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20 Aug 2001

Volume 79, Issue 8, pp. 1073-1217

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Suppression of lateral fluctuations in CdSe-based quantum wells

E. Kurtz, M. Schmidt, M. Baldauf, S. Wachter, M. Grün, H. Kalt, C. Klingshirn, D. Litvinov, A. Rosenauer, and D. Gerthsen

Appl. Phys. Lett. 79, 1118 (2001); http://dx.doi.org/10.1063/1.1394172 (3 pages) | Cited 5 times

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We report a reduction of inhomogeneous broadening in CdSe-related quantum wells in ZnSe by employing a growth technique that uses a CdS-compound source instead of the standard Cd elemental source for molecular-beam epitaxy. Assisted by the low sticking coefficient of sulfur and possibly an exchange reaction between S and Se, only a small S contamination is observed. A comparison with standard layers reveals an increase in quality and homogeneity by a strong reduction of the photoluminescence (PL) linewidth. Samples obtained by our method show extremely little lateral confinement as indicated by a lack of sharp single dot emission lines in micro PL and the absence of the extensive redshift observed in temperature dependent PL of fluctuating well potentials. © 2001 American Institute of Physics.
Show PACS
81.07.St Quantum wells
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
78.55.Et II-VI semiconductors
81.05.Dz II-VI semiconductors
78.67.De Quantum wells

Observation of thermally activated conduction at a GaN–sapphire interface

C. Mavroidis, J. J. Harris, M. J. Kappers, N. Sharma, C. J. Humphreys, and E. J. Thrush

Appl. Phys. Lett. 79, 1121 (2001); http://dx.doi.org/10.1063/1.1395525 (3 pages) | Cited 15 times

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Temperature-dependent differential Hall measurements have been performed on an undoped GaN epitaxial layer grown by metalorganic chemical vapor deposition on a sapphire substrate. The resultant depth profile shows that, for this sample, the epitaxial material is mostly insulating, and that the observed thermally activated conduction arises from an interface region ⩽0.65 μm thick. Comparison with cross-sectional transmission electron microscope micrographs suggests that this conducting region is correlated to the highly defective three-dimensional growth region, while the two-dimensional growth mode beyond this thickness corresponds to the insulating portion with a lower dislocation density. Such behavior is consistent with the presence of an impurity band in a heavily doped interface region formed by oxygen outdiffusion from the substrate. © 2001 American Institute of Physics.
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73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
71.55.Eq III-V semiconductors
72.80.Ey III-V and II-VI semiconductors
73.61.Ey III-V semiconductors
72.20.My Galvanomagnetic and other magnetotransport effects
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
72.20.Pa Thermoelectric and thermomagnetic effects
73.50.Lw Thermoelectric effects
73.20.Hb Impurity and defect levels; energy states of adsorbed species

Bias stress in organic thin-film transistors and logic gates

S. J. Zilker, C. Detcheverry, E. Cantatore, and D. M. de Leeuw

Appl. Phys. Lett. 79, 1124 (2001); http://dx.doi.org/10.1063/1.1394718 (3 pages) | Cited 93 times

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Threshold voltage instabilities of all-organic thin-film transistors are investigated as a function of stress time and stress bias. The dominant effect is a positive threshold shift for negative gate bias stress which is explained by mobile ions drifting in the insulator when a gate field is applied. Trapping of charge carriers at the semiconductor–insulator interface plays only a minor role. Furthermore, we investigate the stress behavior of a basic logic element, an inverter. In comparison to a single transistor, we observe improved stability which arises from partial compensation of the parametric shifts during operation. © 2001 American Institute of Physics.
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85.30.Tv Field effect devices
84.30.Sk Pulse and digital circuits

Selenium-related luminescent centers in metalorganic chemical-vapor-phase deposition grown ZnSe epilayers on GaAs

X. B. Zhang, K. L. Ha, and S. K. Hark

Appl. Phys. Lett. 79, 1127 (2001); http://dx.doi.org/10.1063/1.1394949 (3 pages) | Cited 14 times

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ZnSe epilayers were grown on a (001) GaAs substrate by metalorganic chemical-vapor-phase deposition. An interruption of the Zn source (i.e., Se passivation) was purposely introduced during the growth. The optical properties of the epilayers grown were studied by photoluminescence (PL) spectroscopy. We show that Se passivation during the growth interruption introduces luminescent centers in the epilayers. Evidence of this assignment comes from the characteristic temperature and excitation wavelength dependence of the PL spectra, which are distinctly different from those of commonly observed deep-level emissions associated with the so-called self-activated centers. Moreover, the PL peak energy of the centers depends strongly on the coverage of Se: the longer the time or the higher the flow rate of the Se precursor used for the passivation, the lower the energy of its PL peak. The possible origin of this luminescence is discussed. © 2001 American Institute of Physics.
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78.55.Et II-VI semiconductors
78.66.Hf II-VI semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.15.Kk Vapor phase epitaxy; growth from vapor phase
81.05.Dz II-VI semiconductors

Measurement of piezoelectric field and tunneling times in strongly biased InGaN/GaN quantum wells

Y. D. Jho, J. S. Yahng, E. Oh, and D. S. Kim

Appl. Phys. Lett. 79, 1130 (2001); http://dx.doi.org/10.1063/1.1396315 (3 pages) | Cited 39 times

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We have measured both spectrum- and time-resolved photoluminescence (PL) of InGaN/GaN light-emitting diode structure as a function of an external bias. From spectrum-resolved PL, we observed regions of blueshift and redshift in peak PL energies. From the bias point at which redshift begins, which we attribute to the inversion of electric field due to full compensation of the piezoelectric field (PEF), we estimate PEF to be 2.1±0.2 MV/cm. From time-resolved PL, we found the carrier lifetimes to drastically decrease (2.5 ns–2 ps) with increasing reverse bias. We attribute this decrease to escape tunneling through tilted barriers. © 2001 American Institute of Physics.
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78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
73.21.Fg Quantum wells
78.67.De Quantum wells
78.47.-p Spectroscopy of solid state dynamics
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths

Predicted maximum mobility in bulk GaN

D. C. Look and J. R. Sizelove

Appl. Phys. Lett. 79, 1133 (2001); http://dx.doi.org/10.1063/1.1394954 (3 pages) | Cited 33 times

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A 300 K bulk (three-dimensional) mobility of 1245 cm2/V s has been measured in free-standing GaN. Temperature-dependent Hall-effect data on this particular sample are fitted to obtain unknown lattice-scattering parameters, as well as shallow donor (ND) and acceptor (NA) concentrations, which are ND = 6.7×1015 and NA = 1.7×1015 cm−3. Realistic values of the maximum mobility attainable in bulk GaN are then obtained by assuming two-orders-of-magnitude lower values of ND and NA, leading to a maximum 300 K mobility of 1350 cm2/V s, and a maximum 77 K mobility of 19 200 cm2/V s. © 2001 American Institute of Physics.
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72.80.Ey III-V and II-VI semiconductors
72.20.Fr Low-field transport and mobility; piezoresistance
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
72.20.My Galvanomagnetic and other magnetotransport effects

Long-wavelength HgCdTe negative luminescent devices

T. Ashley, N. T. Gordon, G. R. Nash, C. L. Jones, C. D. Maxey, and R. A. Catchpole

Appl. Phys. Lett. 79, 1136 (2001); http://dx.doi.org/10.1063/1.1395521 (3 pages) | Cited 12 times

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We have investigated the negative luminescent properties of a HgCdTe device, fabricated from a 1 mm diameter array of photodiodes having peak emission at a wavelength of 8.5 μm. This long-wavelength luminescence is of sufficient efficiency and area to be useful in device applications. © 2001 American Institute of Physics.
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85.60.Dw Photodiodes; phototransistors; photoresistors
85.60.Jb Light-emitting devices
78.66.Hf II-VI semiconductors
78.55.Et II-VI semiconductors

Effective enhancement of C54 TiSi2 phase formation with multi-thermal-shock processing at 600 °C

S. Li, Y. K. Lee, L. Zhang, W. Gao, and K. S. Lee

Appl. Phys. Lett. 79, 1139 (2001); http://dx.doi.org/10.1063/1.1382630 (3 pages)

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Enhancing C54 TiSi2 phase formation and reducing its formation temperature are two key issues in ultralarge-scale integration semiconductor industry. This work demonstrated that the formation of C54 TiSi2 phase can be effectively enhanced and the processing temperature can be reduced by 150–200 °C through multi-thermal-shock processing. The result shows that the resistivity of the TiSi2 compound decreased with increasing thermal shock frequency and consequently reached 15.90 μΩ cm at 600 °C. It is believed that the enhancement of C54 phase formation is due to the increase of internal energy of C49 crystals, which is caused by multi-thermal-shock processing. © 2001 American Institute of Physics.
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68.35.Fx Diffusion; interface formation
64.70.K- Solid-solid transitions
62.50.-p High-pressure effects in solids and liquids
85.40.Ls Metallization, contacts, interconnects; device isolation
73.61.At Metal and metallic alloys
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