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1 Feb 1988

Volume 52, Issue 5, pp. 339-413

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Near‐ideal low threshold behavior in (111) oriented GaAs/AlGaAs quantum well lasers

T. Hayakawa, T. Suyama, K. Takahashi, M. Kondo, S. Yamamoto, and T. Hijikata

Appl. Phys. Lett. 52, 339 (1988); http://dx.doi.org/10.1063/1.99457 (3 pages) | Cited 39 times

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Fundamental characteristics of (111) oriented GaAs/AlGaAs graded‐index separate‐confinement‐heterostructure single quantum well lasers have been compared with conventional (100) oriented lasers. In particular, the threshold current density Jth of (111) oriented lasers does not change with the well width Lz in the range of Lz=30–100 Å, which corresponds to an ideal extreme. The lowest Jth of 145 A/cm2 together with a high characteristic temperature T0 of 186 K in the threshold‐temperature dependence has been achieved for an Lz of 40 Å and a cavity length of 490 μm. The dependence of T0 on Lz showed that T0 is maximum at Lz∼60 Å for both (111) and (100) oriented lasers.
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42.60.Da Resonators, cavities, amplifiers, arrays, and rings
78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
42.55.Px Semiconductor lasers; laser diodes
78.45.+h Stimulated emission

CdS photoelectric device: Modulation and optical bistability at 514 nm

A. Witt, M. Wegener, C. Klingshirn, D. Gnass, and D. Jäger

Appl. Phys. Lett. 52, 342 (1988); http://dx.doi.org/10.1063/1.99458 (3 pages) | Cited 6 times

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We discuss the nonlinear characteristics of hybrid CdS devices at room temperature by using increasing absorption at a wavelength of 514.5 nm. Via the thermo‐optical properties, a self‐electro‐optic effect occurs due to the optically induced dissipation of electrical power. As a special application, the device can be utilized as an electro‐optic modulator for Ar+ laser light. In addition, voltage controlled optical bistability is also observed.
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85.60.-q Optoelectronic devices
78.20.Jq Electro-optical effects
42.65.Pc Optical bistability, multistability, and switching, including local field effects
42.79.Hp Optical processors, correlators, and modulators

Experimental confirmation of a sum rule for room‐temperature electroabsorption in GaAs‐AlGaAs multiple quantum well structures

M. Whitehead, G. Parry, K. Woodbridge, P. J. Dobson, and G. Duggan

Appl. Phys. Lett. 52, 345 (1988); http://dx.doi.org/10.1063/1.99459 (3 pages) | Cited 22 times

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Measurements of the electric field dependence of room‐temperature photocurrent in a GaAs‐A10.4Ga0.6As multiple quantum well p‐i‐n diode have been carried out in the wavelength range 650–920 nm. Calculations of the field dependence of absorption from the photocurrent spectra show that the recently derived sum rule for electroabsorption in quantum wells holds to within 0.3%, for electric fields as high as 2×105 V/cm, provided that full account is taken of changes in absorption across the entire spectral region.
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78.20.Jq Electro-optical effects
85.60.Dw Photodiodes; phototransistors; photoresistors
78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
72.40.+w Photoconduction and photovoltaic effects

Actively mode‐locked GaInAsP laser with subpicosecond output

S. W. Corzine, J. E. Bowers, G. Przybylek, U. Koren, B. I. Miller, and C. E. Soccolich

Appl. Phys. Lett. 52, 348 (1988); http://dx.doi.org/10.1063/1.99460 (3 pages) | Cited 25 times

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We actively mode lock a high‐frequency GaInAsP laser at a rate of 16 GHz to obtain nearly transform‐limited hyperbolic secant pulses with a pulse width of 0.58 ps. This is the shortest pulse width yet demonstrated for either passively or actively mode‐locked semiconductor lasers.
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42.60.Fc Modulation, tuning, and mode locking
42.55.Px Semiconductor lasers; laser diodes
42.79.Sz Optical communication systems, multiplexers, and demultiplexers
42.65.Re Ultrafast processes; optical pulse generation and pulse compression

Birefringent channel waveguides defined by impurity‐induced superlattice disordering

E. Kapon, N. G. Stoffel, E. A. Dobisz, and R. Bhat

Appl. Phys. Lett. 52, 351 (1988); http://dx.doi.org/10.1063/1.99461 (3 pages) | Cited 28 times

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The waveguiding characteristics of GaAs/AlGaAs channel waveguides defined by silicon‐induced superlattice disordering were investigated at 1.15 μm wavelength. These waveguides guide laterally only TE‐polarized light. Because of the birefringence of the superlattice core of the waveguide, only the TE mode experiences a positive refractive index step between the unmixed and disordered superlattices. The TM mode, on the other hand, experiences a negative refractive index step resulting in antiguiding. The operation of these waveguides as efficient waveguide polarizers is demonstrated.
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42.79.Gn Optical waveguides and couplers
42.82.-m Integrated optics
42.79.Sz Optical communication systems, multiplexers, and demultiplexers
78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors

Pulse compression effect in a laser‐driven flash x‐ray tube

P. Krehl

Appl. Phys. Lett. 52, 354 (1988); http://dx.doi.org/10.1063/1.99462 (2 pages) | Cited 2 times

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The performance characteristics of a high‐vacuum discharge flash x‐ray tube, such as dose, maximum dose rate, discharge delay time, and pulse width, can be improved by triggering the tube with a laser‐produced plasma at the cathode. The system consists of an open flash x‐ray diode of classical coaxial electrode geometry, driven at 50 kV by a 10 Ω, 69 ns transmission line and a neodymium:yttrium aluminum garnet laser of 10 ns pulse width, which is focused onto the cathode rim. It could be demonstrated that already at small incident laser energy a significant x‐ray pulse compression could be achieved, which also goes in parallel with an increase in dose output. Experiments with laser energies at 110 mJ indicate a saturation in optimum tube performance.
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52.80.Vp Discharge in vacuum
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
52.50.Dg Plasma sources
52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)

Ion‐induced C segregation on Fe films on pyrolytic graphite under high‐fluence D bombardment

A. Santaniello, J. Bohdansky, and J. Roth

Appl. Phys. Lett. 52, 356 (1988); http://dx.doi.org/10.1063/1.99463 (3 pages) | Cited 6 times

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Fe films of 700–1700 Å were evaporated on pyrolytic graphite surfaces with both edge and base orientations, and bombarded with D ions at energies from 2 to 13 keV at fluences of 1019 D/cm2. The different ion energies and Fe film thicknesses allow different defect distributions in the graphite substrate of the samples. The Fe sputtering yield of the samples was measured directly by means of laser‐induced fluorescence at temperatures ranging from room temperature to 900 K. The depth distribution of the components during mixing is obtained by means of Rutherford backscattering spectroscopy. At 800 K, a drastic reduction of the Fe sputtering yield is observed if energetic ions can reach the graphite substrate. C segregates on top of the Fe layers for D ion ranges larger than the Fe layer thickness. The thickness of the segregated C layers depends on the graphite orientation. For 13 keV D bombardment of 700 Å Fe samples, for example, it is about 100 Å for base graphite and about 1000 Å for edge graphite.
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61.80.Jh Ion radiation effects
68.35.Fx Diffusion; interface formation
68.35.Dv Composition, segregation; defects and impurities
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces

Nonlinear optical absorption in an n‐InGaAsP/p‐InP heterodoping superlattice

H. Kobayashi, Y. Yamauchi, and H. Ando

Appl. Phys. Lett. 52, 359 (1988); http://dx.doi.org/10.1063/1.99464 (3 pages) | Cited 4 times

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Absorptive optical nonlinearity in an n‐InGaAsP/p‐InP heterodoping superlattice grown by vapor phase epitaxy is investigated. Although change in the absorption coefficient per an excited carrier obtained for the doping superlattice is comparable to that of bulk material, larger nonlinear absorption is induced by unit‐intensity light illumination. This enhancement is attributable to prolonged carrier recombination lifetime due to the separation of electrons and holes in space. The nonlinear absorption caused by accumulated photocarriers can be explained by the combination of two effects: blocking of direct band‐to‐band transition in real space (band filling effect), and change in probability of indirect transition in real space (Franz–Keldysh effect) due to a modified internal electric field.
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78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
42.65.-k Nonlinear optics
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths

Observation of tilt boundaries in graphite by scanning tunneling microscopy and associated multiple tip effects

T. R. Albrecht, H. A. Mizes, J. Nogami, Sang‐il Park, and C. F. Quate

Appl. Phys. Lett. 52, 362 (1988); http://dx.doi.org/10.1063/1.99465 (3 pages) | Cited 75 times

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Tilt boundaries have been observed on the (0001) surface of graphite by scanning tunneling microscopy (STM). Rotation angles about the c axis of 6.5°, 8°, and 19° were found, indicating no preferential orientation of grains in the basal plane of graphite. The grain boundary region between crystallites appears disordered with a width varying between 10 and 100 Å. Moiré patterns are observed near grain boundaries when multiple tips scanning over different grains contribute to the image simultaneously. Such images support the theory that multiple isolated tips, occasionally hundreds of angstroms apart, can contribute to STM images.
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61.72.Mm Grain and twin boundaries
07.79.Cz Scanning tunneling microscopes
61.05.-a Techniques for structure determination

Sputtering of silicon dioxide near threshold

S. S. Todorov and E. R. Fossum

Appl. Phys. Lett. 52, 365 (1988); http://dx.doi.org/10.1063/1.99466 (3 pages) | Cited 10 times

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The sputtering rate for silicon dioxide by argon ion bombardment at energies appropriate for ion beam deposition (<100 eV) has been measured. It has been found that the energy dependence of the oxide sputtering rate at these low energies is easily predicted by assuming the yield is limited by the metallic component of the binary target. This assumption is shown to predict also the sputtering rate of other metallic oxides.
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79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
81.15.Cd Deposition by sputtering
81.05.Kf Glasses (including metallic glasses)
81.65.-b Surface treatments
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy

Multiphoton ionization of aluminum and copper planar target

C. O. Park, H. W. Lee, T. D. Lee, and J. K. Kim

Appl. Phys. Lett. 52, 368 (1988); http://dx.doi.org/10.1063/1.99467 (3 pages) | Cited 3 times

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The total charge of the emitted ions from the planar metal targets irradiated by the mode‐locked ruby laser was measured. The dependence of the total emitted ions on the laser fluence is consistent with the theory of the multiphoton ionization in the low fluence region. However, it shows saturation phenomena at the higher fluence regions. These saturations could be explained by the depletion of the neutral atoms and the level shifting of the intermediate state due to the strong Stark effect.
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79.20.Ds Laser-beam impact phenomena
32.80.Fb Photoionization of atoms and ions
32.60.+i Zeeman and Stark effects
32.80.Rm Multiphoton ionization and excitation to highly excited states

Determination of pairwise interaction potential parameters from a double scattering experiment

W. Hetterich, H. Derks, and W. Heiland

Appl. Phys. Lett. 52, 371 (1988); http://dx.doi.org/10.1063/1.99468 (2 pages) | Cited 10 times

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The backscattering of K+ from an Ir(110) surface is used to determine the parameters of the screening function of the interaction potential. The energy range used (from 0.3 to 6 keV) corresponds to a potential range from 10 to 4000 eV. In the case studied the J. F. Ziegler, J. P. Biersack, U. Littmark [Stopping Powers and Ranges of Ions in Matter, edited by J. F. Ziegler (Pergamon, New York, 1985)] (ZBL) universal screening function gives a better fit to the experiment than the G. Molière [Z. Naturf. 2a, 133 (1947)] screening function.
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79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces

Scaling and renormalization in transmittance of thin metal films near the percolation threshold

Y. Yagil and G. Deutscher

Appl. Phys. Lett. 52, 373 (1988); http://dx.doi.org/10.1063/1.99469 (2 pages) | Cited 29 times

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Recent transmittance measurements of thin metal films near the percolation threshold Pc [Y. Yagil and G. Deutscher, Thin Solid Films 152, 456 (1987)] are interpreted by scaling arguments reflecting the special structure of the film near Pc. Based on the claim that the relevant length scale over which the optical properties are measured is the optical wave number 1/k=λ/2π, we present an argument showing how the optical transmittance scales with this quantity. Our interpretation, based on real‐space renormalization, yields a power law wavelength dependence near the percolation threshold, with a coefficient that vanishes at Pc.
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78.66.Bz Metals and metallic alloys

Polyimide on copper: The role of solvent in the formation of copper precipitates

Steven P. Kowalczyk, Young‐Ho Kim, G. F. Walker, and J. Kim

Appl. Phys. Lett. 52, 375 (1988); http://dx.doi.org/10.1063/1.99470 (2 pages) | Cited 37 times

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The interaction at the polyimide‐copper (oxide) interface has been investigated by means of cross‐sectional transmission electron microscopy. By using a solventless molecular beam epitaxy growth technique, the role of solvent in the aggregation and diffusion of copper‐rich particles into the polyimide film and away from the interface was unambiguously demonstrated. The polyimide on copper growth sequence is contrasted to the copper on polyimide growth sequence, and the reasons for the differences between the two growth interfaces are discussed.
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68.35.Fx Diffusion; interface formation
81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
81.65.-b Surface treatments
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Controversy of critical layer thickness for InGaAs/GaAs strained‐layer epitaxy

P. L. Gourley, I. J. Fritz, and L. R. Dawson

Appl. Phys. Lett. 52, 377 (1988); http://dx.doi.org/10.1063/1.99471 (3 pages) | Cited 100 times

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The critical layer thickness for InxGa1−xAs layers in InxGa1−xAs/GaAs single strained quantum wells (SSQW’s) and strained‐layer superlattices (SLS’s) are investigated. Photoluminescence microscopy (PLM) images and x‐ray rocking curves for two series of SSQW and SLS structures corresponding to many different layer thicknesses were obtained. We find that the PLM technique, which directly images dislocations and is sensitive to low dislocation densities, is much more suitable for determining the onset of dislocation creation. The x‐ray technique can detect lattice relaxation by dislocations but only at relatively high densities of dislocations. Using the former technique, we determine critical thicknesses of 190 Å for SSQW’s and 250 Å for SLS’s with x≊0.2. These results are near the theoretical predictions of J. W. Matthews, S. Mader, and T. B. Light [J. Appl. Phys. 41, 3800 (1970)] (150 and 300 Å, respectively) and are much lower than results obtained by x‐ray or other techniques which sense lattice relaxation.
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68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
68.55.-a Thin film structure and morphology
78.55.Cr III-V semiconductors

Determination of the critical layer thickness of Si1−xGex/Si heterostructures by direct observation of misfit dislocations

Y. Kohama, Y. Fukuda, and M. Seki

Appl. Phys. Lett. 52, 380 (1988); http://dx.doi.org/10.1063/1.99472 (3 pages) | Cited 58 times

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The dependence of the critical layer thickness hc on mole fraction x of Si1−xGex/Si heterostructures is determined by direct observations of misfit dislocations by using the electron beam induced current (EBIC) technique and transmission electron microscopy (TEM). The EBIC images of the Si1−xGex/Si interfaces show square‐grid patterns running in the 〈110〉 directions. These patterns are identified by TEM observation to be misfit dislocations generated at the Si1−xGex/Si interface. The dependence of hc on x is compared with the results reported by R. People and J. C. Bean [Appl. Phys. Lett. 47, 322 (1985) and 49, 229 (1986)]. The comparison reveals that inconsistency exists between them, especially in the range of x<0.3. This inconsistency is considered to arise from the difference in the techniques adopted to determine the hc’s.
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68.35.Dv Composition, segregation; defects and impurities
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.55.-a Thin film structure and morphology
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Direct evidence of the DX center link to the L‐conduction‐band minimum in GaAlAs

E. Calleja, A. Gomez, and E. Muñoz

Appl. Phys. Lett. 52, 383 (1988); http://dx.doi.org/10.1063/1.99473 (3 pages) | Cited 43 times

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Hydrostatic pressure techniques together with deep level transient spectroscopy (DLTS) measurements have shown that the Si‐DX center in GaAlAs is linked to the L‐conduction‐band minimum. When hydrostatic pressure is applied to a 74% Al content sample, an exponential reduction of the DLTS signal is observed. This exponential dependence with pressure arises from the reduction of the DX filling factor (electron occupancy) due to the increasing X‐L energy difference with pressure. Our results, together with previous data, also show that the capture barrier height originating from the lattice relaxation is an intrinsic parameter of both the material and the donor species, that does not depend on Al content or conduction‐band structure.
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71.55.Eq III-V semiconductors
71.20.Nr Semiconductor compounds
71.20.Ps Other inorganic compounds

Thermal desorption of oxides on InP

W. M. Lau, R. N. S. Sodhi, and S. Ingrey

Appl. Phys. Lett. 52, 386 (1988); http://dx.doi.org/10.1063/1.99474 (3 pages) | Cited 11 times

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The thermal desorption of thin oxide films on n‐ and p‐type InP has been studied by using x‐ray photoelectron spectroscopy. It was found that oxides formed on InP could be completely desorbed at 458 °C without causing surface decomposition. The phosphorus and indium oxides desorbed together within 5°. However, heating the oxidized surface to about 453 °C, while not changing the chemical structure of the phosphorus oxides, did remove a significant amount of indium oxides. Heating at this lower temperature also induced changes of the position of the surface Fermi level. On n‐InP, it changes from 0.1 eV below the conduction‐band minimum to 0.3 eV, and on p‐InP, from 0.6 to 0.4 eV. Upon complete desorption of all surface oxides at 458 °C, the Fermi level on n‐InP was then pinned at 0.3 eV, whereas that of p‐InP moved down to 0.9 eV. This suggests a reduction of donor defects. Heating the surface of 458 °C for more than a few minutes or heating at a slightly higher temperature caused a loss of phosphorus. On such a decomposed surface, the Fermi level of n‐InP was pinned at 0.5 eV and p‐InP at 0.7 eV, which indicates the formation of more donor and acceptor defects.
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68.43.-h Chemisorption/physisorption: adsorbates on surfaces
68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics

Donor identification in bulk gallium arsenide

T. D. Harris, M. S. Skolnick, J. M. Parsey, and R. Bhat

Appl. Phys. Lett. 52, 389 (1988); http://dx.doi.org/10.1063/1.99475 (3 pages) | Cited 2 times

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We report identification, by a spectroscopic method, of shallow donors in both epitaxial and bulk gallium arsenide. Identification is achieved using photoluminescence from resonantly excited two‐electron satellites of donor bound exciton lines at 4.2 K in a magnetic field of 9.5 T. Sulfur and a previously unreported lower binding energy donor dominate in liquid‐encapsulated Czochralski‐grown crystals, while S and Si are dominant in the Bridgman‐grown material. Central cell structure is resolved in the (D0,X) lines in a high magnetic field.
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71.55.Eq III-V semiconductors
61.72.sd Impurity concentration
61.72.sh Impurity distribution
61.72.sm Impurity gradients
71.35.-y Excitons and related phenomena
78.55.Cr III-V semiconductors

Organometallic epitaxy of HgCdTe on CdTeSe substrates with high compositional uniformity

Sorab K. Ghandhi, Ishwara B. Bhat, and Hamid Fardi

Appl. Phys. Lett. 52, 392 (1988); http://dx.doi.org/10.1063/1.99476 (3 pages) | Cited 20 times

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We report here on the growth of Hg0.8Cd0.2Te on lattice‐matched substrates of CdTe0.96Se0.04 by organometallic vapor phase epitaxy. Results are compared with those for comparable layers grown on CdTe substrates. It is shown that the use of lattice‐matched substrates results in active layers of improved structural quality, as evidenced by the results of double‐crystal x‐ray diffraction measurements. A compositional uniformity of better than ±0.005 (in the Cd composition) was obtained over 1 cm ×2 cm area substrates, corresponding to a standard deviation of 0.0024. The thickness uniformity was better than ±0.7 μm for 12‐μm‐thick layers. These layers were deposited by the direct alloy growth, without the interdiffusion of separate layers of HgTe and CdTe. Both n‐ and p‐type layers have been grown by suitable modification to the growth process. Mobility values in excess of 6×105 cm2/V s were obtained in n‐type material (x=0.2), with an electron concentration below 1×1015 cm−3. With p‐type layers, mobility values of 400 cm2/V s were obtained with a hole concentration of 1×1017 cm−3.
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81.15.Kk Vapor phase epitaxy; growth from vapor phase
68.55.-a Thin film structure and morphology
73.61.Ga II-VI semiconductors
68.55.Nq Composition and phase identification

Formation of thermally stable high‐resistivity AlGaAs by oxygen implantation

S. J. Pearton, M. P. Iannuzzi, C. L. Reynolds, and L. Peticolas

Appl. Phys. Lett. 52, 395 (1988); http://dx.doi.org/10.1063/1.99477 (3 pages) | Cited 47 times

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Oxygen implantation into n+‐AlGaAs, followed by annealing above 600 °C, creates a deep acceptor level that compensates the shallow donors present in the material. Temperature‐dependent Hall measurements show that the resistivity of this compensated AlGaAs has a thermal activation energy of 0.49 eV, in contrast to a value of 0.79 eV for compensation caused by ion‐induced damage. The latter is stable only to 600 °C, whereas the chemically induced compensation in O‐implanted AlGaAs is stable above 950 °C.
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68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
68.60.Dv Thermal stability; thermal effects
73.61.Ey III-V semiconductors
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)

Quantum well tunnel triode

A. Kastalsky and M. Milshtein

Appl. Phys. Lett. 52, 398 (1988); http://dx.doi.org/10.1063/1.99478 (3 pages) | Cited 3 times

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We demonstrate a novel three‐terminal device, the tunnel triode, in which the current within the quantum well is a part of the tunnel current through the p+‐n+ junction. A tunnel‐diode‐like negative differential resistance effect with peak‐to‐valley ratio as high as 20 was observed, the tunnel current being controlled by the gate voltage. We show that tunneling occurs not in the quantum well, but in the heavily doped n+‐Al0.3Ga0.7As layer, and it is preceded by a real‐space hot‐electron transfer from the quantum well into this layer. Logic operation of a bistable switch was obtained in a circuit comprising a tunnel triode and a series resistance.
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85.30.Mn Junction breakdown and tunneling devices (including resonance tunneling devices)
84.32.Dd Connectors, relays, and switches
07.50.Ek Circuits and circuit components
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

Photoluminescence identification of residual donors in undoped GaAs grown by metalorganic chemical vapor deposition

S. P. Watkins, G. Haacke, and H. Burkhard

Appl. Phys. Lett. 52, 401 (1988); http://dx.doi.org/10.1063/1.99479 (3 pages) | Cited 14 times

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A photoluminescence technique was used to identify residual donors in the 1014 cm−3 range in high‐purity GaAs grown by metalorganic chemical vapor deposition. The measurements were taken at zero magnetic field. A narrow‐linewidth tunable laser was used to resonantly enhance a specific narrow‐linewidth ‘‘two‐electron’’ satellite line of the donor‐bound exciton, enabling determination of the 1s‐to‐2s donor energy separations. Ge was identified as the dominant residual donor. Lower levels of the donors X1 and X2 were observed in some samples. These are attributed to Si (or possibly Sn) and S donors.
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78.55.Cr III-V semiconductors
71.35.-y Excitons and related phenomena
71.55.Eq III-V semiconductors

Reversible laser chemically induced phase transformations in thin‐film Ba2YCu3Ox superconductors

M. Rothschild, J. H. C. Sedlacek, J. G. Black, and D. J. Ehrlich

Appl. Phys. Lett. 52, 404 (1988); http://dx.doi.org/10.1063/1.99452 (3 pages) | Cited 15 times

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Phase transformations of a thin film of Ba2YCu3Ox were induced with a focused laser beam in chemical ambients. The transformations, involving superconductive and nonsuperconductive phases, are achieved rapidly and with a high degree of spatial control. They are fully reversible, and the appropriate processing parameters have been studied. These effects are interpreted within present models, which relate the superconducting properties of Ba2YCu3Ox to its oxygen content and crystalline structure.
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74.20.Mn Nonconventional mechanisms
74.20.Rp Pairing symmetries (other than s-wave)
74.70.-b Superconducting materials other than cuprates
64.70.K- Solid-solid transitions
74.78.-w Superconducting films and low-dimensional structures

High-efficiency, laser grooved, buried contact silicon solar cells

Chee Mun Chong, Stuart R. Wenham, and Martin A. Green

Appl. Phys. Lett. 52, 407 (1988); http://dx.doi.org/10.1063/1.99453 (3 pages) | Cited 9 times

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Improvements in the performance of silicon solar cells based on a novel, laser grooved, buried contact approach are described. Independently confirmed energy conversion efficiencies as high as 19.8% are reported for cells of 12 cm2 area, as are the resistivity dependence of efficiency, spectral response data, and the results of laser beam induced current scans. The potential for further improvement is also discussed.
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84.60.Jt Photoelectric conversion
72.40.+w Photoconduction and photovoltaic effects
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