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  • 1
    Electronic Resource
    Electronic Resource
    Exciton luminescence in Si1−xGex/Si heterostructures grown by molecular beam epitaxy (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2790-2805 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Coherent Si1−xGex alloys and multilayers synthesized by molecular beam epitaxy (MBE) on Si(100) substrates have been characterized by low-temperature photoluminescence (PL) spectroscopy and transmission electron microscopy (TEM). Phonon-resolved transitions originating from excitons bound to shallow impurities were observed in addition to a broad band of intense luminescence. The broad PL band was predominant when the alloy layer thickness was greater than 40–100 A(ring), depending on x and the strain energy density. The strength of the broad PL band was correlated with the areal density (up to ∼109 cm−2) of strain perturbations (local lattice dilation ∼15 A(ring) in diameter) observed in plan-view TEM. Thinner alloy layers exhibited phonon-resolved PL spectra, similar to bulk material, but shifted in energy due to strain and hole quantum confinement. Photoluminescence excitation spectroscopy, external quantum efficiency, time-resolved PL decay, together with the power and temperature dependence of luminescence intensity, have been used to characterize Si1−xGex/Si heterostructures exhibiting both types of PL spectra. The role of MBE growth parameters in determining optical properties was investigated by changing the quantum well thickness and growth temperature. The transition from phonon-resolved, near-band-gap luminescence in thin layers to the broad PL band typical of thick layers is discussed in terms of a strain energy balance model which predicts a "transition thickness'' which decreases with increase in x.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354628
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  • 2
    Electronic Resource
    Electronic Resource
    Photoluminescence from Si1−xGex strained layers grown by atmospheric pressure chemical vapor deposition (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 6201-6203 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Low temperature photoluminescence due to the self-annihilation of bound excitons has been observed in Si1−xGex strained layers grown using atmospheric pressure chemical vapor deposition. Samples were grown at temperatures near 1000 °C with growth rates up to 1000 nm per minute allowing short growth times, thus preventing extensive interdiffusion at layer interfaces. Well-resolved, bulk-like photoluminescence spectra with narrow no phonon linewidths were observed from strained SiGe material indicating it to be of suitable electronic quality. For a sample consisting of 120 nm of Si0.92Ge0.08 capped with 90 nm of Si on a Si(100) substrate, the photoluminescence spectrum exhibited Si1−xGex bound exciton lines with resolved no phonon and transverse optic phonon components.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350433
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  • 3
    Electronic Resource
    Electronic Resource
    A field-assisted emission model of interface states in heterostructure devices (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 7382-7386 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present a physical model to study the interface states in p-n heterostructures at different ambient temperatures. Field-assisted emission of such states is considered as the source for the linear increase in charge concentration at the p-n interface with the applied reverse voltage. The high frequency capacitance-voltage technique is used to study the charging and discharging of interface states in an MBE-made sample at different temperatures and different biases. The experimental results show good agreement with the prediction of our model. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360725
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  • 4
    Electronic Resource
    Electronic Resource
    Photoluminescence from Si(001) films doped with 100–1000 eV B+ ions during deposition by molecular beam epitaxy (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 4623-4631 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Temperature-dependent photoluminescence (PL) measurements have been used to characterize 5-μm-thick Si(001) layers doped with low-energy 11B+ ions (EB+=100, 500, and 1000 eV) during molecular beam epitaxy (MBE) at growth temperatures Ts=500, 650, and 800 °C. Films deposited at 800 °C with EB+=100 and 500 eV exhibited spectra comparable to bulk Si with narrow intense B1TO exciton recombination peaks together with multiple-exciton B2TO and B3TO peaks as well as free-exciton FETO, BTO+Or1, BTO(2h), B1TA, and B1LO peaks showing that the films are of very high quality. The overall luminescence intensity was found to decrease with decreasing Ts and increasing EB+. PL spectra from films grown at the lowest temperature, Ts=500 °C, were quite different in appearance with very weak bound-exciton peaks and additional features, I3 and I3TA, near 1040 meV due to residual ion-induced damage which increased in intensity with increasing EB+. Compared to As+ ion doping, lower ion energies and/or higher growth temperatures are required to avoid residual ion-induced damage in B+ ion-doped MBE Si(001). Post-annealing experiments showed no detectable residual ion-induced lattice damage in B+-doped, Ts=500 °C, films after 15 min at 800 °C. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359428
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  • 5
    Electronic Resource
    Electronic Resource
    Metal-insulator-semiconductor capacitors on cleaved GaAs(110) (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 8192-8194 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Metal-insulator-semiconductor capacitors were fabricated on cleaved n-GaAs (110) facets using remote plasma-deposited silicon nitride as gate insulators. The interface properties of the capacitors made on this surface were analyzed by capacitance-voltage (C-V) measurements. X-ray photoemission spectroscopy was also used to investigate the chemical structure of the interface. Prior to the insulator deposition, the cleaved facets were processed with different surface treatments including HF etch of native oxide, passivation with an ammonium sulfide solution, passivation with hydrogen polysulfide, and passivation with a silicon interface control layer. It was found that while the passivation procedures with the sulfur compounds did improve the C-V data when compared with the HF oxide etch, the silicon interface control layer technique led to the best C-V results. By comparing the quasistatic and high-frequency (1 MHz) C-V data, it was found that the minimum interface state density of the fabricated capacitors was about 1012 eV−1 cm−2. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.358429
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  • 6
    Electronic Resource
    Electronic Resource
    Electroluminescence and photoluminescence from Si1−xGex alloys (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 957-958 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Electroluminescence has been observed from Si1−xGex/Si p-n heterostructures grown by molecular beam epitaxy and fabricated into mesa diodes. The luminescence from each sample was observed at temperatures up to 80 K with diodes forward biased at current densities up to 50 A/cm2. For x=0.18 and x=0.25, broad (∼80 meV) electroluminescence peaks were observed at 890 and 860 meV, respectively. These energies as well as the peak shapes and quantum efficiencies (∼1%) were the same as those from corresponding photoluminescence spectra.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.104454
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  • 7
    Electronic Resource
    Electronic Resource
    Photoluminescence studies of Si (100) doped with low-energy (100–1000 eV) B+ ions during molecular beam epitaxy (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 265-267 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Temperature-dependent photoluminescence (PL) measurements have been used to characterize 5-μm-thick Si(100) epitaxial layers doped in situ during molecular beam epitaxial growth with low-energy (100, 500, and 1000 eV) 11 B+ ions at growth temperatures of 500, 650, and 800 °C. Moderate doping (NB ∼1017 cm−3) yielded PL features comprised of both sharp and broad peaks in the boron bound exciton (B-BE) region. At 4.2 K a broad B-BE feature near 1086 meV dominated, although the sharp transverse optical phonon-assisted B-BE peak (B1TO ) at 1092.5 meV was resolvable for NB〈1017 cm−3. Increasing the PL sample temperature above 4.2 K caused a rapid decay of the broad B-BE peak intensity, thus permitting comparison of B1TO intensity for a range of ion energies and growth temperatures. At 10 K, a bulk-like spectrum containing a sharp B1TO peak with weaker multiexciton peaks B2TO and B3TO was observed for the film growth at the highest temperature and lowest ion energy (800 °C and 100 eV). However, the intensity of the B1TO peak decreased with decreasing growth temperature (constant ion energy) and with increasing ion energy (constant growth temperature). Samples grown at the lowest temperature (500 °C) displayed very different PL spectra with much weaker line emission, a rising PL background, and additional lines near 1040 meV due to ion-induced residual lattice defects. Quenching of B1TO and the other sharp B-BE peaks was accompanied by an increase in the N1 peak at 745.7 meV.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102804
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  • 8
    Electronic Resource
    Electronic Resource
    Intense photoluminescence between 1.3 and 1.8 μm from strained Si1−xGex alloys (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 1037-1039 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Intense photoluminescence (PL) from strained, epitaxial Si1−xGex alloys grown by molecular beam epitaxy is reported with measured internal quantum efficiencies up to 31% from random alloy layers, single buried strained layers, and multiple quantum wells. Samples deposited at ∼400 °C exhibited low PL intensity, whereas annealing at ∼600 °C enhanced the intensity by as much as two orders of magnitude. This anneal treatment was found to be optimal for removal of grown-in defect complexes without creating a significant density of misfit dislocations. PL peak energies at 4.2 K varied from 620 to 990 meV for Ge fractions from 0.53 to 0.06, respectively. Efficient PL was due to exciton accumulation in the strained Si1−xGex layers of single and multiple quantum wells, where the band gap was locally reduced. Optical transitions associated with the PL occurred without phonon assistance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.103558
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  • 9
    Electronic Resource
    Electronic Resource
    Photoluminescence studies of Si (100) doped with low-energy (≤1000 eV) As+ ions during molecular beam epitaxy (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 1525-1527 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Low-temperature (4.2K) photoluminescence (PL) has been used to characterize Si(100) films doped with EAs =200, 500, and 1000 eV 75 As+ ions during growth by molecular beam epitaxy on n+ Sb-doped substrates at temperatures Ts between 500 and 800 °C. Sharp no-phonon, transverse-optical, and transverse-acoustic phonon-assisted bound-exciton (BE) Peaks associated with As dopant species, together with broader, weaker, Sb-related BE peaks, were the dominant PL features obtained from 5-μm-thick layers. No peaks ascribable to residual ion-induced damage were observed in films grown at 650 °C with EAs =200 eV or Ts =800 °C with EAs =200, 500, and 1000 eV. However, reducing the film growth temperature to 500 °C with Eas =200 eV gave rise to a strong ion-damage PL peak at 1039.7 meV. Furthermore, both undoped and As ion-doped films grown at 500 °C exhibited a gradual increase in the PL background below 890 meV which we believe was due to quenched-in point defects. Complementary deep level transient spectroscopy measurements showed electron trap states (concentrations(approximately-equal-to)1014 cm−3) at energies of 0.06 an d-0.52 eV below the conduction-band edge for films grown at 500 °C with EAs =200 eV. No traps were observed in the ion-doped Ts=650 and 800 °C samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102303
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  • 10
    Electronic Resource
    Electronic Resource
    Electrical properties of Si films doped with 200-eV In+ ions during growth by molecular-beam epitaxy (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 1189-1197 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A single-grid ultra-high-vacuum-compatible ion source was used to provide accelerated In+-dopant beams during Si(100) growth by molecular-beam epitaxy. Indium incorporation probabilities σ, determined by secondary ion mass spectrometry, in films grown at Ts=800 °C were too low to be measured for thermal In (σIn was 〈3×10−5 at Ts〉550 °C) . However, for accelerated In+ doping, σIn+ at 800 °C ranged from 0.03 to ∼1 for In+ acceleration energies EIn+ between 50 and 400 eV. Temperature-dependent Hall-effect and resistivity measurements were carried out on In+-doped Si films grown at Ts =800 °C with EIn+=200 eV . Indium was incorporated substitutionally into electrically active sites over a concentration ranging from 2×1015−2×1018 cm−3, which extends well above reported equilibrium solid-solubility limits. The acceptor-level ionization energy was 156 meV, consistent with previously published results for In-doped bulk Si. Room-temperature hole mobilities μ were in good agreement with the best reported data for B-doped bulk Si and were higher than previously reported values for annealed In-implanted Si. Temperature-dependent (77–400 K) mobilities μ(T) were well described by theoretical calculations, with no adjustable parameters, including lattice, ionized-impurity, neutral-impurity, and hole-hole scattering. Lattice scattering was found to dominate, although ionized-impurity scattering was still significant, at temperatures above ∼150 K where μ varied approximately as T−2.2 . Neutral-impurity scattering dominated at lower temperatures. Plan-view and cross-sectional transmission electron microscopy observations showed no indications of dislocations or other extended defects. Considering the entire set of results, there was no evidence of residual ion-bombardment-induced lattice damage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343062
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