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26 Feb 1990

Volume 56, Issue 9, pp. 799-874

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Blue light‐emitting organic electroluminescent devices

Chihaya Adachi, Tetsuo Tsutsui, and Shogo Saito

Appl. Phys. Lett. 56, 799 (1990); http://dx.doi.org/10.1063/1.103177 (3 pages) | Cited 327 times

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Organic electroluminescent (EL) devices with multilayered thin‐film structures which emitted bright blue light were constructed. Two empirical guides for the selection of blue‐emitting materials were established. The keys to obtain the EL cells with high EL efficiency were excellent film‐forming capability of an emitter layer and the appropriate combinations of emitter and carrier transport materials for avoiding the formation of exciplexes. In one of our organic electroluminescent devices, blue emission with a luminance of 700 cd/m2 was achieved at a current density of 100 mA/cm2 and a dc drive voltage of 10 V.
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72.80.Le Polymers; organic compounds (including organic semiconductors)
85.60.Jb Light-emitting devices

Low‐loss GaAs/AlGaAs optical waveguides and phase modulator on silicon substrate grown by molecular beam epitaxy

Y. S. Kim, S. S. Lee, R. V. Ramaswamy, S. Sakai, Y. C. Kao, and H. Shichijo

Appl. Phys. Lett. 56, 802 (1990); http://dx.doi.org/10.1063/1.102668 (3 pages) | Cited 3 times

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We report on the fabrication and the characterization of low‐loss, single‐mode GaAs/AlGaAs single heterostructure ridge waveguides and a linear electro‐optic phase modulator on silicon substrate. The waveguides and the phase modulator were grown by molecular beam epitaxy and were characterized at a 1.3 μm wavelength. The average TE mode propagation loss of 1.24 dB/cm, obtained for a 6‐μm‐wide ridge waveguide, is the lowest loss so far reported. The measured phase shift efficiency of the phase modulator was 3.5°/V mm.
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42.79.Gn Optical waveguides and couplers
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
42.79.Hp Optical processors, correlators, and modulators

Tunable diode laser frequency modulation spectroscopy through an optical fiber: High‐sensitivity detection of water vapor

Clinton B. Carlisle and David E. Cooper

Appl. Phys. Lett. 56, 805 (1990); http://dx.doi.org/10.1063/1.102669 (3 pages) | Cited 17 times

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Frequency modulation spectroscopy through a single‐mode optical fiber has been demonstrated for monitoring H2O vapor at 7665 cm−1. Using a 2.5 mW distributed feedback laser and 100 m of optical fiber, a minimum detectable absorption of 5×10−7 was achieved. To obtain this sensitivity limit, very large spurious signals and technical noise were suppressed using a dual‐channel detection scheme.
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07.07.-a General equipment
07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques
33.20.-t Molecular spectra
42.81.Wg Other fiber-optical devices

Diode array side‐pumped neodymium‐doped gadolinium scandium gallium garnet rod and slab lasers

David P. Caffey, Richard A. Utano, and Toomas H. Allik

Appl. Phys. Lett. 56, 808 (1990); http://dx.doi.org/10.1063/1.102670 (3 pages) | Cited 6 times

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Gadolinium scandium gallium garnet (GSGG) was studied as a high average power laser host material utilizing diode array side pumping. Maximum optical slope efficiencies of 41.5% for Nd:GSGG in the rod geometry and 32.5% for a Nd:Cr:GSGG zig‐zag slab were obtained at 1.06 μm. Nd:GSGG and Nd:YAG have similar fluorescence lifetimes while Nd:GSGG has better energy storage capabilities due to its smaller stimulated‐emission cross section.
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42.55.Rz Doped-insulator lasers and other solid state lasers
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation

Simultaneous three primary color laser emissions from dye mixtures

Y. Saito, M. Kato, A. Nomura, and T. Kano

Appl. Phys. Lett. 56, 811 (1990); http://dx.doi.org/10.1063/1.103319 (3 pages) | Cited 10 times

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Simultaneous two‐ and three‐band laser emissions were obtained in a process of mixing two and three kinds of dyes excited by a nitrogen laser. They were blue, green, and yellow in a coumarin 460 (C460)/disodium fluorescein (DF)/rhodamine 610 (R610) dye mixture, and blue, green, and red in a C460/DF/rhodamin 640 (R640) dye mixture. Strong energy transfers from DF to R610 and to R640 were shown. R610 and R640 laser emissions on mixing with DF were obtained at very low concentrations. They were 4×10−6 mol/l  for R610 and 1×10−5 mol/l  for R640, compared to the lasing threshold concentration of 1×10−4 and 2×10−4 mol/l  of each dye alone. Also, the R610 radiation moved about 35 nm to a shorter wavelength at the reduced concentration.
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42.55.Mv Dye lasers
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.60.By Design of specific laser systems

cw passive mode locking of a Ti:sapphire laser

Nobuhiko Sarukura, Yuzo Ishida, Hidetoshi Nakano, and Yoshihisa Yamamoto

Appl. Phys. Lett. 56, 814 (1990); http://dx.doi.org/10.1063/1.102671 (2 pages) | Cited 13 times

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cw passive mode locking of a Ti:sapphire laser is achieved with 1,1′‐dietyl‐2,2′‐dicarbocyanine iodide as the saturable absorber dye, using a 5 μm thin dye jet flow. The pulse width is 4.0 ps, which is almost the transform‐limited pulse for the observed spectrum width. The output power is ∼50 mW, when it is pumped by a 5 W cw Ar laser, while the tuning range is 745–755 nm.
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42.60.By Design of specific laser systems
42.15.Eq Optical system design
42.55.Rz Doped-insulator lasers and other solid state lasers
42.70.-a Optical materials

External‐cavity InGaAs/InP graded index multiquantum well laser with a 200 nm tuning range

A. Lidgard, T. Tanbun‐Ek, R. A. Logan, H. Temkin, K. W. Wecht, and N. A. Olsson

Appl. Phys. Lett. 56, 816 (1990); http://dx.doi.org/10.1063/1.102672 (2 pages) | Cited 11 times

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A tuning range of 200 nm has been achieved with a step‐graded multiquantum well InGaAs/InP laser in an external‐cavity configuration. Continuous, single‐mode lasing could be observed from 1440 to 1640 nm. Depending on the current density, the laser can operate both at the n=1 and n=2 quantized states. At low current density, the n=1 state gives higher gain, whereas for higher carrier densities, the n=2 level dominates. This gives rise to a flat gain profile and an extended operating range, in fact, the widest tuning range reported so far for semiconductor lasers.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Fc Modulation, tuning, and mode locking

Diagnostics of high‐frequency discharges in CH4/H2 by time‐ and space‐resolved optical emission spectroscopy

Terukazu Kokubo, Fumiyoshi Tochikubo, and Toshiaki Makabe

Appl. Phys. Lett. 56, 818 (1990); http://dx.doi.org/10.1063/1.103320 (3 pages) | Cited 24 times

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The diagnostic technique of the rf glow discharge at 13.56 MHz is developed by using the spatiotemporally resolved optical emission spectroscopy. New experimental evidence that the temporal excitation rate at the sheath peaks in phase with the maximum of the total current is obtained in a parallel‐plate geometry at 13.56 MHz in CH4(10%)/H2 under a typical condition of the plasma chemical vapor deposition of amorphous carbon film at room temperature.
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52.80.Hc Glow; corona
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
07.60.Rd Visible and ultraviolet spectrometers

Real‐time, in situ monitoring of GaAs and AlGaAs photoluminescence during plasma processing

Annette Mitchell, Richard A. Gottscho, Stephen J. Pearton, and Geoffrey R. Scheller

Appl. Phys. Lett. 56, 821 (1990); http://dx.doi.org/10.1063/1.102673 (3 pages) | Cited 8 times

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Monitoring wafer changes in situ during plasma treatment provides real‐time feedback for developing and controlling device processing. In this letter we report the use of photoluminescence spectroscopy to monitor epitaxial films of Al0.3Ga0.7As and semi‐insulating GaAs substrates during BCl3 plasma etching and H2 plasma passivation. Photoluminescence monitoring is used for etching endpoint detection, surface damage quantification, and wafer temperature measurement.
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81.65.-b Surface treatments
78.55.Cr III-V semiconductors
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
85.40.Hp Lithography, masks and pattern transfer

Velocity electric field relationship for minority electrons in highly doped p‐GaAs

T. Furuta and M. Tomizawa

Appl. Phys. Lett. 56, 824 (1990); http://dx.doi.org/10.1063/1.102674 (3 pages) | Cited 19 times

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Using the time‐of‐flight method, the drift velocity for minority electrons in highly doped p‐GaAs was successfully measured at room temperature. The obtained velocity electric field relationships indicate that the velocity does not decrease but slightly increases and then saturates with increasing hole concentration above 1×1019 cm−3. Such behavior is well explained by the effects of degeneracy, which reduces the electron‐hole interaction, and the hole distribution function dependence on electric field from the Monte Carlo calculation.
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72.20.-i Conductivity phenomena in semiconductors and insulators
72.20.Ht High-field and nonlinear effects
72.20.Dp General theory, scattering mechanisms

Atomic layer epitaxy of GaP and elucidation for self‐limiting mechanism

Y. Sakuma, K. Kodama, and M. Ozeki

Appl. Phys. Lett. 56, 827 (1990); http://dx.doi.org/10.1063/1.102675 (3 pages) | Cited 9 times

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Atomic layer epitaxy (ALE) of GaP was performed for the first time in a low‐pressure metalorganic vapor phase epitaxial (MOVPE) reactor using trimethylgallium (TMG) and phosphine (PH3) as sources. Growth was self‐limiting for the exposure time of each reactant. X‐ray photoelectron spectroscopy (XPS) analyses were carried out to identify the adsorbates on the growth surface. There were no methyl groups on the surface Ga and the self‐limiting mechanism is due to the selective adsorption of TMG by the surface P atoms. When the substrate was exposed to a sufficient TMG flow after a submonolayer Ga was deposited by triethylgallium (TEG), growth was still self‐limiting. This supports the selective adsorption model.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
81.15.Kk Vapor phase epitaxy; growth from vapor phase
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces

Microfabrication and optical study of reactive ion etched InGaAsP/InP and GaAs/GaAlAs quantum wires

A. Izrael, B. Sermage, J. Y. Marzin, A. Ougazzaden, R. Azoulay, J. Etrillard, V. Thierry‐Mieg, and L. Henry

Appl. Phys. Lett. 56, 830 (1990); http://dx.doi.org/10.1063/1.102676 (3 pages) | Cited 28 times

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Microfabrication of reactive ion etched InGaAsP/InP and GaAs/GaAlAs quantum wire structures with dimensions down to 30 nm has been achieved. From time‐resolved photoluminescence, the importance of surface recombination effects is outlined in both systems. It is shown that the use of epitaxial overgrowth leads to a significant increase of the carrier lifetime in GaAs/GaAlAs wires, so that emission of very narrow wires (width<40 nm) can be detected. The possible assignment of the observed shifts of the cw photoluminescence peak energies to additional lateral confinement effects is discussed.
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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

Conduction‐ and valence‐band offsets in GaAs/Ga0.51In0.49P single quantum wells grown by metalorganic chemical vapor deposition

D. Biswas, N. Debbar, P. Bhattacharya, M. Razeghi, M. Defour, and F. Omnes

Appl. Phys. Lett. 56, 833 (1990); http://dx.doi.org/10.1063/1.102677 (3 pages) | Cited 81 times

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We have independently estimated the conduction‐ and valence‐band offsets ΔEc and ΔEv in GaAs/Ga0.51In0.49P quantum wells by measuring the capacitance transient resulting from thermal emission of carriers from the respective wells. The heterostructure samples were grown by low‐pressure metalorganic chemical vapor deposition. The band offsets are extrapolated from the emission activation energies with appropriate corrections. The estimated values of ΔEc and ΔEv are 0.198 and 0.285 eV, respectively.
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73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
81.15.Kk Vapor phase epitaxy; growth from vapor phase
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

Carbon tetrachloride doped AlxGa1−xAs grown by metalorganic chemical vapor deposition

B. T. Cunningham, J. E. Baker, and G. E. Stillman

Appl. Phys. Lett. 56, 836 (1990); http://dx.doi.org/10.1063/1.103321 (3 pages) | Cited 13 times

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A dilute mixture of CCl4 in H2 has recently been shown to be a suitable carbon doping source for obtaining p‐type GaAs grown by metalorganic chemical vapor deposition (MOCVD) with carbon acceptor concentrations in excess of 1×1019 cm−3. To understand the effect of growth parameters on carbon incorporation in CCl4‐doped AlxGa1−xAs, carbon acceptor concentration was studied as a function of Al composition, growth temperature, growth rate, and CCl4 flow rate using electrochemical capacitance‐voltage profiling. The carbon incorporation as a function of Al composition, growth temperature, and CCl4 flow rate was also measured by secondary‐ion mass spectroscopy. All layers were grown by low‐pressure MOCVD using TMGa and TMAl as column III precursors, and 100% AsH3 as the column V source. Increased Al composition reduced the dependence of carbon concentration on the growth temperature. Reduced growth rate, which resulted in substantially decreased carbon acceptor concentrations in GaAs, had an insignificant effect on the carrier concentration of Al0.4Ga0.6As. A linear relationship between hole concentration and CCl4 flow rate in AlxGa1−xAs for 0.0≤x≤0.8 was observed. These results are interpreted to indicate that adsorption and desorption of CCly (y≤3) on the AlxGa1−xAs surface during crystal growth plays an important role in the carbon incorporation mechanism.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
71.55.Eq III-V semiconductors

Reactive ion beam etching of ZnSe and ZnS epitaxial films using Cl2 electron cyclotron resonance plasma

Tohru Saitoh, Toshiya Yokogawa, and Tadashi Narusawa

Appl. Phys. Lett. 56, 839 (1990); http://dx.doi.org/10.1063/1.102678 (3 pages) | Cited 7 times

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Reactive ion beam etching of ZnSe and ZnS epitaxial films was carried out using pure Cl2 as an etching gas. Electron cyclotron resonance plasma was excited at pressures of 2.5×10−4 –2.5×10−3 Torr. Chlorine ions were extracted with voltages of 0–400 V. Sputtering yields were strongly dependent on the extraction voltage and the gas pressure. The etching mechanism starts with the generation of chloride compounds, mainly ZnClx, by the chemical reaction of the surface and chlorine radicals, mainly Cl atoms. The chloride compounds are subsequently sputtered off by the accelerated ion beam. The crystalline quality of etched ZnSe films was characterized by photoluminescence measurements. We found that high quality etched films, which have almost no damage and no Cl contamination, can be obtained at an extraction voltage of about 300 V.
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81.65.-b Surface treatments
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces

Electrical characteristics of p+‐Ge/(N‐GaAs and N‐AlGaAs) junctions and their applications to Ge base transistors

M. S. Ünlü, S. Strite, G. B. Gao, K. Adomi, and H. Morkoç

Appl. Phys. Lett. 56, 842 (1990); http://dx.doi.org/10.1063/1.102679 (3 pages) | Cited 13 times

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Electrical properties of p+‐Ge/N‐AlGaAs (and N‐GaAs) are studied as a function of temperature and current conduction mechanisms are outlined. Junctions with Ge grown on GaAs and AlGaAs show ideality factors of unity and 1.03 at room temperature, respectively. Temperature‐dependent current‐voltage (I‐V) and room‐temperature capacitance‐voltage (C‐V) characterization are employed to determine the built‐in voltage (Vbi) of the two diode structures. For Ge/GaAs, a valence‐band discontinuity of 0.49±0.05 eV is measured which is in good agreement with the value deduced from photoemission studies. Implications of p+‐Ge base in AlGaAs/Ge/GaAs double‐heterojunction bipolar transistors (DHBTs) are discussed.
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73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
85.30.De Semiconductor-device characterization, design, and modeling
73.61.Ey III-V semiconductors
73.61.Cw Elemental semiconductors
73.61.Jc Amorphous semiconductors; glasses
73.61.Le Other inorganic semiconductors

Low‐temperature growth of ZnSe by molecular beam epitaxy using cracked selenium

D. A. Cammack, K. Shahzad, and T. Marshall

Appl. Phys. Lett. 56, 845 (1990); http://dx.doi.org/10.1063/1.102680 (3 pages) | Cited 10 times

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The growth of zinc selenide by molecular beam epitaxy using a cracked selenium source is studied. It is found that high quality growth can be achieved at substantially lower substrate temperatures than has been possible using uncracked selenium sources. It is determined from reflection high‐energy electron diffraction observations that the use of cracked selenium produces growth dominated by a two‐dimensional mechanism at substrate temperatures as low as 225 °C and that exposure of the GaAs substrate to cracked selenium prior to the initiation of growth has a substantial effect on the GaAs substrate and the early stages of ZnSe growth.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
81.10.Aj Theory and models of crystal growth; physics and chemistry of crystal growth, crystal morphology, and orientation
61.72.U- Doping and impurity implantation

Low‐temperature growth of ZnSe by molecular beam epitaxy using cracked selenium

H. Cheng, J. M. DePuydt, M. Haase, and J. E. Potts

Appl. Phys. Lett. 56, 848 (1990); http://dx.doi.org/10.1063/1.102681 (3 pages) | Cited 6 times

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Growth of high quality ZnSe films has been achieved at growth temperatures as low as 150 °C by using elemental zinc and thermally cracked selenium as source materials. Crystallinity of the films was determined by the Zn/Se flux ratio rather than by the growth rate; it was possible to grow good crystalline films at growth rates from 0.5 to 1 μm/h. Photoluminescence and x‐ray measurements indicated that there is little degradation in the film quality as the growth temperature is lowered from 350 to 150 °C.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.-a Thin film structure and morphology
78.55.Et II-VI semiconductors
68.60.Wm Other nonelectronic physical properties

High sensitivity low dark current 10 μm GaAs quantum well infrared photodetectors

B. F. Levine, C. G. Bethea, G. Hasnain, V. O. Shen, E. Pelve, R. R. Abbott, and S. J. Hsieh

Appl. Phys. Lett. 56, 851 (1990); http://dx.doi.org/10.1063/1.102682 (3 pages) | Cited 178 times

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By increasing the quantum well barrier width, we have dramatically reduced the tunneling dark current by an order of magnitude and thereby significantly increased the blackbody detectivity D@B|BB. For a GaAs quantum well infrared detector having a cutoff wavelength of λc=10.7 μm, we have achieved D∗BB =1.0×1010 cm (Hz)1/2/W at T=68 K, a temperature which is readily achievable with a cryogenic cooler.
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85.60.Gz Photodetectors (including infrared and CCD detectors)
73.50.Pz Photoconduction and photovoltaic effects
73.61.Ey III-V semiconductors
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems

Direct imaging of δ‐doped layers in GaAs

A. Ourmazd, J. Cunningham, W. Jan, J. A. Rentschler, and W. Schröter

Appl. Phys. Lett. 56, 854 (1990); http://dx.doi.org/10.1063/1.103185 (3 pages) | Cited 18 times

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We report the direct imaging of Be δ‐doped layers in GaAs, in the concentration range (0.5–2)×1014/cm2, comparing samples grown by gas source molecular beam epitaxy (MBE) and conventional MBE. The gas source MBE δ layers are ∼15 Å wide, and at least at high concentrations, consist of clusters ∼12 Å in diameter. At 2×1014 Be atoms/cm2, the MBE δ layer is an order of magnitude wider than that grown at the same temperature by gas source MBE. Our results imply that layers with Be concentrations in excess of 1021/cm3 can be fabricated by gas source MBE.
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68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
07.79.Cz Scanning tunneling microscopes
61.05.-a Techniques for structure determination
68.35.B- Structure of clean surfaces (and surface reconstruction)

Si/SiO2 etch properties using CF4 and CHF3 in radio frequency cylindrical magnetron discharges

Geun Young Yeom and Mark J. Kushner

Appl. Phys. Lett. 56, 857 (1990); http://dx.doi.org/10.1063/1.103322 (3 pages) | Cited 6 times

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Si/SiO2 etch properties have been studied in CF4 and CHF3 cylindrical magnetron rf discharges as a function of magnetic field strength. As the magnetic field strength increases from 0 to 250 G, radical densities continuously increase and dc bias voltages exponentially decrease. The maximum etch rates of Si and SiO2, however, occur at an intermediate value of magnetic field strength which corresponds to the self‐bias voltage being between 25 and 50 V. Using magnetic field strengths near the maximum etch rate, we obtained vertical features having <2000 Å widths and trenches deeper than 2 μm. Etch rates exceeding 2500 Å/min were obtained in a CF4 plasma, with little or no radiation damage, and with minimum contamination of the surface.
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81.65.-b Surface treatments
81.05.Kf Glasses (including metallic glasses)
52.80.Pi High-frequency and RF discharges
52.40.Hf Plasma-material interactions; boundary layer effects

Implant isolation of GaAs‐AlGaAs heterojunction bipolar transistor structures

F. Ren, S. J. Pearton, W. S. Hobson, T. R. Fullowan, J. Lothian, and A. W. Yanof

Appl. Phys. Lett. 56, 860 (1990); http://dx.doi.org/10.1063/1.102683 (3 pages) | Cited 22 times

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The formation of high‐resistivity (>107Ω/☒) regions in GaAs‐AlGaAs heterojunction bipolar transistor (HBT) structures by oxygen and hydrogen ion implantation has been investigated as a function of ion dose and subsequent annealing temperature (400–700 °C). Isolation leakage currents as low as 8 μA mm−1 at 6 V can be achieved between 100‐μm‐wide ohmic contacts separated by a 16 μm spacing. The isolation of these 1.8‐μm‐thick heterojunctions requires up to six different energy oxygen implants (40–400 keV) and three different energy proton implants (100–200 keV) with doses in the mid 1012 cm−2 range for O+ and 5×1014 cm−2 for H+ ions. Similar results can be achieved by substituting a MeV energy oxygen implant for the proton implants. The optimum post‐implant annealing temperature depends on the ion dose but is in the range 500–600 °C. The evolution of the sheet resistance of the implanted GaAs‐AlGaAs material with annealing is consistent with a reduction in tunneling probabilities of trapped carriers between deep level states for temperatures up to ∼600 °C, followed by significant annealing of these deep levels. Small geometry (2×9 μm2) HBTs exhibiting current gain of 44 and cutoff frequency fT as high as 45 GHz are demonstrated using implant isolation.
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85.30.Pq Bipolar transistors
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
81.40.Rs Electrical and magnetic properties related to treatment conditions
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Organometallic chemical vapor deposition of InP/InGaAsP on nonplanar InP substrates: Application to multiple quantum well lasers

R. Bhat, E. Kapon, J. Werner, D. M. Hwang, N. G. Stoffel, and M. A. Koza

Appl. Phys. Lett. 56, 863 (1990); http://dx.doi.org/10.1063/1.102665 (3 pages) | Cited 11 times

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We report the growth of InGaAs and InGaAsP quantum well heterostructures on InP substrates with [011] oriented grooves. We have shown that growth of these materials on non‐planar substrates can result in lattice‐mismatched layers on orientations other than (100) which in some cases gives rise to dislocations. In addition, the lateral patterning of quantum wells and quantum wire‐like structures has been demonstrated in this material system. Finally, a quantum well laser, wherein lateral patterning of the well thickness was achieved by growing in a flat‐bottomed groove, was fabricated. Without any additional growth steps these lasers exhibit a single stable spatial mode due to the waveguide formed at the groove.
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68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
42.55.Px Semiconductor lasers; laser diodes
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Relationship between etch pit densities and oxygen concentrations on CdTe

Katsuhiro Yokota, Toshiharu Yoshikawa, Sigeru Inano, Takeshi Morioka, and Saichi Katayama

Appl. Phys. Lett. 56, 866 (1990); http://dx.doi.org/10.1063/1.102666 (2 pages) | Cited 11 times

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The density of etch pits and the concentration of O in melt‐grown CdTe increased as the residual gas pressure in ampoules during preparation increased. The etch pit density increased proportionally to the integral strength of an infrared TeO2 absorption band, which presents the oxygen concentration.
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61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
78.30.-j Infrared and Raman spectra
78.40.Fy Semiconductors
61.72.sd Impurity concentration
61.72.sh Impurity distribution
61.72.sm Impurity gradients
81.65.-b Surface treatments

High coercivity in mechanically alloyed Sm‐Fe‐V magnets with a ThMn12 crystal structure

L. Schultz, K. Schnitzke, and J. Wecker

Appl. Phys. Lett. 56, 868 (1990); http://dx.doi.org/10.1063/1.102662 (3 pages) | Cited 23 times

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Microcrystalline Sm‐Fe‐V magnets with a ThMn12 crystal structure were prepared by mechanical alloying and a subsequent reaction heat treatment. In Sm15Fe70V15 a coercivity of 11.7 kOe is obtained. This is the best value reported so far for 1:12 magnets. As expected from their high anisotropy fields, the 1:12 magnets, therefore, show coercivities which are common in the Nd‐Fe‐B system.
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75.50.Vv High coercivity materials
81.20.Ev Powder processing: powder metallurgy, compaction, sintering, mechanical alloying, and granulation
81.40.Rs Electrical and magnetic properties related to treatment conditions
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