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18 Dec 1995

Volume 67, Issue 25, pp. 3673-3818

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Low‐pressure organometallic chemical vapor deposition of quantum wires on V‐grooved substrates

A. Gustafsson, F. Reinhardt, G. Biasiol, and E. Kapon

Appl. Phys. Lett. 67, 3673 (1995); http://dx.doi.org/10.1063/1.114923 (3 pages) | Cited 58 times

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The structure of GaAs/AlGaAs quantum wires (QWRs) and vertical quantum wells (VQWs) grown by low‐pressure organometallic chemical vapor deposition was investigated by conventional and high resolution transmission electron microscopy, and by low‐temperature cathodoluminescence. The lower wire boundaries show a much smaller radius of curvature, as compared with atmospheric pressure growth of similar structures, and the upper boundaries show distinct faceting. More abrupt interfaces are obtained due to the kinetically limited growth, with measured interface grading as small as one or two monolayers. The VQW structures formed in the AlGaAs barrier exhibit several branches related to the faceting of the QWR boundaries. These characteristics of the low‐pressure nonplanar growth should allow the fabrication of quasi‐one‐dimensional QWRs with size and shape controlled on the monolayer level. © 1995 American Institute of Physics.
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68.37.Hk Scanning electron microscopy (SEM) (including EBIC)
68.37.Lp Transmission electron microscopy (TEM)
81.15.Kk Vapor phase epitaxy; growth from vapor phase
78.60.Hk Cathodoluminescence, ionoluminescence
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

Growth of 1.3 μm InAsP/InGaAsP laser structures by gas source molecular beam epitaxy

P. Thiagarajan, A. A. Bernussi, H. Temkin, G. Y. Robinson, A. M. Sergent, and R. A. Logan

Appl. Phys. Lett. 67, 3676 (1995); http://dx.doi.org/10.1063/1.114924 (3 pages) | Cited 13 times

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The optimization of growth conditions for high quality 1.3 μm InAsP/InGaAsP laser structures by gas source molecular beam epitaxy is reported. Measurements of photoluminescence intensity and threshold currents of highly strained InAsP/InGaAsP multiple quantum well (MQW) lasers indicate an optimum growth temperature substantially lower than that for conventional 1.3 μm InGaAsP quaternary lasers. Broad‐area laser structures grown under the optimum conditions exhibited threshold current densities as low as 400 A/cm2. Buried heterostructures with uncoated facets exhibited threshold currents as low as 5.0 mA and internal losses of 8.0 cm−1. © 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
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Intracavity injection lasing in a hybrid neodymium laser

Li Yan and Lei Ding

Appl. Phys. Lett. 67, 3679 (1995); http://dx.doi.org/10.1063/1.114925 (3 pages) | Cited 5 times

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A hybrid neodymium (Nd) laser that contains Nd:YLF and Nd:phosphate glass media in a single cavity was demonstrated. In a wide range of gain conditions, the original lasing spectrum of Nd:glass can be suppressed and the hybrid laser spectrum was ‘‘locked’’ to that of Nd:YLF, even when Nd:YLF was pumped below its threshold. © 1995 American Institute of Physics.
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42.55.Rz Doped-insulator lasers and other solid state lasers
42.60.-v Laser optical systems: design and operation

Degradation of the second order optical nonlinearity in cubic media by straight dislocations

D. J. Bottomley

Appl. Phys. Lett. 67, 3682 (1995); http://dx.doi.org/10.1063/1.114926 (3 pages) | Cited 4 times

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The influence of straight dislocations on the second order nonlinear optical susceptibility χ(2) of cubic noncentrosymmetric media has been modeled. The resulting degradation of χ(2) has been evaluated for screw and edge dislocations in GaAs. It is found that single screw and edge dislocations reduce the χ(2) of GaAs by a third and ∼60%, respectively. This implies that second order nonlinear optical effects are very sensitive to misfit dislocation generation in epitaxially grown noncentrosymmetric media and that dislocation‐free epilayers are required to realize the optimum χ(2). © 1995 American Institute of Physics.
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42.65.-k Nonlinear optics
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
61.72.Lk Linear defects: dislocations, disclinations
78.66.Fd III-V semiconductors

High efficiency surface emitting lasers using blazed grating outcouplers

Mats Hagberg, Niklas Eriksson, and Anders Larsson

Appl. Phys. Lett. 67, 3685 (1995); http://dx.doi.org/10.1063/1.114927 (3 pages) | Cited 11 times

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Grating coupled surface emitting lasers with rectangular as well as blazed grating outcouplers were investigated. Horizontal cavity InGaAs/AlGaAs laser oscillators, with two rectangular first order surface gratings as feedback elements, were integrated with single detuned rectangular or blazed second order gratings as surface output couplers, using electron beam lithography and chemically assisted ion beam etching. Superior differential quantum and surface emission efficiencies of 56% and 84%, respectively, were measured for lasers with optimized blazed output couplers. © 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

Temperature dependence of terahertz pulses produced by difference‐ frequency mixing in InSb

S. C. Howells and L. A. Schlie

Appl. Phys. Lett. 67, 3688 (1995); http://dx.doi.org/10.1063/1.114928 (3 pages) | Cited 13 times

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Terahertz radiation emitted from (111) InSb illuminated with focused 1.4 μm laser pulses is due to both difference‐frequency mixing and depletion field driven current. By rotating an undoped (111) InSb sample at a temperature of 80 K about its surface normal, we were able to separate the relative contribution of the azimuthally dependent difference‐frequency mixing (DFM) signal from the total terahertz wave form. Contrary to expectations, it was found that the azimuthally dependent spectrum appears nearly identical to the azimuthally independent spectrum. From this, it is concluded that the spectrum of the current surge signal blue shifts as the pump is focused. Also, a strong similarity exists between the temperature dependence of the DFM and current surge signals. © 1995 American Institute of Physics.
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42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials

Optimizing power extraction in stretched‐pulse fiber ring lasers

K. Tamura and M. Nakazawa

Appl. Phys. Lett. 67, 3691 (1995); http://dx.doi.org/10.1063/1.115351 (3 pages) | Cited 11 times

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A variable output coupling scheme is described for a stretched‐pulse polarization additive pulse mode‐locked (APM) fiber ring laser. The scheme allows the coupling percentage to be changed while the laser is running and allows for the maximum possible power extraction before cavity losses inhibit mode‐locked operation. We describe how the nonlinear pulse dynamics change to compensate the change in cavity loss. Compared to high power output coupling schemes that use the APM rejection port, this method provides cleaner output pulses at comparable output powers. Pulse energies of 0.39 nJ are obtained at 48% output coupling in a diode‐pumped system. 88 fs pulses with time‐bandwidth products of 0.49 are obtained after output chirp compensation using a silicon prism pair. © 1995 American Institute of Physics.
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42.55.Wd Fiber lasers
42.60.Fc Modulation, tuning, and mode locking
42.65.Re Ultrafast processes; optical pulse generation and pulse compression

An annealing study of luminescent amorphous silicon‐rich silicon oxynitride thin films

B. H. Augustine, Y. Z. Hu, E. A. Irene, and L. E. McNeil

Appl. Phys. Lett. 67, 3694 (1995); http://dx.doi.org/10.1063/1.115352 (3 pages) | Cited 13 times

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We report the effect of the rapid thermal annealing (RTA) of amorphous silicon oxynitride (a‐SiOxNy:H) thin films on the room‐temperature photoluminescence (PL). Samples were prepared by plasma enhanced chemical vapor deposition. The PL intensity increased by one order‐of‐magnitude after annealing for 20 min at 800 °C compared to that of the as‐deposited sample. We have followed the changes in the chemical microstructure of the materials by in situ real‐time ellipsometry, and suggest that the annealing is characterized by two distinct mechanisms. The first is that hydrogen effusion from clustered hydrogen and/or =N–H bond breaking occurs in the first 5 min resulting in increasing dangling bond density and no increase in the PL intensity. The second occurs after longer annealing times due to local reconstruction of Si–O and Si–N bonds, rather than diffusional rearrangement of the atomic species. This results in a more dense material with a higher refractive index, fewer nonradiative recombination centers, and more efficient PL. A model is presented to describe both the radiative and nonradiative recombination processes. © 1995 American Institute of Physics.
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78.66.Jg Amorphous semiconductors; glasses
81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization

Calibrated intensity noise measurements in microcavity laser diodes

E. Goobar, J. W. Scott, B. Thibeault, G. Robinson, Y. Akulova, and L. A. Coldren

Appl. Phys. Lett. 67, 3697 (1995); http://dx.doi.org/10.1063/1.115353 (3 pages) | Cited 17 times

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Calibrated intensity noise measurements of microcavity lasers diodes are presented. Partition noise due to polarization degeneracy is found to render excess noise that destroys squeezing. The measurements indicate that it may be necessary to introduce polarization control to realize sub‐shot‐noise levels in microcavity laser diodes. © 1995 American Institute of Physics.
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42.50.Lc Quantum fluctuations, quantum noise, and quantum jumps
42.55.Px Semiconductor lasers; laser diodes
42.60.Mi Dynamical laser instabilities; noisy laser behavior

Mid‐wave infrared diode lasers based on GaInSb/InAs and InAs/AlSb superlattices

D. H. Chow, R. H. Miles, T. C. Hasenberg, A. R. Kost, Y.‐H. Zhang, H. L. Dunlap, and L. West

Appl. Phys. Lett. 67, 3700 (1995); http://dx.doi.org/10.1063/1.115354 (3 pages) | Cited 49 times

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We report the characterization of a set of broad‐area semiconductor diode lasers with mid‐wave infrared (3–5 μm) emission wavelengths. The active region of each laser structure is a 5‐ or 6‐period multiple quantum well (MQW) with Ga0.75In0.25As0.22Sb0.78 barriers and type‐II (broken‐gap) Ga0.75In0.25Sb/InAs superlattice wells. The cladding layers of each laser structure are n‐ and p‐type InAs/AlSb (24 Å /24 Å) superlattices grown lattice‐matched to a GaSb substrate. By tailoring constituent layer thicknesses in the Ga0.75In0.25Sb/InAs superlattice wells, laser emission wavelengths ranging from 3.28 μm (maximum operating temperature=170 K) to 3.90 μm (maximum operating temperature=84 K) are obtained. © 1995 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
85.60.Jb Light-emitting devices

Two‐photon pumped cavity lasing in novel dye doped bulk matrix rods

Guang S. He, Chan F. Zhao, Jayant D. Bhawalkar, and Paras N. Prasad

Appl. Phys. Lett. 67, 3703 (1995); http://dx.doi.org/10.1063/1.115355 (3 pages) | Cited 80 times

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Trans‐4‐[p‐(N‐ethyl‐N‐hydroxyethylamino)styryl]‐N‐methylpyridi that possesses a much greater two‐photon absorption cross section and much stronger upconversion fluorescence emission than common organic dyes (such as rhodamine), when excited with near infrared laser radiation. Utilizing ASPT doped bulk polymer rods, two‐photon pumped frequency upconverted cavity lasing has been accomplished using a Q‐switched Nd:YAG laser as the pump source. The wavelength and pulse duration were ∼600 nm and 3–6 ns, respectively, for the cavity lasing; whereas the corresponding values for pump pulses were 1.06 μm and ∼10 ns, respectively. For a 7 mm long sample rod with a dopant concentration d0=8×10−3 M/L, the conversion efficiency from the absorbed pump energy to the cavity lasing output was ∼3.5% at a pump energy level of 1.3 mJ. The lasing lifetime, in terms of pulse numbers, was more than 4×104 pulses at 2 Hz repetition rate and room temperature. © 1995 American Institute of Physics.
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42.55.Mv Dye lasers
42.70.Hj Laser materials

Effects of nonuniform photon distribution on high speed response in semiconductor distributed feedback lasers

J. Feng, T. R. Chen, and A. Yariv

Appl. Phys. Lett. 67, 3706 (1995); http://dx.doi.org/10.1063/1.115356 (3 pages) | Cited 3 times

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The high speed performance of distributed feedback (DFB) lasers, with nonuniform longitudinal photon density distributions, has been analyzed. It was found that the relaxation resonance frequency and damping rate of the lasers depended on the distribution of traveling electric fields in the lasers. A two section DFB laser was used to demonstrate the effects of spatial hole burning on the high speed response of the DFB laser. By adjusting the photon density distribution in the laser through nonuniform current injection, the resonance frequency and damping rate of the two section DFB laser can be changed even if the output optical power is kept constant. © 1995 American Institute of Physics.  
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42.55.Px Semiconductor lasers; laser diodes
42.60.Fc Modulation, tuning, and mode locking

Ultrafast polarization‐discriminating Mach‐Zehnder all‐optical switch

K. Tajima, S. Nakamura, and Y. Sugimoto

Appl. Phys. Lett. 67, 3709 (1995); http://dx.doi.org/10.1063/1.115357 (3 pages) | Cited 40 times

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We propose a polarization‐discriminating Mach‐Zehnder (PDMZ) all‐optical switch. The switching speed of this PDMZ all‐optical switch is not limited by the slow relaxation time of highly efficient incoherent nonlinearities. We demonstrate a squarelike modulation characteristic, which is necessary in most switching applications, at a switching speed (on‐off time) of 40 ps. We also demonstrate ultrafast switching at a detector limited speed of ∼8 ps. © 1995 American Institute of Physics.
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42.65.Pc Optical bistability, multistability, and switching, including local field effects
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.79.Sz Optical communication systems, multiplexers, and demultiplexers
42.79.Ta Optical computers, logic elements, interconnects, switches; neural networks

Limitations of diffusion approximation in describing femtosecond laser transillumination of highly scattering media of biological significance

Theodore G. Papazoglou, W. Q. Liu, Alex Vasiliou, Ralf Grassmel, Emmanuel Papagiannakis, and Costas Fotakis

Appl. Phys. Lett. 67, 3712 (1995); http://dx.doi.org/10.1063/1.115358 (3 pages) | Cited 1 time

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Ultrafast laser pulses transmitted through highly scattering media have been detected by a streak camera. Experimental data, showing the temporal spread of the ultrafast pulse during the transmission through highly scattering media with various optical discontinuities, have been approximated using the diffusion theory. This analysis explicitly shows how the overall optical parameters of the sample (μa,μs′) are influenced by the presence of the discontinuities and proposes the full width at half‐maximum as an experimental index of the transition between ballistic and diffusive photon transport. © 1995 American Institute of Physics.
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42.25.Bs Wave propagation, transmission and absorption
42.30.-d Imaging and optical processing
42.62.Be Biological and medical applications

Distributed Bragg reflection in integrated waveguides of polymethylmethacrylate

N. Mukherjee, B. J. Eapen, D. M. Keicher, S. Q. Luong, and A. Mukherjee

Appl. Phys. Lett. 67, 3715 (1995); http://dx.doi.org/10.1063/1.115359 (3 pages) | Cited 10 times

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Distributed Bragg reflection from integrated polymethylmethacrylate waveguides fabricated on corrugated spin‐on‐glass substrate is reported. Utilizing third‐order Bragg resonance, a maximum reflection of 92% from the grating filter is measured at a wavelength of 423.6 nm. A maximum bandwidth of the Bragg reflection is found to be ∼0.5 nm for a 6 mm long filter. The broad bandwidth and the significant transmission loss (∼90%) away from resonance are believed to be related to the radiation coupling by the grating. It is shown that the radiation loss can be minimized without sacrificing high reflectivity by limiting the waveguide length to 0.5 mm, the saturation length of the Bragg reflector. © 1995 American Institute of Physics.
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42.82.Et Waveguides, couplers, and arrays

Thin‐oxide charging damage to microelectronic test structures in an electron‐cyclotron‐resonance plasma

J. B. Friedmann, J. L. Shohet, J. P. McVittie, and S. M. Ma

Appl. Phys. Lett. 67, 3718 (1995); http://dx.doi.org/10.1063/1.115360 (3 pages) | Cited 3 times

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Processing yields in electron‐cyclotron‐resonance (ECR) and other high‐density plasma sources will be increasingly limited by plasma‐induced damage. This work investigates the effects of plasma nonuniformities on charging damage to polysilicon‐gate MOS capacitor test structures exposed to O2 ECR plasmas. The nonuniformities were produced by independently biasing electrodes located above the wafer. The damage was characterized with ramp‐voltage breakdown measurements. Comparison of calculated profiles of the potential difference across the gate‐oxide layers of the MOS capacitors with whole wafer maps of the breakdown voltage measurements shows that maximum damage occurs where the oxide potential difference is largest but only in the presence of plasma nonuniformities. © 1995 American Institute of Physics.
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52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition
73.50.Mx High-frequency effects; plasma effects
85.40.Hp Lithography, masks and pattern transfer

Surface structure of homoepitaxial diamond (001) films, a scanning tunneling microscopy study

Yalei Kuang, Yafei Wang, Naeson Lee, Andrzej Badzian, Teresa Badzian, and Tien T. Tsong

Appl. Phys. Lett. 67, 3721 (1995); http://dx.doi.org/10.1063/1.115361 (3 pages) | Cited 22 times

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The surface structures of homoepitaxial diamond (001) films have been studied by using scanning tunneling microscopy. Boron‐doped films were grown on natural diamond substrates. Images showed a dimer‐type 2×1 reconstruction with well‐resolved dimers. The surface consists of alternating terraces of 2×1 and 1×2 dimerization which are separated by single‐layer steps with inequivalent step edges along 〈110〉 directions. Double‐layer steps running parallel to dimer rows of the upper terraces were observed locally. We have also observed local 3×1 configurations, antiphase boundaries, and dimer vacancies, etc. © 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
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.55.-a Thin film structure and morphology

High quality CeO2 film grown on Si(111) substrate by using low energy dual ion beam deposition technology

Dading Huang, Fuguang Qin, Zhengyu Yao, Zhizhang Ren, Lanying Lin, Weibin Gao, and Qingyu Ren

Appl. Phys. Lett. 67, 3724 (1995); http://dx.doi.org/10.1063/1.115362 (2 pages) | Cited 22 times

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By using the mass‐analyzed low energy dual ion beam deposition technique, a high quality epitaxial, insulating cerium dioxide thin film with a thickness of about 2000 Å has been grown on a silicon (111) substrate. The component species, cerium and oxygen, are homogeneous in depth, and have the correct stoichiometry for CeO2. X‐ray double‐crystal diffraction shows that the full width at half maximum of the (222) and (111) peaks of the film are less than 23 and 32 s, respectively, confirming that the film is a perfect single crystal. © 1995 American Institute of Physics.
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81.15.-z Methods of deposition of films and coatings; film growth and epitaxy

High intensity femtosecond laser pump‐probing measurements of a Cu surface

Ding Liu and D. R. Alexander

Appl. Phys. Lett. 67, 3726 (1995); http://dx.doi.org/10.1063/1.115363 (3 pages)

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Both the time and pumping power dependences of the reflectivity of a Cu surface were measured. The role of free electrons and the d‐band electrons in the time dependent reflectivity changes are analyzed. Theoretical calculations based on a d‐band transition model have been performed to describe the power dependence of the reflectivity changes. Results suggest that d‐band electron transitions play an important role especially at early times and low pumping intensities. © 1995 American Institute of Physics.
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78.47.-p Spectroscopy of solid state dynamics
78.66.Bz Metals and metallic alloys

Reduction of the C54–TiSi2 phase transformation temperature using refractory metal ion implantation

R. W. Mann, G. L. Miles, T. A. Knotts, D. W. Rakowski, L. A. Clevenger, J. M. E. Harper, F. M. D’Heurle, and C. Cabral

Appl. Phys. Lett. 67, 3729 (1995); http://dx.doi.org/10.1063/1.115364 (3 pages) | Cited 77 times

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We report that the ion implantation of a small dose of Mo into a silicon substrate before the deposition of a thin film of Ti lowers the temperature required to form the commercially important low resistivity C54–TiSi2 phase by 100–150 °C. A lesser improvement is obtained with W implantation. In addition, a sharp reduction in the dependence of C54 formation on the geometrical size of the silicided structure is observed. The enhancement in C54 formation observed with the ion implantation of Mo is not explained by ion mixing of the Ti/Si interface or implant‐induced damage. Rather, it is attributed to an enhanced nucleation of C54–TiSi2 out of the precursor high resistance C49–TiSi2 phase. © 1995 American Institute of Physics.
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68.35.Md Surface thermodynamics, surface energies
68.35.Rh Phase transitions and critical phenomena
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
68.55.Nq Composition and phase identification

Sharpened electron beam deposited tips for high resolution atomic force microscope lithography and imaging

M. Wendel, H. Lorenz, and J. P. Kotthaus

Appl. Phys. Lett. 67, 3732 (1995); http://dx.doi.org/10.1063/1.115365 (3 pages) | Cited 62 times

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We employ the vibrating tip of an atomic force microscope as a lithographic tool to mechanically pattern a thin photoresist layer covering a GaAs–AlGaAs heterostructure. High aspect ratio electron beam deposited tips, additionally sharpened in an oxygen plasma, are used to minimize the dimensions of the fabricated quantum electronic devices. The fabrication parameters of the tips and the sharpening process are investigated. With these ultrasharp tips we are able to produce lines and holes with periods down to 9 nm in photoresist. In addition, the very sharp tips yield substantial improvements in the imaging mode. © 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

Lattice location of rare‐earth ions in LiNbO3

A. Lorenzo, H. Jaffrezic, B. Roux, G. Boulon, and J. García‐Solé

Appl. Phys. Lett. 67, 3735 (1995); http://dx.doi.org/10.1063/1.115366 (3 pages) | Cited 56 times

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The lattice location of three rare‐earth ions (Pr3+, Ho3+, Yb3+) in LiNbO3 is investigated using Rutherford backscattering spectrometry/channeling techniques. All of them are found to occupy the Li+ octahedron but shifted from the Li+ regular position by different amounts (−0.45 Å for Pr3+, −0.38 Å for Ho3+, and −0.3 Å for Yb3+) as previously reported for other rare‐earth ions. The amount of displacement is directly related to the variation of the ionic radius of the rare‐earth ion, oppositely to transition metal ions which are not shifted. A simple model based on electronic configuration is given to account for this behavior. © 1995 American Institute of Physics.
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42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
61.72.up Other materials
71.55.Ht Other nonmetals

Subthreshold slope in polycrystalline silicon thin‐film transistors and effect of the gate oxide on the subthreshold characteristics

C. A. Dimitriadis

Appl. Phys. Lett. 67, 3738 (1995); http://dx.doi.org/10.1063/1.115367 (3 pages)

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A simple expression for the inverse subthreshold slope in polycrystalline silicon thin‐film transistors (TFTs) is derived as a function of the gate voltage and with parameters the trapping states at the grain boundaries, the grain size, and the gate oxide. Comparison with the experimental results verifies the validity of the derived expression. We show that in polysilicon TFTs, even with high trapping states density and small grain size, excellent subthreshold characteristics can be obtained by scaling down the SiO2 thickness to 10 nm. Further improvement in the subthreshold characteristics can be achieved using as gate oxide a Si3N4/SiO2 bilayer of thickness 10 nm which has higher dielectric constant, exhibits good interface properties with polysilicon and serves as a diffusion barrier to avoid penetration effects of impurities through the oxide. © 1995 American Institute of Physics.
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85.30.De Semiconductor-device characterization, design, and modeling
85.30.Tv Field effect devices

Effect of phosphorus composition on the structural quality of GaInP/GaAsP short‐period superlattices

K. L. Whittingham, D. T. Emerson, J. R. Shealy, M. J. Matragrano, and D. G. Ast

Appl. Phys. Lett. 67, 3741 (1995); http://dx.doi.org/10.1063/1.115368 (3 pages) | Cited 3 times

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Short‐period Ga0.51In0.49P/GaAsyP1−y strained superlattices were grown, by organometallic vapor phase epitaxy, with periods around 70 Å and phosphorus compositions from 0.04 to 0.31. Ground state emission as high as 1.73 eV was observed. Model solid theory predictions fit this data well, particularly at lower P compositions. Type II structures were obtained for phosphorus compositions above 0.04. The introduction of phosphorus in the low bandgap regions of these superlattices was found to significantly improve their structural and optical quality. These superlattices provide, in many applications, a viable alternative to the quaternary alloy GaInAsP, which is required for obtaining these bandgaps in Al‐free systems lattice‐matched to GaAs. To our knowledge this is the first report on the growth and modeling of short‐period superlattices using this material system. © 1995 American Institute of Physics.
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81.15.Kk Vapor phase epitaxy; growth from vapor phase
68.55.-a Thin film structure and morphology
78.66.Fd III-V semiconductors

Relationship between surface morphology and strain relaxation during growth of InGaAs strained layers

C. Lavoie, T. Pinnington, E. Nodwell, T. Tiedje, R. S. Goldman, K. L. Kavanagh, and J. L. Hutter

Appl. Phys. Lett. 67, 3744 (1995); http://dx.doi.org/10.1063/1.115369 (3 pages) | Cited 21 times

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The relationship between the surface morphology and strain relaxation is explored in strained InxGa1−xAs layers grown on GaAs by molecular beam epitaxy. In situ light scattering, detected simultaneously along [110] and [110], reveals an asymmetric surface roughening which is consistent with ex situ scanning force microscopy. Transmission electron microscopy shows that strain relaxation by misfit dislocation formation occurs before the surface roughening is detected, for In0.18Ga0.82As films grown at 490 °C. © 1995 American Institute of Physics.
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61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.-a Thin film structure and morphology
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