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3 Apr 1989

Volume 54, Issue 14, pp. 1287-1376

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‘‘Missing modes’’ in ion‐implanted LiNbO3 waveguides

P. J. Chandler, L. Zhang, J. M. Cabrera, and P. D. Townsend

Appl. Phys. Lett. 54, 1287 (1989); http://dx.doi.org/10.1063/1.101397 (3 pages) | Cited 20 times

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It is demonstrated that in optical waveguides formed by ion implantation in LiNbO3, the lower modes for the extraordinary index exist in a buried region of enhanced index, and so may be unable to couple with a surface prism. This is because a shallow region of slightly reduced index near to the surface necessitates the tunnelling of power to these ‘‘missing modes.’’ The number of such modes can be inferred from a comparison of data for two different wavelengths, and confirmation of this together with an estimation of their positions may be obtained by surface stripping. By taking them into account it has been possible to model the profile index by using a stepped base to the optical well.
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42.79.Gn Optical waveguides and couplers
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
61.72.up Other materials

Broadband all‐fiber filters for wavelength division multiplexing application

François Gonthier, Suzanne Lacroix, Xavier Daxhelet, Richard J. Black, and Jacques Bures

Appl. Phys. Lett. 54, 1290 (1989); http://dx.doi.org/10.1063/1.100737 (3 pages) | Cited 9 times

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In‐line spectral filters are designed and realized using the tapering technique to provide additional isolation to the demultiplexing fused fiber couplers. The typical performances obtained are less than 1 dB loss with more than 15 dB isolation in a 40 nm range around the desired wavelengths.
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42.79.Ci Filters, zone plates, and polarizers
42.79.Sz Optical communication systems, multiplexers, and demultiplexers
42.81.Wg Other fiber-optical devices
42.81.Qb Fiber waveguides, couplers, and arrays

Nonlinear optical susceptibilities of high‐index glasses

D. W. Hall, M. A. Newhouse, N. F. Borrelli, W. H. Dumbaugh, and D. L. Weidman

Appl. Phys. Lett. 54, 1293 (1989); http://dx.doi.org/10.1063/1.100697 (3 pages) | Cited 118 times

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We report results of degenerate four‐wave mixing measurements of nonresonant nonlinearities in a variety of high‐index lead and bismuth containing oxide glasses and the chalcogenide As2S3. The third‐order nonlinear susceptibilities of the oxide glasses are found to scale with the heavy metal content. A lead‐bismuth‐gallate glass was identified with a nonresonant χ3 equal to 42±7×10−14 esu, which is approximately three times larger than that of any glass previously reported.
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42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.65.Pc Optical bistability, multistability, and switching, including local field effects
78.20.-e Optical properties of bulk materials and thin films
42.70.Ce Glasses, quartz

Phase‐locked operation of a three‐element InGaAsP/InP grating‐surface‐emitting diode laser array

S. L. Palfrey, J. M. Hammer, P. A. Longeway, N. W. Carlson, G. A. Evans, J. T. Andrews, J. Jaklik, J. B. Kirk, R. Stolzenberger, and A. R. Triano

Appl. Phys. Lett. 54, 1296 (1989); http://dx.doi.org/10.1063/1.100698 (3 pages) | Cited 4 times

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Phased‐locked operation of a three‐element linear grating‐surface‐emitting laser diode array in the InGaAsP/InP material system is demonstrated. Far‐field patterns and spectra indicate coherence across the length of the array and dynamic wavelength stability due to grating feedback.
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42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.55.Px Semiconductor lasers; laser diodes
42.79.Sz Optical communication systems, multiplexers, and demultiplexers
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation

Tunable microwigglers for free‐electron lasers

S. C. Chen, G. Bekefi, S. DiCecca, and R. Temkin

Appl. Phys. Lett. 54, 1299 (1989); http://dx.doi.org/10.1063/1.100699 (3 pages) | Cited 7 times

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We present the design, construction, and test results of a novel microwiggler structure with a periodicity of 2.4 mm for free‐electron laser applications. The experimentally demonstrated tunability of field amplitude provides versatile means for field tapering, optical klystron configurations, improving field uniformity, and electron beam matching at the wiggler entrance.
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41.60.Cr Free-electron lasers
52.59.Px Hard X-ray sources
42.60.By Design of specific laser systems
42.60.Fc Modulation, tuning, and mode locking

35 GHz cyclotron autoresonance maser amplifier

G. Bekefi, A. DiRienzo, C. Leibovitch, and B. G. Danly

Appl. Phys. Lett. 54, 1302 (1989); http://dx.doi.org/10.1063/1.100700 (3 pages) | Cited 49 times

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Studies of a cyclotron autoresonance maser are presented. The measurements are carried out at a frequency of 35 GHz using a mildly relativistic electron beam (1.5 MeV, 260 A) generated by a field emission electron gun followed by an emittance selector that removes the outer, hot electrons. Perpendicular energy is imparted to the electrons by means of a bifilar helical wiggler. Measurements give a small signal gain of 90 dB/m and a saturated power output of 10 MW. The corresponding electronic efficiency is 3%. Computer simulations are also presented.
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84.40.Ik Masers; gyrotrons (cyclotron-resonance masers)
52.59.Px Hard X-ray sources
41.60.-m Radiation by moving charges
41.75.Ht Relativistic electron and positron beams

Measurements of gain, saturation, and line competition in an electron beam pumped high‐pressure Ar/Xe laser

Akira Suda, Bernard L. Wexler, Barry J. Feldman, and Kevin J. Riley

Appl. Phys. Lett. 54, 1305 (1989); http://dx.doi.org/10.1063/1.100701 (3 pages) | Cited 14 times

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Using a small electron beam device, we have observed time‐dependent competition among the 1.73, 2.03, 2.63, and 2.65 μm lines of the xenon laser in a high‐pressure argon buffer. The small‐signal gain and saturation intensity for each of these lines have also been measured. The maximum specific energy output of the laser was 1.7 J/l  and the efficiency was 2.3%.
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42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.55.Lt Gas lasers including excimer and metal-vapor lasers

Fuel areal density measurement of laser‐imploded targets by use of elastically scattered protons

H. Nakaishi, N. Miyanaga, H. Azechi, M. Yamanaka, T. Yamanaka, M. Takagi, T. Jitsuno, and S. Nakai

Appl. Phys. Lett. 54, 1308 (1989); http://dx.doi.org/10.1063/1.100702 (3 pages) | Cited 11 times

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A new method for the measurement of the density‐radius product (ρR) of laser‐imploded plasmas is presented. Deuterium‐tritium‐hydrogen fuel mixture is used and the spectrum of protons elastically scattered by 14.1 MeV neutrons is measured with nuclear emulsion. The reliability of this method was certified by comparing the inferred ρR value with that from the secondary reaction method in equivalent experimental conditions.
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52.70.Nc Particle measurements
52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
52.55.Pi Fusion products effects (e.g., alpha-particles, etc.), fast particle effects
52.25.Tx Emission, absorption, and scattering of particles

Defect structures in laser‐fused Si‐SiO2 wafers

M. L. Geyselaers, J. Haisma, F. P. Widdershoven, Th. M. Michielsen, and A. H. Reader

Appl. Phys. Lett. 54, 1311 (1989); http://dx.doi.org/10.1063/1.101398 (3 pages) | Cited 1 time

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A silicon‐on‐silicon dioxide structure (silicon‐on‐insulator) produced by combined ‘‘van der Waals’’ bonding and laser fusing has been studied by cross‐sectional transmission electron microscopy. Areas in the silicon corresponding to the regions which are locally melted by the laser beam were found to contain a high density of dislocations after fusing. The radius and depth of these defect areas, as observed in the microscope, are compared with a simple analytical model of the laser‐induced melting process.
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61.72.Bb Theories and models of crystal defects
07.79.Cz Scanning tunneling microscopes
61.05.-a Techniques for structure determination
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)

Diffusion of Si in thin CoSi2 layers

F. D. Schowengerdt, T. L. Lin, R. W. Fathauer, and P. J. Grunthaner

Appl. Phys. Lett. 54, 1314 (1989); http://dx.doi.org/10.1063/1.101399 (3 pages) | Cited 3 times

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We present evidence of Si diffusion in 100 Å layers of CoSi2 grown by room‐temperature codeposition and annealing on Si(111) substrates. By monitoring the intensity of the Co MVV and Si LVV Auger peaks, we find a Si‐rich surface layer after annealing, in agreement with the results of others. We find that this layer can be removed by chemical etching and re‐formed by subsequent annealing. By measuring the intensity of the plasmon energy loss peak associated with the Co L23 VV Auger peak, we conclude that the Si must exist on top of the CoSi2 and we obtain the effective Si overlayer thickness as a function of annealing temperature by calibrating the plasmon loss data against known overlayer thicknesses on unannealed samples. We find similar results on samples grown both with and without the addition of a 10 Å Si cap to prevent pinhole formation in the CoSi2 and we have indications that the same type of diffusion occurs also beneath the native oxide layer on samples that have not had the surface Si removed by chemical etching. In all of the samples studied, Si diffusion was observed to be non‐negligible at temperatures on the order of 400 °C, which is well below the point where pinhole formation is first observed. This result suggests that the diffusion does not depend on the presence of observable pinholes as previously thought.
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66.30.J- Diffusion of impurities
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
68.35.Dv Composition, segregation; defects and impurities
81.05.Bx Metals, semimetals, and alloys

Interfacial charge modification between SiO2 and silicon

S. Aronowitz, H. P. Zappe, and C. Hu

Appl. Phys. Lett. 54, 1317 (1989); http://dx.doi.org/10.1063/1.101400 (3 pages)

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A positive flatband voltage shift, ΔVfb ≂+0.4 V, with respect to unimplanted portions of the same wafer, was obtained when calcium (1×1013 cm−2) was implanted into 87 nm of thermally grown oxide on an n‐type 〈100〉 substrate and annealed. Calcium acts as a low‐efficiency n‐type dopant in silicon (<0.1% activated) which eliminates the possibility of calcium interactions in the substrate causing the flatband behavior. Calcium profiles after a 1100 °C anneal show considerable loss from the oxide but also indicate occurrence of stable sites in the SiO2 region near the oxide‐silicon interface. Theoretical calculations on a model SiO2 structure predict an effective negative charge at the Si/SiO2 interface due to calcium incorporation in agreement with the general behavior observed experimentally; moreover, the calculations predict that aluminum and strontium will behave in a similar fashion to calcium when implanted into SiO2 while boron will not.
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73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
61.72.up Other materials
61.72.sd Impurity concentration
61.72.sh Impurity distribution
61.72.sm Impurity gradients
73.20.Hb Impurity and defect levels; energy states of adsorbed species

Role of higher silanes in the plasma‐induced deposition of amorphous silicon from silane

M. Heintze and S. Vepřek

Appl. Phys. Lett. 54, 1320 (1989); http://dx.doi.org/10.1063/1.100703 (3 pages) | Cited 7 times

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Time‐resolved mass spectrometric data of the decay of monosilane concentration and of the formation and decay of disilane and trisilane are presented together with the silicon deposition rates measured under the same conditions. The data can be quantitatively explained by the mechanism involving, as a first step, the fragmentation of silane into SiH2 and H2, and deposition of a‐Si via higher silanes which are formed by a fast insertion reaction of silene into gaseous silanes. Deposition via a SiH3 radical, which has been suggested by several groups, cannot explain the experimental data.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
82.30.Lp Decomposition reactions (pyrolysis, dissociation, and fragmentation)

Time and temperature dependence of instability mechanisms in amorphous silicon thin‐film transistors

M. J. Powell, C. van Berkel, and J. R. Hughes

Appl. Phys. Lett. 54, 1323 (1989); http://dx.doi.org/10.1063/1.100704 (3 pages) | Cited 143 times

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We have measured the time and temperature dependence of the two prominent instability mechanisms in amorphous silicon thin‐film transistors, namely, the creation of metastable states in the a‐Si:H and the charge trapping in the silicon nitride gate insulator. The state creation process shows a power law time dependence and is thermally activated. The charge trapping process shows a logarithmic time dependence and has a very small temperature dependence. The results for the state creation process are consistent with a model of Si dangling bond formation in the bulk a‐Si:H due to weak SiSi bond breaking stabilized by diffusive hydrogen motion. The logarithmic time dependence and weak temperature dependence for the charge trapping in the nitride suggest that the charge injection from the a‐Si:H to the nitride is the rate limiting step and not subsequent conduction in the nitride.
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85.30.De Semiconductor-device characterization, design, and modeling
73.61.Cw Elemental semiconductors
73.61.Jc Amorphous semiconductors; glasses
73.61.Le Other inorganic semiconductors
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
73.61.Ng Insulators

Formation of planar superlattice states in new grid‐inserted quantum well structures

Masaaki Tanaka and Hiroyuki Sakaki

Appl. Phys. Lett. 54, 1326 (1989); http://dx.doi.org/10.1063/1.100705 (3 pages) | Cited 82 times

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We have prepared by molecular beam epitaxy a new type of planar superlattice (PSL), in which an array of periodically spaced AlAs bars of one monolayer (ML) in thickness is inserted in the middle of a GaAs quantum well. This grid‐inserted quantum well (GI–QW) is prepared on a misoriented GaAs substrate of 2° off from (001) axis by depositing 0.5 ML of AlAs during the growth of a usual QW. Photoluminescence excitation spectra are measured at 20 K and have shown a clear dependence on the polarization of the excitation light, reflecting the in‐plane anisotropy of electronic structures. The measured ratio of electron–heavy hole (e–hh) and electron–light hole (e–lh) transition peaks has shown the polarization dependence, which is in good agreement with theory; this demonstrates that 0.5 ML of AlAs atoms deposited on atomic terraces have formed a periodic potential as intended and given rise to the PSL states in this novel structure.
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73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors

Plasma‐enhanced chemical vapor deposited HgTe‐CdTe epitaxial superlattices

L. M. Williams, P.‐Y. Lu, and S. N. G. Chu

Appl. Phys. Lett. 54, 1329 (1989); http://dx.doi.org/10.1063/1.100706 (3 pages) | Cited 3 times

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For the first time, small‐period epitaxial superlattices were grown using plasma‐enhanced chemical vapor deposition. The superlattices were periods of HgTe‐CdTe grown on CdTe substrates at 150 °C using dimethylcadmium, dimethylmercury, and dimethyltelluride. Cross‐section transmission electron microscopy shows that layers as thin as 80 Å were obtained.
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68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
81.15.Kk Vapor phase epitaxy; growth from vapor phase
68.55.-a Thin film structure and morphology
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Structural properties of ultrathin arsenic‐doped layers in silicon

M. W. Denhoff, T. E. Jackman, J. P. McCaffrey, J. A. Jackman, W. N. Lennard, and G. Massoumi

Appl. Phys. Lett. 54, 1332 (1989); http://dx.doi.org/10.1063/1.100707 (3 pages) | Cited 12 times

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We have grown δ‐doped layers in Si by low‐energy As‐ion implantation during molecular beam epitaxy. The layers were investigated using cross‐sectional transmission electron microscopy, secondary‐ion mass spectrometry, Rutherford backscattering, and electrical measurements. The δ‐doped layers were between 3.5 and 5.5 nm thick, and showed perfect epitaxy with 50–80% of the incorporated As on substitutional sites. Layers doped at concentrations from 1×1013 cm−2 to 8×1013 cm−2 had bulk‐like mobilities and spanned the metal to insulator transition.
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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
73.61.Cw Elemental semiconductors
73.61.Jc Amorphous semiconductors; glasses
73.61.Le Other inorganic semiconductors
73.50.Dn Low-field transport and mobility; piezoresistance

Stepped‐gate‐oxide structure—A new approach for speed enhancement in the gate‐controlled photodetector

C. C. Sun and J. M. Xu

Appl. Phys. Lett. 54, 1335 (1989); http://dx.doi.org/10.1063/1.100708 (3 pages)

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In this letter, we report a stepped‐gate‐oxide structure implemented in the gate‐controlled photodetector. The experimental results show that a one‐order‐of‐magnitude enhancement in the response speed can be achieved by the use of such a structure owing to the induced transverse electrical field.
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85.60.Dw Photodiodes; phototransistors; photoresistors
85.60.Gz Photodetectors (including infrared and CCD detectors)

Plasma‐assisted epitaxial growth of InAs

Sun Fei Fang, Koichi Matsushita, and Takashi Hariu

Appl. Phys. Lett. 54, 1338 (1989); http://dx.doi.org/10.1063/1.101354 (3 pages) | Cited 4 times

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InAs layers were epitaxially grown directly on GaAs, InP, and GaSb at relatively low temperatures by plasma‐assisted epitaxy (PAE) in hydrogen plasma. The electronic and crystallographic properties of PAE‐InAs grown on substrates with different lattice mismatch were comparatively studied with a variable supply ratio As/In, growth temperature, and thickness of grown films. The electronic properties of PAE‐InAs films comparable to those by molecular beam epitaxy (MBE) were obtained in a wide range of supply ratio, with less supply ratio, and at lower temperatures than MBE.
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81.15.Kk Vapor phase epitaxy; growth from vapor phase
68.55.-a Thin film structure and morphology
81.15.Rs Spray coating techniques
73.61.Ey III-V semiconductors

Γ‐ and X‐state influences on resonant tunneling current in single‐ and double‐barrier GaAs/AlAs structures

Kenneth V. Rousseau, K. L. Wang, and J. N. Schulman

Appl. Phys. Lett. 54, 1341 (1989); http://dx.doi.org/10.1063/1.100709 (3 pages) | Cited 29 times

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We have calculated the resonant tunneling current of electrons in single‐ and double‐barrier GaAs‐AlAs heterostructures in the (001) direction. A ten‐band empirical tight‐binding model is used in which the wave function is propagated through the structure from atom to atom using transfer matrices. We find that electrons generally follow a Γ‐Γ‐Γ‐Γ‐Γ or Γ‐X‐X‐X‐Γ path through the double‐barrier devices, and present curves that show Γ resonances and X resonances as distinct peaks in the transmission coefficient. The tunneling current is calculated and the influence of the different types of resonances is discussed for a double‐barrier device. The existence of resonances in the AlAs barriers suggests that negative differential resistance effects can exist in single‐barrier devices.
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73.40.Gk Tunneling
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

Effect of boron on the deep donors (DX centers) in GaAs:Si

M. F. Li, Peter Y. Yu, W. Shan, W. Hansen, and E. R. Weber

Appl. Phys. Lett. 54, 1344 (1989); http://dx.doi.org/10.1063/1.100710 (3 pages) | Cited 8 times

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We found that, when boron was introduced into GaAs:Si, the deep donors induced by pressure exceeding 20 kbar reported previously by M. Mizuta, M. Tachikawa, H. Kukimoto, and S. Minomura [J. Appl. Phys. 24, L143 (1985)] disappeared while new donor levels with reduced binding energies and capture barrier heights appeared. It is proposed that B atoms paired up with Si donor atoms and the resultant change in the short‐range potential of the Si donor atoms depressed the capture barrier height of the pressure‐induced deep donor.
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71.55.Eq III-V semiconductors

Cathodoluminescence measurement of an orientation dependent aluminum concentration in AlxGa1−xAs epilayers grown by molecular beam epitaxy on a nonplanar substrate

Michael E. Hoenk, Howard Z. Chen, Amnon Yariv, Hadis Morkoç, and Kerry J. Vahala

Appl. Phys. Lett. 54, 1347 (1989); http://dx.doi.org/10.1063/1.100711 (3 pages) | Cited 11 times

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Cathodoluminescence scanning electron microscopy is used to study AlxGa1−x As epilayers grown on a nonplanar substrate by molecular beam epitaxy. Grooves parallel to the [011] direction were etched in an undoped GaAs substrate. Growth on such grooves proceeds on particular facet planes. We find that the aluminum concentration in the epilayers is dependent on the facet orientation, changing by as much as 35% from the value in the unpatterned areas. The transition in the aluminum concentration at a boundary between two facets is observed to be very abrupt.
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78.60.Hk Cathodoluminescence, ionoluminescence
68.55.-a Thin film structure and morphology
68.55.Nq Composition and phase identification
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Dopant distribution for maximum carrier mobility in selectively doped Al0.30Ga0.70As/GaAs heterostructures

E. F. Schubert, Loren Pfeiffer, K. W. West, and A. Izabelle

Appl. Phys. Lett. 54, 1350 (1989); http://dx.doi.org/10.1063/1.100712 (3 pages) | Cited 15 times

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The magnitude of potential fluctuations due to remote ionized dopants is calculated for selectively doped heterostructures using unscreened and screened Coulomb potentials. Potential fluctuations are found to be minimized (corresponding to maximum carrier mobility) if the dopant distribution is δ‐function‐like. Our experimental study of electron mobilities in selectively doped heterostructures grown by molecular beam epitaxy reveals that carrier mobility indeed increases as the thickness of the doped layer is reduced, in agreement with the calculation. A peak electron mobility of 5.5×106 cm2 /V s is obtained at low temperatures in a selectively δ‐doped heterostructure.
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73.50.Dn Low-field transport and mobility; piezoresistance
73.61.Ey III-V semiconductors
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

Room‐temperature exciton optical absorption peaks in InGaAsP/InP multiple quantum wells

M. Sugawara, T. Fujii, S. Yamazaki, and K. Nakajima

Appl. Phys. Lett. 54, 1353 (1989); http://dx.doi.org/10.1063/1.100713 (3 pages) | Cited 7 times

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We grew In1−xGaxAsyP1−y/InP quantum wells (QWs) by low‐pressure metalorganic vapor phase epitaxy. The In1−xGaxAsyP1−y layer was closely lattice matched to InP with a composition of y=0.9 (x=0.47y). We investigated structural imperfections such as composition fluctuations, interface roughness, and nonperiodicity analyzing the low‐temperature photoluminescence linewidth. We found that the InGaAsP layer composition fluctuated, causing about 5 meV inhomogeneity in the exciton energy level in QWs wider than about 3 nm. Since we obtained very smooth interfaces with less than one monolayer of fluctuation and excellent periodicity by lowering growth temperature to 570 °C, the inhomogeneity of the exciton energy level could be held at 6 meV for 20‐period 10‐nm multiple QWs. As a result, despite composition fluctuations, a clear room‐temperature exciton optical absorption peak was observed at 1.5 μm for the first time to our knowledge.
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68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
81.15.Kk Vapor phase epitaxy; growth from vapor phase
71.35.-y Excitons and related phenomena
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems

Band‐edge absorption coefficients from photoluminescence in semiconductor multiple quantum wells

Alan Kost, H. C. Lee, Yao Zou, P. D. Dapkus, and Elsa Garmire

Appl. Phys. Lett. 54, 1356 (1989); http://dx.doi.org/10.1063/1.100714 (3 pages) | Cited 3 times

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We describe a novel approach to determining absorption coefficients in thin films using luminescence. The technique avoids many of the difficulties typically encountered in measurements of thin samples, Fabry–Perot effects, for example, and can be applied to a variety of materials. We examine the absorption edge for GaAs/AlGaAs multiple quantum well structures with quantum well widths ranging from 54 to 193 Å. Urbach parameters and excitonic linewidths are tabulated.
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78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
78.55.Cr III-V semiconductors
73.61.Ey III-V semiconductors
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems

Low interface state density at an epitaxial ZnSe/epitaxial GaAs interface

Q.‐D. Qian, J. Qiu, M. R. Melloch, J. A. Cooper, L. A. Kolodziejski, M. Kobayashi, and R. L. Gunshor

Appl. Phys. Lett. 54, 1359 (1989); http://dx.doi.org/10.1063/1.100715 (3 pages) | Cited 23 times

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The capacitance‐voltage (C‐V) and the current‐voltage characteristics of metal/ZnSe/p‐GaAs capacitors have been investigated; both epitaxial layers were grown by molecular beam epitaxy. In the capacitor structures highly resistive, stoichiometric ZnSe functioned as the pseudoinsulator on the doped GaAs layers. The capacitance‐voltage measurements demonstrated that the capacitors could be biased from accumulation through depletion, and into deep depletion, with current in the range of 10−8 A cm−2. Very little frequency dispersion was observed in the C‐V data when measured from 1 kHz to 1 MHz. From the high‐frequency C‐V curve, the surface state density as a function of position in the GaAs band gap was determined. Surface state densities were comparable to densities reported for (Al,Ga)As/GaAs heterojunctions.
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73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.20.At Surface states, band structure, electron density of states
73.40.Ns Metal-nonmetal contacts
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