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21 Mar 1994

Volume 64, Issue 12, pp. 1463-1593

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Thermal quenching properties of Er‐doped GaP

X. Z. Wang and B. W. Wessels

Appl. Phys. Lett. 64, 1537 (1994); http://dx.doi.org/10.1063/1.111884 (3 pages) | Cited 15 times

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The photoluminescent properties of the Er‐doped epitaxial layers of GaP prepared by metalorganic vapor phase epitaxy were studied as a function of temperature. Strong characteristic Er3+ intra‐4f‐shell emission is observed over the temperature range of 12–300 K. The integrated intensity of the 0.805‐eV emission is only weakly temperature dependent, decreasing by a factor of 2 as the temperature increases from 12 to 300 K. The observation of minimal thermal quenching indicates that Er‐doped GaP is a promising material for optical devices emitting at 1.54 μm and operating at room temperature.
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78.55.Cr III-V semiconductors
73.61.Ey III-V semiconductors

Dual‐function semiconducting polymer devices: Light‐emitting and photodetecting diodes

G. Yu, C. Zhang, and A. J. Heeger

Appl. Phys. Lett. 64, 1540 (1994); http://dx.doi.org/10.1063/1.111885 (3 pages) | Cited 138 times

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Thin film devices made with poly[2‐methoxy‐5‐(2′‐ethyl‐hexyloxy)‐1,4‐phenylene vinylene], MEH‐PPV, are known to be efficient light‐emitting diodes. The same devices, under reverse bias, exhibit excellent sensitivity as photodiodes. Thus the polymer tunnel diode is a dual‐function device. For the Ca/MEH‐PPV/ITO (indium/tin oxide) layered structure, the external quantum efficiency for electroluminescence is ≊1% photons/electron (forward bias ≳2.5 V). The same device is sensitive as a photodiode: The dc sensitivity (−10 V, reverse bias) is 9×10−2 A/W (at ∼1‐μW/cm2 input) corresponding to a quantum yield of more than 20% electrons/photon.
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78.55.-m Photoluminescence, properties and materials
78.60.Fi Electroluminescence
73.50.Pz Photoconduction and photovoltaic effects
73.61.Ph Polymers; organic compounds

Amphoteric substitutionality and lattice distortion of Ge in InP

Kin Man Yu, A. J. Moll, W. Walukiewicz, N. Derhacobian, and C. Rossington

Appl. Phys. Lett. 64, 1543 (1994); http://dx.doi.org/10.1063/1.111886 (3 pages) | Cited 6 times

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We have studied the electrical and structural properties of InP implanted with Ge ions (2×1015/cm2). The implantation was performed at both room temperature (RT) and liquid nitrogen temperature (LNT). After annealing at 850 °C for 5 s, both sets of samples exhibited n‐type conductivity. The n‐type activation efficiency in the RT implanted sample was about a factor of 2 higher than that in the LNT sample (15% and 8%, respectively). Extended x‐ray absorption fine structure spectroscopy (EXAFS) shows direct evidence of the amphoteric substitutionality of the Ge atoms in InP for both samples. The ratios of Ge on In sites to Ge on P sites, derived from the EXAFS results, are consistent with the electrical behavior of the samples. The EXAFS results also reveal that the Ge—In and Ge—P bond lengths in the RT sample are very similar to their theoretical values, but are very different from the original In—P bond length. A relaxation in the Ge—In bond is observed in the LNT sample, resulting in a Ge—In bond length very similar to the original In—P bond length.
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72.80.Ey III-V and II-VI semiconductors
61.05.cf X-ray scattering (including small-angle scattering)
61.05.cj X-ray absorption spectroscopy: EXAFS, NEXAFS, XANES, etc.

Strong accumulation of As precipitates in low temperature InGaAs quantum wells grown by molecular beam epitaxy

T. M. Cheng, Albert Chin, C. Y. Chang, M. F. Huang, K. Y. Hsieh, and J. H. Huang

Appl. Phys. Lett. 64, 1546 (1994); http://dx.doi.org/10.1063/1.111861 (3 pages) | Cited 14 times

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Low temperature InGaAs strained quantum wells have been grown by molecular beam epitaxy and annealed at 600–900 °C for 10 min. For an optimized annealing condition, arsenic precipitates can be successfully confined in the InGaAs wells and completely depleted in the GaAs barriers. The strong accumulation of As precipitates shows that the phenomena are not due to the strain effect but may be explained by the difference of interfacial energy between precipitate and matrix. The ability to control the As precipitates into two‐dimensional quantum wells in LT materials has unique applications in a wide variety of devices.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
61.72.J- Point defects and defect clusters
64.75.-g Phase equilibria

Study of mechanism to control electrical properties of AlAs grown using amine‐alane with metalorganic molecular‐beam epitaxy

Kaoru Miyakoshi and Ikuo Suemune

Appl. Phys. Lett. 64, 1549 (1994); http://dx.doi.org/10.1063/1.111862 (3 pages) | Cited 1 time

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A mechanism to control electrical properties of AlAs films grown by metalorganic molecular‐beam epitaxy using trimethylamine‐alane (TMAAl) and tris‐dimethylamino‐arsenic was studied. Electrical properties of AlAs showed a critical dependence on the V/III supply ratio of the precursors. Quadrupole mass spectrometric studies suggested that the main factor to control the electrical properties is the decomposition of trimethylamine in TMAAl on Al surfaces, which is normally stable and does not decompose on GaAs surfaces.
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73.61.Ey III-V semiconductors

Anomalous diffusion of isoelectronic antimony implant induced defects in GaAs‐AlGaAs multiquantum well structures

E. V. K. Rao, Ph. Krauz, H. Thibierge, R. Azoulay, and C. Vieu

Appl. Phys. Lett. 64, 1552 (1994); http://dx.doi.org/10.1063/1.111863 (3 pages)

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We present here evidence on the deep diffusion of isoelectronic Sb implant induced defects in thick GaAs‐AlGaAs multiquantum well structures (MQW) to depths as far as ∼30 times the implant projected range (Rp). This observation has been confirmed by performing low temperature photoluminescence depth scanning measurements and cross‐sectional transmission electron microscopy (XTEM) analysis on room temperature Sb implanted thick MQW samples. An explanation based on the isoelectronic nature of Sb and its substitution on As site (SbAs) has been proposed to understand the anomalous diffusion of defects during implant and their contribution to Al/Ga disordering during post‐implant annealing.
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73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Photoluminescence study of (111)‐oriented GaAs/GaAsP strained‐layer quantum well structure

Xiong Zhang, Koichi Karaki, Hiroyuki Yaguchi, Kentaro Onabe, Ryoichi Ito, and Yasuhiro Shiraki

Appl. Phys. Lett. 64, 1555 (1994); http://dx.doi.org/10.1063/1.111991 (3 pages) | Cited 3 times

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A GaAs/GaAs1−xPx (x=0.13) strained‐layer quantum well structure has been grown on (111)B‐oriented GaAs substrate by means of low‐pressure (60 Torr) metalorganic vapor phase epitaxy and characterized by photoluminescence (PL) spectroscopy. Despite the partial relaxation of the tensile strain confined in the GaAsP barrier layers, our sample exhibits smooth surface morphology and intense optical emission. Moreover, an evident blue shift of the excitonic transition peak attributed to the screening of the strain‐induced internal electric field by the photoexcited carriers, has been observed in the PL measurement.  
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63.20.D- Phonon states and bands, normal modes, and phonon dispersion
78.66.Fd III-V semiconductors
77.65.-j Piezoelectricity and electromechanical effects

Ion trajectory distortion and profile tilt by surface charging in plasma etching

Shigemi Murakawa, Sychyi Fang, and James P. McVittie

Appl. Phys. Lett. 64, 1558 (1994); http://dx.doi.org/10.1063/1.111864 (3 pages) | Cited 11 times

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Surface charging effects on etching profiles during silicon etching in a nonuniform plasma were investigated by scanning electron micrographs and plasma potential measurements. The distortion in ion trajectories caused by the surface charging was calculated by an ion lens simulator. A tilt in the etching profile was found in holes and trenches near a large etched area when an insulating mask such as photoresist or silicon dioxide was used. Ion trajectory calculations showed that this profile tilt was caused by the local electric field resulting from the potential difference between the charged mask surface and the electrically grounded silicon substrate. This profile result agrees well with gate oxide damage results which were also successfully explained by surface charging.
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81.65.-b Surface treatments
52.50.Gj Plasma heating by particle beams

Radiatively controlled lifetimes in AlxGa1−xAs grown by metalorganic vapor phase epitaxy

R. A. J. Thomeer, P. R. Hageman, and L. J. Giling

Appl. Phys. Lett. 64, 1561 (1994); http://dx.doi.org/10.1063/1.111865 (3 pages)

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We report long minority charge carrier lifetimes in AlxGa1−xAs/AlyGa1−yAs x<y) double heterostructures grown by metalorganic vapor phase epitaxy. The lifetime (τbulk=8.8 μs) is found to be controlled by radiative processes in samples with aluminum concentrations of x=0.10 for the active regime and y=0.20 for the cladding layers; an extremely low interface recombination velocity of S≂6.5 cm/s is found. At higher aluminum concentrations both the bulk and interface recombination rate increase rapidly.
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78.66.Fd III-V semiconductors
78.47.-p Spectroscopy of solid state dynamics
78.55.Cr III-V semiconductors

Exciton radiative lifetime in GaAs quantum wires grown by metalorganic chemical‐vapor selective growth

T. Kono, S. Tsukamoto, Y. Nagamune, F. Sogawa, M. Nishioka, and Y. Arakawa

Appl. Phys. Lett. 64, 1564 (1994); http://dx.doi.org/10.1063/1.111866 (3 pages) | Cited 9 times

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We discuss measurement results of the exciton radiative lifetime in GaAs quantum wires grown by metalorganic chemical‐vapor selective growth technique at 9 K. By changing the lateral width of the quantum wires in the range of 7–35 nm systematically, the lateral width dependence of the radiative exciton lifetime was measured. The results show that the measured lifetime increases from 260 to 422 ps with the decrease of the lateral width from 25 to 7 nm. This increase of the radiative lifetime can be explained by taking account of both reduced exciton coherence length and spreading of the wave function of electrons in the barrier region.  
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73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
78.47.-p Spectroscopy of solid state dynamics
78.55.Cr III-V semiconductors

Film thickness reduction of thermally annealed hydrogenated amorphous silicon prepared with plasma‐enhanced chemical vapor deposition

Y.‐K Yang, J.‐S. Shin, R.‐G. Hsieh, and J.‐Y. Gan

Appl. Phys. Lett. 64, 1567 (1994); http://dx.doi.org/10.1063/1.111841 (3 pages) | Cited 3 times

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The structural change of thermally annealed hydrogenated amorphous silicon films prepared with plasma‐enhanced chemical vapor deposition has been examined in this study. At 615 °C, a significant amount of microvoids can be annealed out of the silicon films. The annihilation of microvoids mainly causes the reduction of film thickness while the surface smoothness is largely retained. During annealing, the thickness of silicon films has been reduced by 220 Å from the initial thickness of 1200 Å. Evaluated with the thickness reduction alone, the void fraction of the as‐deposited films must be higher than 16%. The film thickness reduction starts at the very early stage of annealing and has almost completed within 30 min. Our results also have shown that the reduction of film thickness cannot be the result of crystallization, instead, it is more likely accompanied with the hydrogen effusion.
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81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization
61.72.Cc Kinetics of defect formation and annealing
61.72.Qq Microscopic defects (voids, inclusions, etc.)
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Microwave compatible YBa2Cu3O7−δ films on (001)MgF2 substrates

K. S. Harshavardhan, A. Pique, S. M. Green, K. Patel, J. R. Zhang, E. Belohoubek, R. Edwards, T. Venkatesan, E. J. Denlinger, V. Pendrick, D. Kalokitis, A. Fathy, X. D. Wu, M. Rajeswari, and A. Smith

Appl. Phys. Lett. 64, 1570 (1994); http://dx.doi.org/10.1063/1.111842 (3 pages) | Cited 2 times

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High quality YBa2Cu3O7−δ (YBCO) films have been epitaxially grown on low dielectric constant, low loss tangent (001)MgF2 substrates using a double buffer layer scheme. The YBCO films are (001) oriented, exhibit Tc’s of 88–89 K with transition widths ≤0.5 K and Jc’s of 4×106 A/cm2 at 77 K in zero field. Dielectric resonator experiments indicate unloaded Q values in excess of 30 000 at 77 K and 24 GHz in the unpatterned films. Films patterned into meanderline resonators and operating at 10 GHz, 79 K, exhibit surface resistance (Rs)<1 m Ω suggesting near‐future realization of low loss superconducting components in the millimeter‐wave region.
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74.78.-w Superconducting films and low-dimensional structures
74.25.N- Response to electromagnetic fields
85.25.Qc Superconducting surface acoustic wave devices and other superconducting devices

High quality crystalline YBa2Cu3O7−δ films on thin silicon substrates

R. Haakenaasen, D. K. Fork, and J. A. Golovchenko

Appl. Phys. Lett. 64, 1573 (1994); http://dx.doi.org/10.1063/1.111843 (3 pages) | Cited 11 times

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YBa2Cu3O7−δ(001) (YBCO) films with near perfect crystallinity have been grown epitaxially on Si(100) using two intermediate buffer layers: Yttrium‐stabilized zirconia (YSZ) and CeO2. All layers were grown by an in situ pulsed laser deposition process. The new films have Rutherford backscattering spectroscopy minimum yields as low as 5%, compared to 12% for YBCO films deposited directly on YSZ. The superconducting onset is above 90 K with a transition width ΔT of 1 K. After film deposition the Si substrate could be etched from the back to give a circular, 2‐mm‐ diam, 4000 Å uniformly thick Si membrane with 300 Å YSZ, 80 Å CeO2, and 1500–3000 Å YBCO on top.
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74.78.-w Superconducting films and low-dimensional structures
81.15.Np Solid phase epitaxy; growth from solid phases
68.60.-p Physical properties of thin films, nonelectronic
81.15.Fg Pulsed laser ablation deposition

Integrated micromachined magnetic field sensor with on‐chip support circuitry

M. Paranjape, I. Filanovsky, and Lj. Ristic

Appl. Phys. Lett. 64, 1576 (1994); http://dx.doi.org/10.1063/1.111844 (3 pages) | Cited 1 time

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This letter presents an integrated magnetic field sensor that has been fabricated in a standard complementary metal‐oxide semiconductor process. Along with the sensor, on‐chip circuitry has been realized to amplify the resulting Hall voltage signal. Furthermore, to increase device sensitivity, the sensor has been subjected to a post‐process etching step. The integrated sensor exhibits a ten times higher output signal compared with the output signal of the sensor alone.
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07.55.-w Magnetic instruments and components
73.40.Sx Metal-semiconductor-metal structures

Sputter deposited strontium ferrite films with c‐axis oriented normal to the film plane

B. Ramamurthy Acharya, R. Krishnan, Shiva Prasad, N. Venkataramani, Antony Ajan, and S. N. Shringi

Appl. Phys. Lett. 64, 1579 (1994); http://dx.doi.org/10.1063/1.111845 (3 pages) | Cited 7 times

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M‐type strontium ferrite films were deposited by radio‐frequency (rf) sputtering on fused quartz substrates kept at ambient temperatures. The as‐deposited films were amorphous. They crystallized on annealing at a temperature of 800 °C or higher. The films deposited at low rf power and low oxygen to argon ratio showed c‐axis orientation normal to the film plane. The magnetic properties of these films were studied using vibrating sample magnetometer, polar Kerr rotation, and torque magnetometer. The perpendicular M‐H loops for c‐axis oriented films were nearly rectangular with coercivity of the order of 3 kOe.
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75.70.Ak Magnetic properties of monolayers and thin films
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.50.Vv High coercivity materials

Laser assisted Pd seeding for electroless plating on SiO2

A. G. Schrott, B. Braren, and R. Saraf

Appl. Phys. Lett. 64, 1582 (1994); http://dx.doi.org/10.1063/1.111846 (3 pages) | Cited 7 times

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Excimer laser pulses with wavelengths of 248 and 308 nm were used to selectively seed Pd on SiO2 surfaces, making them suitable for electroless plating. This novel seeding process for insulating materials is accomplished with the sample immersed in the seeding solution, and occurs only on the areas of the substrate that are illuminated (through the liquid) by the laser light. The Pd content of the seeded samples increased with the number of pulses, but was rather independent of repetition rate. The deposition rate showed a dependence with wavelength consistent with a defect driven mechanism for electron excitation through the band gap of SiO2. These electrons then reduce the Pd ions in the solution in contact with the surface.
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81.15.Lm Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids)
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
68.08.-p Liquid-solid interfaces
68.43.-h Chemisorption/physisorption: adsorbates on surfaces

Glancing angle x‐ray diffraction: A different approach

B. A. van Brussel and J. Th. M. De Hosson

Appl. Phys. Lett. 64, 1585 (1994); http://dx.doi.org/10.1063/1.111847 (3 pages) | Cited 3 times

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This letter describes a novel technique of diffracted beam glancing angle x‐ray diffraction by which depth profiles of stresses and transformed phases in structures like implanted materials can be determined. An important feature is that this method may be applied successfully in a standard powder diffractometer. It is shown that, beside the well‐known incident beam glancing angle method which usually requires rather sophisticated equipment with parallel beam optics combined with more intense x‐ray sources, diffracted beam glancing angle x‐ray diffraction can be applied as well.
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61.05.cf X-ray scattering (including small-angle scattering)
61.05.cj X-ray absorption spectroscopy: EXAFS, NEXAFS, XANES, etc.

Scaling of ferroelectric properties in La‐Sr‐Co‐O/Pb‐La‐Zr‐Ti‐O/La‐Sr‐Co‐O capacitors

R. Ramesh, B. Dutta, T. S. Ravi, J. Lee, T. Sands, and V. G. Keramidas

Appl. Phys. Lett. 64, 1588 (1994); http://dx.doi.org/10.1063/1.111848 (3 pages) | Cited 31 times

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The scaling of ferroelectric properties with the capacitor size has been studied using epitaxial La‐Sr‐Co‐O/Pb‐La‐Zr‐Ti‐O/La‐Sr‐Co‐O heterostructures grown on Si. Discrete, large area capacitors were fabricated using a shadow mask or lift‐off process. Capacitors with areas smaller than 10−5 cm2 were fabricated by a full‐wafer process involving argon ion milling. The fatigue, aging, and retention characteristics of the capacitors fabricated by ion milling are commensurate with those of the discrete capacitors fabricated by the shadow mask technique. These results are very relevant with respect to the ultimate application of the capacitors in high density nonvolatile memories.
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77.80.-e Ferroelectricity and antiferroelectricity
62.20.M- Structural failure of materials

Pulsed excimer laser ablation of (Pb,La)TiO3 thin films for dynamic random access memory devices

G. Mohan Rao and S. B. Krupanidhi

Appl. Phys. Lett. 64, 1591 (1994); http://dx.doi.org/10.1063/1.111849 (3 pages) | Cited 25 times

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Polycrystalline (Pb,La)TiO3 thin films were deposited by pulsed excimer laser ablation on Si and Pt coated Si substrates. The crystallinity of the films showed dependence on the annealing temperature and oxygen pressure during ablation. Similar trends reflected in the dielectric behavior in terms of varying dielectric permittivity between 430–620 as the ablation pressure varied between 1 and 100 mTorr. Films exhibited the presence of ferroelectricity in terms of hysteresis in capacitance‐voltage characteristic in a metal‐ferroelectric‐metal configuration. The charge storage density estimated from the polarization measurements was about 10 μC/cm2, while a leakage current density of 10−8 A/cm2 was observed at an applied field of 100 kV/cm.
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77.55.-g Dielectric thin films
73.61.At Metal and metallic alloys
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