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24 Jun 2002

Volume 80, Issue 25, pp. 4687-4873

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Characterization of S centers generated by thermal degradation in SiO2 on (100)Si

A. Stesmans, B. Nouwen, D. Pierreux, and V. V. Afanas’ev

Appl. Phys. Lett. 80, 4753 (2002); http://dx.doi.org/10.1063/1.1481539 (3 pages) | Cited 1 time

Online Publication Date: 17 June 2002

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The structural degradation of thermal SiO2 on (100)Si under isochronal vacuum annealing in the range Tan = 950 °C–1250 °C was monitored by electron spin resonance (ESR) in terms of point defect creation, including Eγ′, Eδ′, EX and the elusive predominant degradation-center S. Depth profiling after heating at 1200 °C shows that the S centers predominantly reside near the oxide borders, generally in anticorrelation with the Eγ′ distribution. The resulting anisotropic demagnetization effect has enabled inference of the S center susceptibility. As to the nature of the S center, an observed weak hyperfine structure may comply with the S center being of the type SinO3−n ≡ Si⋅ either the single n = 1 or a mix of both the n = 1,2 variants. © 2002 American Institute of Physics.
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76.30.Mi Color centers and other defects
61.72.J- Point defects and defect clusters
61.72.Cc Kinetics of defect formation and annealing
71.55.Ht Other nonmetals
75.20.Ck Nonmetals
73.20.Hb Impurity and defect levels; energy states of adsorbed species

Interface properties of SiO2/n-GaN metal–insulator–semiconductor structures

Yoshitaka Nakano and Takashi Jimbo

Appl. Phys. Lett. 80, 4756 (2002); http://dx.doi.org/10.1063/1.1486266 (3 pages) | Cited 19 times

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Electrical characterization of SiO2/n-GaN metal–insulator–semiconductor structures fabricated on sapphire substrates was performed by using high-frequency pulsed capacitance–voltage and capacitance-transient techniques. Fast and slow capacitance transients are clearly seen after applying reverse voltages, reflecting thermal emissions of carriers from the SiO2/GaN interface. The temperature dependence of the capacitance–voltage characteristics shows capacitance saturation in deep depletion (>15 V), which is probably associated with the slow capacitance transient. Deep-level transient spectroscopic measurements reveal two interface traps with activation energies of 0.71 and ∼0.76 eV from the conduction band, corresponding to the fast and slow capacitance transients, respectively. Therefore, the observed capacitance saturation may be due to Fermi-level pinning induced by the latter interface trap. © 2002 American Institute of Physics.
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73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
68.35.Ct Interface structure and roughness
73.20.Hb Impurity and defect levels; energy states of adsorbed species
73.20.At Surface states, band structure, electron density of states
73.50.Dn Low-field transport and mobility; piezoresistance
73.61.Ey III-V semiconductors
73.61.Ng Insulators

Monte Carlo calculation of electronic noise under high-order harmonic generation

P. Shiktorov, E. Starikov, V. Gružinskis, L. Reggiani, L. Varani, and J. C. Vaissière

Appl. Phys. Lett. 80, 4759 (2002); http://dx.doi.org/10.1063/1.1488694 (3 pages) | Cited 8 times

Online Publication Date: 17 June 2002

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The time and frequency behavior of hot-carrier velocity fluctuations in bulk semiconductors subjected to strong periodic electric fields is analyzed by using two complementary approaches based on the correlation function and the finite Fourier transform. Monte Carlo calculations performed for GaAs, InP, and InN show that semiconductor materials with a high value of the threshold field for the Gunn effect are characterized by a high value of the signal-to-noise ratio under high-order harmonics generation and, hence, they are promising materials for microwave generation in the terahertz frequency range by high-order harmonic extraction. © 2002 American Institute of Physics.
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72.70.+m Noise processes and phenomena
72.20.Ht High-field and nonlinear effects
72.30.+q High-frequency effects; plasma effects
72.80.Ey III-V and II-VI semiconductors

Changes in Al-related photoluminescence in 4H-SiC caused by hydrogenation

Yaroslav Koshka, Michael S. Mazzola, and William A. Draper

Appl. Phys. Lett. 80, 4762 (2002); http://dx.doi.org/10.1063/1.1489483 (3 pages) | Cited 5 times

Online Publication Date: 17 June 2002

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Both reduction of the intensity of aluminum-related photoluminescence after hydrogenation and the phenomenon of the optical quenching of the Al bound exciton (Al–BE) previously reported for hydrogenated 6H-SiC was observed now in the 4H-SiC polytype. Hydrogenation caused also a reduction of the nitrogen–aluminum donor-acceptor pair emission. Prolonged excitation of hydrogenated samples with above-band gap light resulted in additional quenching of the residual Al–BE photoluminescence. The quenching kinetics and some differences between the 6H and 4H polytypes are investigated. The observed phenomena are attributed to optically enhanced passivation of Al acceptors with hydrogen. © 2002 American Institute of Physics.
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78.66.Li Other semiconductors
78.55.Hx Other solid inorganic materials
71.35.Cc Intrinsic properties of excitons; optical absorption spectra

Influences of mask width, fill factor, HCl addition and C doping on wing tilts in the epitaxial laterally overgrown GaN films by hydride vapor phase epitaxy

F. Wang, R. Zhang, W. S. Tan, X. Q. Xiu, D. Q. Lu, S. L. Gu, B. Shen, Y. Shi, X. S. Wu, Y. D. Zheng, S. S. Jiang, and T. F. Kuech

Appl. Phys. Lett. 80, 4765 (2002); http://dx.doi.org/10.1063/1.1489099 (3 pages)

Online Publication Date: 17 June 2002

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Crystal tilts in the epitaxial lateral overgrown (ELO) GaN region over SiO2 mask by hydride vapor phase epitaxial away from the opening region were investigated by scanning electron microscope and the four-circle x-ray diffraction method. The increased mask width and ratio of stripe opening width to stripe period (fill factor) lead to increased wing tilts. The introduction of additional HCl and C3H8/H2 can decrease wing tilts and improve the ELO GaN surface morphologies significantly. Moreover, it has been observed that a high growth rate will bring more defects and large wing tilts into the GaN materials. © 2002 American Institute of Physics.
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68.55.-a Thin film structure and morphology
81.05.Ea III-V semiconductors
81.15.Kk Vapor phase epitaxy; growth from vapor phase
68.35.B- Structure of clean surfaces (and surface reconstruction)

Arsenic surface segregation during the molecular-beam epitaxial growth of GaAs embedded in wurtzite GaN

Hyonju Kim and T. G. Andersson

Appl. Phys. Lett. 80, 4768 (2002); http://dx.doi.org/10.1063/1.1489476 (3 pages) | Cited 5 times

Online Publication Date: 17 June 2002

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We report on the growth of a thin GaAs layer embedded in wurtzite GaN prepared on (0001) sapphire substrate by rf-plasma molecular-beam epitaxy. It was found that the As surface segregation during the growth of the GaN cap layer can be controlled by the growth parameters, i.e., the growth interruption and subsequent in situ annealing process implemented in this study. The arsenic profile of the cap layer was accurately evaluated using an empirical segregation model. The surface morphology was also investigated using atomic force microscopy. © 2002 American Institute of Physics.
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68.35.Dv Composition, segregation; defects and impurities
81.05.Ea III-V semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
61.72.Cc Kinetics of defect formation and annealing
68.37.Ps Atomic force microscopy (AFM)

Above-band gap two-photon absorption and its influence on ultrafast carrier dynamics in ZnTe and CdTe

M. Schall and P. Uhd Jepsen

Appl. Phys. Lett. 80, 4771 (2002); http://dx.doi.org/10.1063/1.1489480 (3 pages) | Cited 17 times

Online Publication Date: 17 June 2002

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We present measurements of transient carrier dynamics subsequent to intense above-band gap femtosecond excitation of the II–VI compounds ZnTe and CdTe, probed in the far infrared by transient terahertz time-domain spectroscopy. The intensity and temperature dependence of the carrier dynamics illuminates the role of two-photon absorption (TPA) of pump photons. At cold temperatures and high excitation intensities TPA results in a photoexcited carrier distribution which requires several picoseconds to thermalize. As a consequence, the dielectric function of the carrier distribution deviates strongly from the Drude model for as long as 20 ps after excitation. © 2002 American Institute of Physics.
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78.47.-p Spectroscopy of solid state dynamics
42.65.-k Nonlinear optics
72.80.Ey III-V and II-VI semiconductors
71.45.Gm Exchange, correlation, dielectric and magnetic response functions, plasmons
72.20.Fr Low-field transport and mobility; piezoresistance

Effect of vacancy and interstitial excess on the deactivation kinetics of As in Si

S. Solmi, M. Attari, and D. Nobili

Appl. Phys. Lett. 80, 4774 (2002); http://dx.doi.org/10.1063/1.1489719 (3 pages) | Cited 8 times

Online Publication Date: 17 June 2002

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The effect of a point defect excess, vacancies, or, respectively, interstitials, on the deactivation kinetics of As in Si was verified on silicon on insulator (SOI) substrates uniformly doped at concentrations in the range 1.8–7×1020 cm−3. SOI samples can provide more accurate carrier density measurements, moreover the buried oxide layer can prevent recombination of excess vacancies with the interstitials near the projected range. A dose of 5×1015 cm−2 Si+ ions was implanted at 100 keV to obtain interstitials supersaturation (Iex), while the same Si+ dose, at an energy of 2 MeV, was used to generate an excess of vacancies (Vex). These specimens were isothermally heated at different temperatures and their annealing behavior was compared with the one of reference undamaged samples of the same composition, but without point defect excess. Our results indicate that neither the excess of interstitials nor the one of vacancies appreciably affect the deactivation rate. Once the implantation damage has annealed out, the samples with point defect excess are found in the same situation of the reference ones, and the subsequent deactivation kinetics results coincident. © 2002 American Institute of Physics.
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72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
61.72.J- Point defects and defect clusters
72.80.Cw Elemental semiconductors
61.72.Cc Kinetics of defect formation and annealing
61.82.Fk Semiconductors
61.80.Jh Ion radiation effects

Deep-level defects in InGaAsN grown by molecular-beam epitaxy

R. J. Kaplar, S. A. Ringel, Steven R. Kurtz, J. F. Klem, and A. A. Allerman

Appl. Phys. Lett. 80, 4777 (2002); http://dx.doi.org/10.1063/1.1483912 (3 pages) | Cited 19 times

Online Publication Date: 17 June 2002

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Deep-level transient spectroscopy (DLTS) studies on both p-type unintentionally doped and n-type (Si-doped), 1.05 eV band gap InGaAsN grown by molecular-beam epitaxy are reported. Two majority-carrier hole traps were observed in p-type material, H3′ (0.38 eV) and H4′ (0.51 eV), and no evidence was found for the presence of minority-carrier electron traps. In n-type material, we observed a shallow distribution of electron levels, E1′, as well as a deep electron trap E4′ (0.56 eV) and a deep hole trap H5′ (0.71 eV). All DLTS peaks observed were broad and are thus consistent with continuous defect distributions and/or groups of closely spaced discrete energy levels in the band gap. Comparison of the spectra to previously reported spectra of metalorganic chemical vapor deposition-grown InGaAsN of the same composition revealed some similarities and some differences, suggesting that some of the observed deep levels are due to intrinsic physical sources, whereas others are specific to the growth technique used. © 2002 American Institute of Physics.
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71.55.Eq III-V semiconductors
68.55.-a Thin film structure and morphology
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Reliability of laser-activated low-temperature polycrystalline silicon thin-film transistors

Du.-Zen Peng, Ting-Chang Chang, Hsiao-Wen Zan, Tiao-Yuan Huang, Chun-Yen Chang, and Po-Tsun Liu

Appl. Phys. Lett. 80, 4780 (2002); http://dx.doi.org/10.1063/1.1489096 (3 pages) | Cited 5 times

Online Publication Date: 17 June 2002

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In this letter, the characteristics and reliability of laser-activated polycrystalline silicon thin-film transistors (poly-Si TFTs) have been investigated by stressing the devices under Vds = 12 V and Vgs = 15 V. In comparison with traditional furnace-activated poly-Si TFTs, the leakage current is relatively large for laser-activated poly-Si TFTs. Further, while the degradation rates of threshold voltage and subthreshold swing are comparable to those of traditional furnace-activated TFTs, the post-stress leakage and on/off current ratio for laser-activated poly-Si TFTs degrade much faster than those of furnace-activated counterparts. The laser activation modifies the grain structure between the drain and the channel region, and causes grain discontinuity extending from the drain to the channel region. As a result, an inferior reliability with extra trap state density and larger leakage current was observed in the laser-activated poly-Si TFTs. © 2002 American Institute of Physics.
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85.30.Tv Field effect devices
85.30.De Semiconductor-device characterization, design, and modeling
81.05.Cy Elemental semiconductors
42.62.-b Laser applications
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

Ge/Si quantum-dot metal–oxide–semiconductor field-effect transistor

A. I. Yakimov, A. V. Dvurechenskii, V. V. Kirienko, and A. I. Nikiforov

Appl. Phys. Lett. 80, 4783 (2002); http://dx.doi.org/10.1063/1.1488688 (3 pages) | Cited 8 times

Online Publication Date: 17 June 2002

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We report on the operation of Si metal–oxide–semiconductor field-effect transistor with an array of ∼ 103 10 nm diameter Ge self-assembled quantum dots embedded into the active channel. The drain current versus gate voltage characteristics show oscillations caused by Coulomb interaction of holes in the fourfold-degenerate excited state of the dots at T ⩽ 200 K. A dot charging energy of ∼ 43 meV (i.e., >kT = 26 meV at T = 300 K) and disorder energy of ∼ 20 meV are determined from the oscillation period and the temperature dependence study of current maxima, respectively. © 2002 American Institute of Physics.
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85.30.Tv Field effect devices
73.63.Kv Quantum dots
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
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