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25 Sep 1989

Volume 55, Issue 13, pp. 1273-1365

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Observation of ultrashort (<4 ps) gain‐switched optical pulses from long‐wavelength multiple quantum well lasers

Radhakrishnan Nagarajan, Takeshi Kamiya, Akihiko Kasukawa, and Hiroshi Okamoto

Appl. Phys. Lett. 55, 1273 (1989); http://dx.doi.org/10.1063/1.101630 (3 pages) | Cited 8 times

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Optical pulses of less than 4 ps full width at half maximum have been generated by electrical gain switching of long‐wavelength multiple quantum well lasers, and were observed directly on a streak camera. This is the first ever generation of optical pulses of such short duration using direct electrical gain switching. We have identified the higher differential gain due to the second quantized state transition in the multiple quantum well laser to be responsible for the generation of these ultrashort optical pulses. We also discuss the possible resolution limits of the streak camera measurement system.
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42.55.Px Semiconductor lasers; laser diodes
42.55.Rz Doped-insulator lasers and other solid state lasers
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Effects of excimer laser irradiation on the transmission, index of refraction, and density of ultraviolet grade fused silica

M. Rothschild, D. J. Ehrlich, and D. C. Shaver

Appl. Phys. Lett. 55, 1276 (1989); http://dx.doi.org/10.1063/1.102471 (3 pages) | Cited 68 times

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Radiation‐induced changes in high‐purity fused silica during prolonged irradiation with a pulsed laser at 193 nm have been studied. Radiolytically induced UV absorption bands, an increase in index of refraction, and stress birefringence are observed. The formation mechanisms are analyzed in terms of radiolytic atomic rearrangement of a‐SiO2 initiated by two‐photon absorption. The quantum efficiency for the formation of E′ point defects per pair of absorbed 193 nm photons has been determined to be ∼7.5×10−4; matrix compaction, as high as a few parts in 10−5, is identified as the source of the birefringence and index change. It has been further observed that E′ centers can be photobleached.
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81.40.Tv Optical and dielectric properties related to treatment conditions
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
78.30.Hv Other nonmetallic inorganics
78.40.Ha Other nonmetallic inorganics

Frequency modulation responses of two‐electrode distributed feedback lasers

C. Y. Kuo, Y. Twu, N. K. Dutta, E. J. Wagner, and S. W. Granlund

Appl. Phys. Lett. 55, 1279 (1989); http://dx.doi.org/10.1063/1.101631 (3 pages) | Cited 2 times

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Frequency modulation (FM) response of a 1.3 μm two‐electrode distributed feedback laser is studied in detail. We found that by adjusting the injection current applied to the modulated section, the FM bandwidth can be increased to a value as high as 900 MHz. However, as the bandwidth increases, the FM sensitivity decreases proportionally. This behavior is described satisfactorily by below‐threshold carrier rate equation and shown to be closely related to the injected carrier lifetime.
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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
42.82.-m Integrated optics

Excited‐state absorption in HgBr

J. H. Schloss and J. G. Eden

Appl. Phys. Lett. 55, 1282 (1989); http://dx.doi.org/10.1063/1.101632 (3 pages) | Cited 1 time

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The photoabsorption spectrum of the lowest ion pair state (B2Σ+1/2 ) of HgBr has been measured in the visible and ultraviolet (280≤λ≤480 nm) by laser excitation spectroscopy. Several previously unreported bands, peaking at 289, 302, 318, 330, 340, 364–373, and 401 nm, are observed and provide a stringent test for ab initio calculations of the excited state interaction potentials for the diatomic radical. A highly structured band lying between ∼444 and 470 nm confirms the observations of D. P. Greene, K. P. Killeen, and J. G. Eden [J. Chem. Phys. 85, 3188 (1986)] in a laser discharge. Also, the spectra fully resolve the apparent discrepancy between recent, unsuccessful attempts to produce a HgBr laser by flashlamp pumping the B←X band and experiments in which short pulse (8–25 ns) laser excitation of this transition has generated 502 nm coherent radiation with an energy conversion efficiency exceeding 20% [D. P. Greene, K. P. Killeen and J. G. Eden, Appl. Phys. Lett. 48, 1175 (1986)].
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33.20.Kf Visible spectra
33.20.Lg Ultraviolet spectra
42.55.Lt Gas lasers including excimer and metal-vapor lasers
33.80.Gj Diffuse spectra; predissociation, photodissociation

Stimulated emission from a Hg1−xCdxTe epilayer grown by molecular beam epitaxy

K. K. Mahavadi, J. Bleuse, X. Chu, and J. P. Faurie

Appl. Phys. Lett. 55, 1285 (1989); http://dx.doi.org/10.1063/1.101633 (2 pages) | Cited 12 times

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We report on the observation of stimulated emission from a (100) oriented Hg1−xCdxTe epilayer grown by molecular beam epitaxy. The cleaved epilayers were cooled and optically pumped by a Nd:YAG laser and were found to lase continuously up to 40 K.
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78.45.+h Stimulated emission
42.55.Px Semiconductor lasers; laser diodes
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
42.55.-f Lasers

Off‐resonant third‐order optical nonlinearities of metal‐substituted phthalocyanines

James S. Shirk, J. R. Lindle, F. J. Bartoli, C. A. Hoffman, Zakya H. Kafafi, and Arthur W. Snow

Appl. Phys. Lett. 55, 1287 (1989); http://dx.doi.org/10.1063/1.101634 (2 pages) | Cited 74 times

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The third‐order optical susceptibility of the Pt, Pb, and metal‐free tetrakis(cumylphenoxy)phthalocyanines was measured by degenerate four‐wave mixing at 1.064 μm, far from strong absorption bands. Metal substitution strongly enhances the off‐resonant χ(3). The χ(3)xxxx for Pt‐phthalocyanine (2×10−10 esu) and Pb phthalocyanine (2×10−11esu) is about 45 times and 5 times that of the metal‐free form (4×10−12 esu), respectively.
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42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
78.20.-e Optical properties of bulk materials and thin films
78.66.Qn Polymers; organic compounds

Centrifugal mass separation in rotating plasmas produced by a coaxial plasma gun

T. Ikehata, M. Suzuki, T. Tanabe, and H. Mase

Appl. Phys. Lett. 55, 1289 (1989); http://dx.doi.org/10.1063/1.101635 (3 pages) | Cited 2 times

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Rotating Cu/Zn plasmas produced by a coaxial plasma gun have been applied to plasma centrifuge. A separation factor of up to 10 is measured over a radius of 4 cm when a current of 13 kA and an axial magnetic field of 2.5 kG are applied. Plasma parameters are: rotation frequency ω=1.1×106 rad/s, density n∼1015 cm−3, and ion temperature Ti=10 eV. The separation factor of 2 is attained even in the plasma core where the density is higher than one‐half of the peak value. This is attributed to the fact that a strong centrifugal force forms a hollow density profile which gives the density peak at a radius of 2 cm.
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28.60.+s Isotope separation and enrichment
52.75.Di Ion and plasma propulsion
52.50.Dg Plasma sources
52.80.Mg Arcs; sparks; lightning; atmospheric electricity

Observation of CH2 radical and comparison with CH3 radical in a rf methane discharge

H. Kojima, H. Toyoda, and H. Sugai

Appl. Phys. Lett. 55, 1292 (1989); http://dx.doi.org/10.1063/1.101636 (3 pages) | Cited 48 times

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Methylene radical (CH2) in a rf methane discharge was detected using threshold ionization mass spectrometry. The absolute density of CH2 radical (∼109 cm−3) for the discharge in 10 mTorr CH4 with 10 W rf power was two orders of magnitude less than the density of methyl radical (CH3). The CH2 density in the afterglow of a pulsed rf discharge turned out to decay on a time scale (≤10 ms) much shorter than the decay time of CH3 radical (∼100 ms). The observed rapid loss of CH2 radical was attributed to a large sticking coefficient and the resultant surface loss, in addition to gas phase losses due to the CH2 reactions with CH3 and CH4.
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52.70.Nc Particle measurements
52.80.Pi High-frequency and RF discharges
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
82.30.Cf Atom and radical reactions; chain reactions; molecule-molecule reactions

Ion beam mixing in Ag‐Pd alloys

J. L. Klatt, R. S. Averback, and David Peak

Appl. Phys. Lett. 55, 1295 (1989); http://dx.doi.org/10.1063/1.101637 (3 pages) | Cited 24 times

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Ion beam mixing during 750 keV Kr+ irradiation at 80 K was measured on a series of Ag‐Pd alloys using Au marker atoms. The mixing in pure Ag was the greatest and it decreased monotonically with increasing Pd content, being a factor of 10 higher in pure Ag than in pure Pd. This large difference in mixing cannot be explained by the difference in cohesion energy between Ag and Pd in the thermodynamic model of ion beam mixing proposed by Johnson et al. [W. L. Johnson, Y. T. Cheng, M. Van Rossum, and M‐A. Nicolet, Nucl. Instrum. Methods B 7/8, 657 (1985)]. An alternative model based on local melting in the cascade is shown to account for the ion beam mixing results in Ag and Pd.
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61.80.Jh Ion radiation effects
66.30.J- Diffusion of impurities
61.72.up Other materials

Temperature flashes in reentrant superconductors and compounds with metal‐insulator transition

A. I. Buzdin, V. V. Moshchalkov, and A. Y. Simonov

Appl. Phys. Lett. 55, 1298 (1989); http://dx.doi.org/10.1063/1.101895 (2 pages)

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Local heating in reentrant superconductors and compounds with the metal‐insulator transition along the track of the high‐energy particle is studied. Numerical calculations of temperature flashes in VO2 are carried out. Possible applications of this phenomenon in the detectors of the particles are discussed.
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74.25.Ha Magnetic properties including vortex structures and related phenomena
74.70.Dd Ternary, quaternary, and multinary compounds (including Chevrel phases, borocarbides, etc.)
71.30.+h Metal-insulator transitions and other electronic transitions
29.40.-n Radiation detectors
81.40.Rs Electrical and magnetic properties related to treatment conditions

Effect of stacking sequence on valence bands in Ga/As/Ge (001) monolayer superlattices

T. Saito and T. Ikoma

Appl. Phys. Lett. 55, 1300 (1989); http://dx.doi.org/10.1063/1.101638 (3 pages) | Cited 1 time

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Valence bands of Ga/As/Ge (001) monolayer superlattices (MLSLs) are calculated by Harrison’s tight‐binding method. The MLSLs have two possible types of growth cycles: a (Ga,As,Ge,Ga,As,Ge) cycle for an antiphase type (AP type) and a (Ga,As,Ge,As,Ga,Ge) cycle for a normal phase type (NP type). Cations and anions in the AP type occupy ‘‘antisites’’ of the zinc blende structure while those in the NP type occupy only ‘‘normal sites.’’ The two types have distinct features of the valence bands concerning degeneracy of the bands at the zone boundary, splitting of the valence‐band maximum due to the tetragonal symmetry, and valence‐band discontinuity in a (bulk Ge)/(the MLSL) junction.
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73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

Structure of CdTe‐Cd1−xMnxTe multiple quantum wells grown on (001) InSb substrates by molecular beam epitaxy

G. M. Williams, A. G. Cullis, C. R. Whitehouse, D. E. Ashenford, and B. Lunn

Appl. Phys. Lett. 55, 1303 (1989); http://dx.doi.org/10.1063/1.101639 (3 pages) | Cited 13 times

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Molecular beam epitaxy has been used to prepare multiple quantum well structures of CdTe/Cd1−xMnxTe on (001) InSb substrates. The growth of such a system on InSb allows the use of particularly low growth temperatures, hence minimizing interdiffusion effects. This study presents the first transmission electron microscope investigation of this multilayer system grown on InSb. The work clearly demonstrates that multiple quantum wells of high structural quality can be grown reproducibly over a wide range of layer thicknesses. The importance of efficient substrate surface cleaning prior to growth is demonstrated. In order to grow high structural quality multilayers, the choice of buffer layer is also important and a possible explanation for this observation is given.
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68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.-a Thin film structure and morphology

Study of Si/SiO2 interface by transverse acoustoelectric voltage measurements

A. Abbate and F. Palma

Appl. Phys. Lett. 55, 1306 (1989); http://dx.doi.org/10.1063/1.102472 (3 pages) | Cited 2 times

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Improved acoustoelectric measurements allow a precise determination of surface trap level distribution in the silicon band gap at the Si/SiO2 interface. Two kinds of experiments are presented: the effect of a uniaxial compression and the effect of HCl annealing are monitored by transverse acoustoelectric voltage versus voltage measurements. Results indicate the presence of three energy trap levels, located at −0.2, −0.1, and +0.03 eV from the band midgap. A precise correspondence was found between the experimental results and a theory of the Si/SiO2 interface electronic state presented in the literature. This correspondence allows one to relate the first trap level to the presence of Na+ charges in the oxide while the last two levels can be related to Si dangling bonds.
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73.20.At Surface states, band structure, electron density of states
73.20.Hb Impurity and defect levels; energy states of adsorbed species
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
73.50.Rb Acoustoelectric and magnetoacoustic effects

X‐ray rocking curves from (100) and (111) CdTe grown on (100) GaAs by hot wall epitaxy

K. Lischka, E. J. Fantner, T. W. Ryan, and H. Sitter

Appl. Phys. Lett. 55, 1309 (1989); http://dx.doi.org/10.1063/1.101640 (3 pages) | Cited 11 times

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X‐ray rocking curves of (100) and (111) oriented CdTe epilayers grown by hot wall epitaxy on (100) GaAs substrates have been measured. Our results indicate that the number of extended defects increases with thickness in (111) CdTe epilayers but decreases with thickness in (100) CdTe epilayers. The distortion of the GaAs surface induced by the CdTe epilayer is determined from comparative measurements of the rocking curve of the covered and uncovered GaAs substrate.
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81.15.Kk Vapor phase epitaxy; growth from vapor phase
61.05.C- X-ray diffraction and scattering
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
68.55.-a Thin film structure and morphology

Direct writing in Si with a scanning tunneling microscope

E. J. van Loenen, D. Dijkkamp, A. J. Hoeven, J. M. Lenssinck, and J. Dieleman

Appl. Phys. Lett. 55, 1312 (1989); http://dx.doi.org/10.1063/1.101641 (3 pages) | Cited 40 times

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Using the W tip of a scanning tunneling microscope, indentations with diameters of 2–10 nm have been made directly in Si (110) and Si (001) surfaces. It is possible to create and image (‘‘write and read’’) arbitrary lines and bit patterns reproducibly with a single tip, without degrading its sharpness. The method does not require ideally flat surfaces and the indentations, when made in Si and kept in ultrahigh vacuum, are stable in time.
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81.65.-b Surface treatments
07.79.Cz Scanning tunneling microscopes
61.05.-a Techniques for structure determination
07.78.+s Electron, positron, and ion microscopes; electron diffractometers
68.35.B- Structure of clean surfaces (and surface reconstruction)

Damage formed by ion implantation in silicon evaluated by displaced atom density and thermal wave signal

Tohru Hara, Shuya Takahashi, Hiroyuki Hagiwara, Jun Hiyoshi, W. Lee Smith, C. Welles, S. K. Hahn, L. Larson, and C. C. D. Wong

Appl. Phys. Lett. 55, 1315 (1989); http://dx.doi.org/10.1063/1.102473 (3 pages) | Cited 2 times

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Damage formed by BF+2 and As+ implantations in Si was evaluated quantitatively. The density of displaced atoms (Dda) was determined from 1.5 MeV He+ Rutherford backscattering spectrometery. Dda increased from 4.7×1016 to 1.6×1017 cm−2 with the dose increased from 6.0×1013 to 1.3×1014 cm−2. However, Dda saturates at around 4×1017 cm−2 for all doses above 5×1014 cm−2. The thermal wave signal intensity shows the same dose dependence as Dda. This result shows that thermal wave signal intensity has a close relation with the density of displaced atoms formed by ion implantation. Therefore, quantitative damage monitorings can be achieved by thermal wave intensity measurements. Also, the variation of thermal wave signal intensity with ion implant energy was studied.
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61.80.Jh Ion radiation effects
68.35.Dv Composition, segregation; defects and impurities
61.72.uf Ge and Si
73.30.+y Surface double layers, Schottky barriers, and work functions

Charge trapping characteristics of the interface states in an AlN/GaAs metal‐insulator‐semiconductor structure

Y. Mochizuki, M. Mizuta, S. Fujieda, and Y. Matsumoto

Appl. Phys. Lett. 55, 1318 (1989); http://dx.doi.org/10.1063/1.101642 (3 pages) | Cited 6 times

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Charge trapping properties of the interface states present at the AlN/n‐GaAs interfaces are investigated through high‐frequency capacitance transients. They change their behavior from electron to hole traps with the excursion of surface Fermi level towards the valence band. This observation indicates that it is ionization of the states near midgap, not the hole inversion, which blocks the downward excursion of surface potential in GaAs/ insulator systems. It is also found that these states are well defined in terms of having a single capture cross section within the energy range probed, and furthermore, they are spatially localized at the interface.
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73.20.Hb Impurity and defect levels; energy states of adsorbed species
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems

Orientation‐dependent metalorganic vapor phase epitaxy regrowth on GaInAsP/InP laser structures

F. Fidorra, P. Harde, H. Venghaus, and D. Grützmacher

Appl. Phys. Lett. 55, 1321 (1989); http://dx.doi.org/10.1063/1.101643 (3 pages) | Cited 2 times

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GaInAsP/InP lasers made by low‐pressure metalorganic vapor phase epitaxy regrowth on patterned surfaces exhibit yield and performance dependent on laser stripe orientation. Structures with stripes parallel to the 〈011〉 and 〈011〉 directions are investigated by secondary ion mass spectroscopy (SIMS). Three‐dimensional SIMS profiles taken with high horizontal resolution using the checkerboard matrix gate technique yield unexpected results for structures with stripes parallel to the 〈011〉 direction: phosphorus is found in the nominal GaInAs layer, its distribution is strongly inhomogeneous. Zn diffused into the GaInAs layer exhibits also pronounced spatial variations. Unwanted P outdiffusion and anomalous Zn diffusion are attributed to reduced crystalline perfection of the InP above 〈011〉 oriented laser stripes.
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42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.55.Px Semiconductor lasers; laser diodes
81.15.Kk Vapor phase epitaxy; growth from vapor phase
66.30.J- Diffusion of impurities

Electric field response of a semiconductor superlattice optical mirror from electroreflectance spectra

I. J. Fritz, P. L. Gourley, and T. J. Drummond

Appl. Phys. Lett. 55, 1324 (1989); http://dx.doi.org/10.1063/1.101644 (3 pages) | Cited 5 times

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We report low‐field electroreflectance (ER) spectra of an all‐semiconductor multilayer optical mirror structure. The structure, consisting of alternating blocks of AlAs/Al0.5Ga0.5 As and Al0.5Ga0.5As/GaAs multiple quantum well layers, was grown by molecular beam epitaxy without wafer rotation. Thickness variations across the wafer produce a position‐dependent reflectance spectrum. The observed line shape of the band‐edge exciton depends on its wavelength position relative to the mirror spectrum and cannot be explained by ordinary ER theory, due to the rapidly varying background mirror reflectance. Computer simulations, using the matrix method to calculate the reflectance for different layer thicknesses and exciton energies, agree qualitatively with the data. A strong enhancement in ER response is predicted near the minima in the mirror spectrum. This enhancement is important in electo‐optic reflectance modulators.
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78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
78.20.Jq Electro-optical effects
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.61.Ey III-V semiconductors

Observation of quantum size effect in the resistivity of thin, gray tin epilayers

Li‐Wei Tu, George K. Wong, and John B. Ketterson

Appl. Phys. Lett. 55, 1327 (1989); http://dx.doi.org/10.1063/1.101645 (3 pages) | Cited 15 times

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Thin, gray tin films, with thicknesses from 50 to 375 Å, have been grown on (001) CdTe wafers by the molecular beam epitaxy technique. Resistivity measurements in the intrinsic region show a thickness‐dependent band gap. Quantum size effect theory using a square well potential has been used to interpret the experimental data.
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73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
73.61.At Metal and metallic alloys
73.20.At Surface states, band structure, electron density of states
73.20.Fz Weak or Anderson localization

Charge confinement in heterojunction acoustic charge transport devices

G. A. Peterson, B. J. McCartin, W. J. Tanski, and R. E. LaBarre

Appl. Phys. Lett. 55, 1330 (1989); http://dx.doi.org/10.1063/1.101646 (3 pages)

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An equilibrium model is developed for charge confinement in heterojunction acoustic charge transport (HACT) devices. The Poisson–Boltzmann equation is solved for the self‐consistent potential and packet charge distribution in a surface acoustic wave (SAW) superimposed on a (Al,Ga)As/GaAs hetrostructure. Numerical results are presented for the charge capacity of a 275 MHz HACT configuration. For a 1 V SAW potential, the charge capacity is limited by the heterojunction well depth rather than by space‐charge lowering of the SAW barrier.
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85.30.De Semiconductor-device characterization, design, and modeling
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
72.20.Fr Low-field transport and mobility; piezoresistance
43.35.Pt Surface waves in solids and liquids

Initial stages of heteroepitaxial growth of InAs on Si (100)

Doeke J. Oostra, Russell V. Smilgys, and Stephen R. Leone

Appl. Phys. Lett. 55, 1333 (1989); http://dx.doi.org/10.1063/1.101647 (3 pages) | Cited 9 times

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Adsorption and desorption of In on partially and fully As‐terminated Si(100) are investigated by laser‐induced fluorescence detection and Auger electron spectroscopy using the methods of temperature programmed desorption and isothermal desorption. Desorption measurements show that As is bound to the surface more strongly than In. For In, a 2/3 order kinetic desorption mechanism is observed. This and Si Auger intensity attenuation measurements indicate a strong tendency for In to form three‐dimensional islands on the As‐terminated surface. The activation energy for In diffusion from the islands ranges from 1.5 to 1.9 eV, depending on the As coverage. The results have important implications for growth of InAs on Si(100).
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.35.Fx Diffusion; interface formation
68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics

Uniaxial stress dependence of current‐voltage characteristics in GaAs‐AlxGa1−xAs‐GaAs heterojunction barriers

S. S. Lu, K. Lee, M. I. Nathan, M. Heiblum, and S. L. Wright

Appl. Phys. Lett. 55, 1336 (1989); http://dx.doi.org/10.1063/1.101648 (3 pages) | Cited 8 times

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Current‐voltage characteristics of nGaAs‐iAlxGa1−xAs‐nGaAs heterojunction barriers grown on (100) substrates have been measured under uniaxial stress along 〈100〉 at 77 K. The results show that thermionic emission current through longitudinal X valleys becomes dominant over Fowler–Nordheim tunneling current through Γ or transverse X valleys, as stress increases. From the stress‐dependent thermionic emission current the rate of change with stress of the band‐edge energy difference between Γ in GaAs and longitudinal X in AlGaAs is deduced to be 14±2 meV/kbar, which leads to an X‐valley shear deformation potential of 9.6±1.8 eV.
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73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.40.Gk Tunneling
79.40.+z Thermionic emission
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems

Band‐edge discontinuities of strained‐layer InxGa1−xAs/GaAs heterojunctions and quantum wells

S. Niki, C. L. Lin, W. S. C. Chang, and H. H. Wieder

Appl. Phys. Lett. 55, 1339 (1989); http://dx.doi.org/10.1063/1.101649 (3 pages) | Cited 62 times

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The conduction‐band discontinuity (ΔEc ) and the band‐gap offset (ΔEgh) of InxGa1−xAs/GaAs multiple quantum wells grown on GaAs substrates by molecular beam epitaxy are investigated for 0<x<0.3. The band gap of strained InxGa1−xAs , determined from the excitonic transition of room‐temperature transmission spectra, is found to be linearly dependent on x and is in good agreement with the calculated values. The band‐gap offset is found to be ΔEgh =1.15x eV. The conduction‐band offset, compiled from published data, is ΔEc =0.75x eV, and thus (ΔEc /ΔEgh)=0.65 independent of x.
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73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

Carbon and zinc delta doping for Schottky barrier enhancement on n‐type GaAs

S. J. Pearton, F. Ren, C. R. Abernathy, W. S. Hobson, S. N. G. Chu, and J. Kovalchick

Appl. Phys. Lett. 55, 1342 (1989); http://dx.doi.org/10.1063/1.101650 (3 pages) | Cited 15 times

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The growth of thin (50–100 Å), C or Zn δ‐doped layers on n‐type GaAs is shown to yield large enhancements in the effective Schottky barrier height (ΦB) of TiPtAu contacts subsequently deposited on the material. The incorporation of a single C δ‐doped layer (p=1.5×1020 cm−3, 50 Å wide) within 100 Å of the surface leads to a barrier height of 0.93 eV, a significant increase over the value for a control sample (0.76 eV). The use of two sequential δ‐doped layers leads to an apparent barrier height in excess of the GaAs band gap (ΦB=1.67 eV). This appears to be consistent with the predictions of a unified defect model. Zinc δ doping (p∼3×1018 cm−3) in a similar fashion produces barrier heights of 0.81 eV for one spike and 0.95 eV for two spikes.
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73.30.+y Surface double layers, Schottky barriers, and work functions
73.40.Ns Metal-nonmetal contacts
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
73.61.Ey III-V semiconductors
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