laser response even for relatively small changes in carrier temperature. With this in mind, we speculate about the use of tunneling injection to avoid the hot quantum carrier effects intrinsic to conventional injection lasers. © 1997 American Institute of Physics.  
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42.55.Px Semiconductor lasers; laser diodes
42.60.Fc Modulation, tuning, and mode locking
85.60.Bt Optoelectronic device characterization, design, and modeling

Stimulated emission at 300 K from photopumped GaN grown by plasma-assisted molecular beam epitaxy with an inductively coupled plasma source

O. Gluschenkov, J. M. Myoung, K. H. Shim, K. Kim, Z. G. Figen, J. Gao, and J. G. Eden

Appl. Phys. Lett. 70, 811 (1997); http://dx.doi.org/10.1063/1.118230 (3 pages) | Cited 7 times

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GaN epilayers have been grown on basal plane (0001) sapphire by plasma-assisted molecular beam epitaxy (MBE) with a novel, inductively coupled nitrogen plasma source. Films grown at 700 °C generate stimulated emission at 300 K when optically pumped in vertical geometry with ∼3.5 eV (λ = 355 nm) photons. The extrapolated pump power threshold is ∼3.6 MW cm−2 which corresponds to an absorbed value of 700 kW cm−2 and a peak carrier number density of ∼ 4×1019 cm−3. © 1997 American Institute of Physics.
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78.45.+h Stimulated emission
42.55.Px Semiconductor lasers; laser diodes
52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition

Exciton spectral splitting near room temperature from high contrast semiconductor microcavities

L. A. Graham, Q. Deng, D. G. Deppe, and D. L. Huffaker

Appl. Phys. Lett. 70, 814 (1997); http://dx.doi.org/10.1063/1.118231 (3 pages) | Cited 6 times

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Spectral splitting due to the exciton response of a three InGaAs quantum well active region placed in various high contrast semiconductor microcavities is observed near room temperature. The planar microcavities consist of one-wavelength thick cavity spacers surrounded by AlGaAs/GaAs along with high contrast distributed Bragg reflectors formed from AlxOy/GaAs and MgF/ZnSe. Microcavities having different loss rates are characterized over a range of temperatures using reflectance, transmission, and photoluminescence. © 1997 American Institute of Physics.
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42.55.Sa Microcavity and microdisk lasers
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
78.66.Fd III-V semiconductors

Measurement of saturation intensities in ion doped solids by transient nonlinear refraction

V. Pilla, P. R. Impinnisi, and T. Catunda

Appl. Phys. Lett. 70, 817 (1997); http://dx.doi.org/10.1063/1.118232 (3 pages) | Cited 11 times

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The transient response of the Z-scan signal ΔT(t) was used to investigate the nonlinearity of ion doped solids. n2 measurements in ruby and alexandrite were performed using an Ar+ laser. We observed that the nonlinearity response time τ decreases with the laser intensity as τ−1 = τ0−1(1+I/Is), where τ0 is the excited state lifetime and Is the transition saturation intensity. So, by measuring the transient response at different laser intensities, we were able to determine not only the nonlinear complex refractive index n2 but also τ0 and Is for Cr+3 in ruby and in the two alexandrite sites. © 1997 American Institute of Physics.
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42.65.An Optical susceptibility, hyperpolarizability
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
42.62.Fi Laser spectroscopy

Image upconversion via unidirectional anti-Stokes generation by reverse-circularly polarized pump beams

X.-W. Xia, S. Wada, K. Akagawa, and H. Tashiro

Appl. Phys. Lett. 70, 820 (1997); http://dx.doi.org/10.1063/1.118233 (3 pages) | Cited 2 times

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Two-dimensional image transfer with frequency upconversion from the pump to the anti-Stokes beam has been realized using polarization coupling in rotational Raman scattering. With two pump beams of counter-rotating circular polarization from a Q-switched Nd:YAG laser, images carried in either pump can be transferred to the anti-Stokes beam through pump-phonon coupling in a hydrogen cell. Image addition has also been demonstrated when different objects are inserted simultaneously in two pump beams. The potential for imaging through scattering media with this technique is discussed. © 1997 American Institute of Physics.
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42.65.Dr Stimulated Raman scattering; CARS
42.65.Es Stimulated Brillouin and Rayleigh scattering
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.30.Va Image forming and processing

Scalability of small-aperture selectively oxidized vertical cavity lasers

Kent D. Choquette, W. W. Chow, G. R. Hadley, H. Q. Hou, and K. M. Geib

Appl. Phys. Lett. 70, 823 (1997); http://dx.doi.org/10.1063/1.118234 (3 pages) | Cited 35 times

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We analyze the threshold properties of small area selectively oxidized vertical cavity lasers. Agreement for threshold gain versus laser size is found using the experimental intrinsic threshold voltage matched with a gain theory, as compared to a two-dimensional optical cavity simulation. Our analysis indicates the increasing threshold current density of small area lasers arises from both increasing threshold gain and the concomitant increasing leakage current. We further show that the optical loss can be reduced for lasers with areas as small as 0.25 μm2 while maintaining sufficient transverse optical confinement by displacing the apertures longitudinally away from the cavity and reducing the oxide thickness. © 1997 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
78.66.Fd III-V semiconductors

High-gain p-i-n infrared photosensors with Bragg reflectors on amorphous silicon–germanium alloy

Jyh-Jier Ho, Y. K. Fang, Kuen-Hsien Wu, and C. S. Tsai

Appl. Phys. Lett. 70, 826 (1997); http://dx.doi.org/10.1063/1.119070 (3 pages) | Cited 5 times

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An amorphous silicon–germanium alloy (α-SiGe:H) infrared photosensor with a Bragg reflector to obtain high optical gain and responsivity is demonstrated. The Bragg reflector containing α-Si:H and α-SiGe:H layers was grown on the top of p-i-n structure with an amorphous silicon/germanium alloy. All of the amorphous silicon and amorphous silicon–germanium layers were deposited by a low-temperature plasma enhanced chemical vapor phase deposition system. The experimental results of the new structures exhibit a much superior performance to that of conventional p-i-n avalanche photosensor structures. That is, the structure with a Bragg reflector shows a significant improvement in optical gain from 80 to 328 under the incident optical power of 1 μW, and the full width at half maximum can be reduced from 250 to 150 nm. © 1997 American Institute of Physics.    
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07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
85.60.Gz Photodetectors (including infrared and CCD detectors)
42.79.Fm Reflectors, beam splitters, and deflectors

Acoustic excitation of the circular Bragg–Fresnel lens in backscattering geometry

A. Souvorov, I. Snigireva, A. Snigirev, E. Aristova, and Ya. Hartman

Appl. Phys. Lett. 70, 829 (1997); http://dx.doi.org/10.1063/1.118240 (3 pages) | Cited 1 time

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An increment of the x-ray flux in crystal Bragg–Fresnel lens (BFL) focus in backscattering geometry obtained by means of acoustic excitation of the BFL crystal substrate has been investigated. The dependence of the x ray’s total reflected power versus ultrasound parameters has been studied in a low frequency range (10–50 MHz). The proposed technique allows an increase in the flux in a BFL focus by a factor of 2 which almost achieves the kinematic limit. © 1997 American Institute of Physics.
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07.85.Fv X- and γ-ray sources, mirrors, gratings, and detectors
78.70.Ck X-ray scattering
42.79.Ci Filters, zone plates, and polarizers
42.79.Jq Acousto-optical devices

Pencil-like mm-size electron beams produced with linear inductive voltage adders

M. G. Mazarakis, J. W. Poukey, D. C. Rovang, J. E. Maenchen, S. R. Cordova, P. R. Menge, R. Pepping, L. Bennett, K. Mikkelson, D. L. Smith, J. Halbleib, W. A. Stygar, and D. R. Welch

Appl. Phys. Lett. 70, 832 (1997); http://dx.doi.org/10.1063/1.118217 (3 pages) | Cited 11 times

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We present the design, analysis, and results of the high brightness electron beam experiments currently under investigation at Sandia National Laboratories. The anticipated beam parameters are the following: energy 12 MeV, current 35–40 kA, rms radius 0.5 mm, and pulse duration 40 ns full width at half-maximum. The accelerator is SABRE, a pulsed linear inductive voltage adder modified to higher impedance, and the electron source is a magnetically immersed foilless electron diode. 20–30 T solenoidal magnets are required to insulate the diode and contain the beam to its extremely small-sized (1 mm) envelope. These experiments are designed to push the technology to produce the highest possible electron current in a submillimeter radius beam. Design, numerical simulations, and experimental results are presented. © 1997 American Institute of Physics.
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52.75.Di Ion and plasma propulsion
41.75.Fr Electron and positron beams

Transport of argon ions in an inductively coupled high-density plasma reactor

N. Sadeghi, M. van de Grift, D. Vender, G. M. W. Kroesen, and F. J. de Hoog

Appl. Phys. Lett. 70, 835 (1997); http://dx.doi.org/10.1063/1.118218 (3 pages) | Cited 27 times

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The first direct observation of the velocity distribution of the metastable Ar+∗(2G9/2) ions in the presheath of an inductively coupled plasma has been achieved by using the Doppler shifted laser induced fluorescence technique. Drift of the ions along the electric field in the presheath is observed and distribution functions of the velocity in both parallel and perpendicular directions, relative to the E field, are deduced at 5 and 40 mTorr. Present results show that in high density plasmas the velocity distribution of the metastable ions is directly related to that of the ground state argon ions. Neutral gas temperature of around 600 K is also measured from the absorption profile of a diode laser beam, set on one of the 772.4 nm argon lines. © 1997 American Institute of Physics.
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52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition

X-ray diffraction study of alternating nanocrystalline silicon/amorphous silicon multilayers

X. L. Wu, S. Tong, X. N. Liu, X. M. Bao, S. S. Jiang, D. Feng, and G. G. Siu

Appl. Phys. Lett. 70, 838 (1997); http://dx.doi.org/10.1063/1.118219 (3 pages) | Cited 15 times

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Structural properties of alternating nanocrystalline silicon/amorphous silicon multilayers with visible light emission at room temperature were examined by means of x-ray diffraction. According to the linewidths and intensities of the diffraction peaks in the low- and high-angle ranges, we have determined the effective interface thickness, the mean crystallite sizes, and the internal strains, which are closely related to the photoluminescence in this material. In addition, the existence of the voids or holes was also observed, indicating that the improved electrical properties of this kind of hydrogenated nanocrystalline materials are due to the inhomogeneous structure of the material. © 1997 American Institute of Physics.
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61.05.cm X-ray reflectometry (surfaces, interfaces, films)
68.35.Ct Interface structure and roughness
61.46.-w Structure of nanoscale materials
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties

Abrupt discontinuous relationships between supercooling and melt overheating

H. Y. Tong and F. G. Shi

Appl. Phys. Lett. 70, 841 (1997); http://dx.doi.org/10.1063/1.118220 (3 pages) | Cited 1 time

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The dependence of the degree of supercooling (ΔT−) of melts preceding the onset of solidification on the level of melt overheating (ΔT+)above the equilibrium liquidus or melting temperature, is investigated on Sn and SnPb. We demonstrate the dependence of ΔT− on ΔT+ can be either abrupt or continuous, depending on the length of holding time. In particular, the dependence is bounded by two discontinuous limits, and the known continuous linear relationship between ΔT− and ΔT+ is only a special possibility. Our observations can be tentatively linked to the transient structural evolution of melts, and are probably general, occurring also for element Bi and SnSb. Our results may have important consequences for any thermal modeling of electronics manufacturing involving soldering operations. © 1997 American Institute of Physics.
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64.70.D- Solid-liquid transitions
64.60.Q- Nucleation
81.20.Vj Joining; welding

Improved atomic force microscopy resolution using an electric double layer

I. Yu. Sokolov, G. S. Henderson, F. J. Wicks, and G. A. Ozin

Appl. Phys. Lett. 70, 844 (1997); http://dx.doi.org/10.1063/1.118221 (3 pages) | Cited 14 times

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High resolution (“atomic”) images of clinochlore and muscovite have been obtained in aqueous solution by inducing an electric double layer between the atomic force microscope tip and the sample surface. The electric double layer is created by the addition of a surfactant to water and greatly improves image resolution. A theoretical model is proposed to explain the improved resolution. © 1997 American Institute of Physics.
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07.79.Lh Atomic force microscopes
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

The characteristics of high-resistance layers produced in n-GaAs using MeV-nitrogen implantation for three-dimensional structuring

J. Miao, I. M. Tiginyanu, H. L. Hartnagel, G. Irmer, J. Monecke, and B. L. Weiss

Appl. Phys. Lett. 70, 847 (1997); http://dx.doi.org/10.1063/1.118222 (3 pages) | Cited 11 times

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The radiation damage introduced in n-GaAs by 4-MeV N+ implantation at a dose of 1×1015 cm−2 has been analyzed using micro-Raman spectroscopy. Implantation followed by annealing at 600 °C was found to produce a strongly compensated near-surface layer possessing a high crystalline quality. At the same time a pronounced disorder was found underneath the high-resistance layer which enables the fabrication of 2.5-μm thick free-standing membranes using selective electrochemical etching techniques.© 1997 American Institute of Physics.
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61.80.Jh Ion radiation effects
78.30.Fs III-V and II-VI semiconductors
85.40.Ry Impurity doping, diffusion and ion implantation technology
81.05.Ea III-V semiconductors

A room-temperature silicon single-electron metal–oxide–semiconductor memory with nanoscale floating-gate and ultranarrow channel

Lingjie Guo, Effendi Leobandung, and Stephen Y. Chou

Appl. Phys. Lett. 70, 850 (1997); http://dx.doi.org/10.1063/1.118236 (3 pages) | Cited 40 times

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See Also: Erratum

Show Abstract
We have demonstrated a room-temperature silicon single-electron transistor memory that consists of (i) a narrow channel metal-oxide–semiconductor field-effect transistor with a width (∼10 nm) smaller than the Debye screening length of single electron; and (ii) a nanoscale polysilicon dot (∼7×7 nm) as the floating gate embedded between the channel and the control gate. We have observed that storing one electron on the floating gate can significantly screen the channel from the potential on the control gate, leading to a discrete shift in the threshold voltage, a staircase relationship between the charging voltage and the threshold shift, and a self-limiting charging process. © 1997 American Institute of Physics.
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85.35.Gv Single electron devices
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
73.23.Hk Coulomb blockade; single-electron tunneling

Subpicosecond switch-off and switch-on of a semiconductor laser due to transient hot carrier effects

M. Elsässer, S. G. Hense, and M. Wegener

Appl. Phys. Lett. 70, 853 (1997); http://dx.doi.org/10.1063/1.118223 (3 pages) | Cited 17 times

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Recently it has been shown that perturbation of an already operating semiconductor laser with an additional pump pulse may lead to an unusual ultrafast switch-off. This effect is due to transient carrier heating. Subsequent carrier cooling allows for switch-on after about two picoseconds. In vertical cavity lasers containing only a few quantum wells as the active medium, the recovery, however, is limited by the comparatively low gain in the cavity. Here we demonstrate experimentally that both switch-off and switch-on can exhibit subpicosecond time constants if a bulk semiconductor is used as the active medium. © 1997 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
78.47.-p Spectroscopy of solid state dynamics

Room temperature electro-optic effect in CdHgTe multiple quantum well heterostructures at 1.5 μm

Guido Mula, N. T. Pelekanos, P. Gentile, N. Magnea, and J. L. Pautrat

Appl. Phys. Lett. 70, 856 (1997); http://dx.doi.org/10.1063/1.118297 (3 pages)

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We present a study of the room temperature electromodulation properties of CdHgTe heterostructures as a base component for a photorefractive device operating at 1.5 μm. We reach absorption modulation as high as 200%, in the near-gap transparent region of the spectrum, by application of a reverse bias of the order of 100 kV/cm. We observe the transition from the Franz–Keldysh effect in 200 Å wide wells to the quantum confined Stark effect in 90 Å wells. The calculated diffraction efficiency in a suitable photorefractive device would be of the order of 8×10−4 in both cases. © 1997 American Institute of Physics.
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78.20.Jq Electro-optical effects
78.66.Hf II-VI semiconductors
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials

A high strain two-stack two-color quantum well infrared photodetector

M. Z. Tidrow, J. C. Chiang, Sheng S. Li, and K. Bacher

Appl. Phys. Lett. 70, 859 (1997); http://dx.doi.org/10.1063/1.118298 (3 pages) | Cited 27 times

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A high strain two-stack, two-color, InGaAs/AlGaAs and AlGaAs/GaAs quantum well infrared photodetector for midwavelength infrared (MWIR) and long wavelength infrared (LWIR) detection has been demonstrated. Each stack is designed to have detection in one of the two atmospheric windows, 3–5 μm and 8–12 μm, respectively. The MWIR stack has employed 35% of indium in the InGaAs well, which not only achieved peak wavelength at 4.3 μm, but also obtained very high peak responsivity of Rp = 0.65 A/W, using 45° light coupling. Normal incidence without grating coupling also has high responsivity with 40%–50% in the MWIR stack and 35%–45% in the LWIR stack, respectively, compared with the 45° incidence. Despite the large in-plane compressive strain induced by the high indium concentration, the device is highly uniform and has very low dark current in the MWIR stack. The background limited temperature is 125 K for the MWIR stack with a cutoff wavelength λc = 4.6 μm, and is 70 K for the LWIR stack with λc = 10 μm. © 1997 American Institute of Physics.
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85.60.Gz Photodetectors (including infrared and CCD detectors)
78.66.Fd III-V semiconductors
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors

Hole perpendicular transport in GaAs–AlGaAs superlattices

Bing Dong and X. L. Lei

Appl. Phys. Lett. 70, 862 (1997); http://dx.doi.org/10.1063/1.118299 (3 pages)

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We investigate the hole perpendicular transport properties in semiconductor superlattices (SLs) by using the extended Lei–Ting balance equation theory for an arbitrary energy band including hole-impurity, hole-polar-optic-phonon, and hole-nonpolar-optic-phonon scatterings. Effects of heavy-hole–light-hole mixing are taken into account by means of the approximate dispersion relation suggested by O. E. Raichev [Phys. Rev. B 50, 5382 (1994)]. Numerical calculations show that the complex hole energy spectrum causes a breakdown of the negative differential conductance for the hot-hole perpendicular transport in SLs in contrast with the results corresponding to a simplified electronlike energy spectrum. © 1997 American Institute of Physics.
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73.50.Bk General theory, scattering mechanisms
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

Epitaxial regrowth of Ge films on (001) GaAs by in situ thermal pulse annealing of evaporated amorphous germanium

K. M. Lui, K. P. Chik, and J. B. Xu

Appl. Phys. Lett. 70, 865 (1997); http://dx.doi.org/10.1063/1.119071 (3 pages) | Cited 4 times

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Germanium thin films have been epitaxially regrown on (001) GaAs by in situ thermal pulse annealing of evaporated amorphous germanium under <102 Watt/cm2 broad-band irradiation in high vacuum. Epitaxial regrowth was found to occur only when the duration of the thermal pulse (te) was greater than a critical value tc (≃3.20 s). The crystal quality of the resultant film was examined by high resolution x-ray diffraction technique (HRXRD) and grazing-incidence x-ray diffraction technique (GIXRD). All rocking curves were found to have a full width at half-maximum of about 0.02°. Both HRXRD and GIXRD confirmed the Ge overlayer was grown epitaxially as well as pseudomorphically on the substrate. Scanning electron microscopy and atomic force microscopy revealed the very different surface morphologies resulting from different te. For te<tc, columnar germanium grains with a four-fold symmetry and a high uniformity in size were found, while for te ≥ tc, epitaxial regrowth was observed. It is suggested that epitaxial regrowth takes place via a temporary formation of liquid phase Ge. © 1997 American Institute of Physics.
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68.55.-a Thin film structure and morphology
81.15.Np Solid phase epitaxy; growth from solid phases
81.05.Cy Elemental semiconductors
61.05.cm X-ray reflectometry (surfaces, interfaces, films)
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