In situ Raman measurements have been carried out on a thin bundle of single-walled carbon nanotub... more In situ Raman measurements have been carried out on a thin bundle of single-walled carbon nanotubes (SWNTs) in field effect transistor configuration at various gate voltages. Two excitation lasers with the photon energy of 1.96 eV and 2.41 eV, respectively, are selected to excite the Raman scattering modes of metallic and semiconducting SWNTs in the bundle, respectively. For the metallic SWNTs, the G- Raman mode is found to shift to higher frequencies and narrow down its line shape at negative gate voltages, but be insensitive to positive gate voltages. These findings confirm that the Kohn anomaly exists in a thin SWNT bundle and that the LO phonon mode changes along with the position of the Fermi level in the metallic SWNTs. In contrast, semiconducting SWNTs do not show any observable changes in the Raman spectra.
In situ Raman scattering is performed on an individual semiconducting double-walled carbon nanotu... more In situ Raman scattering is performed on an individual semiconducting double-walled carbon nanotube (DWNT) in a field-effect transistor (FET) geometry, while the transfer characteristics of the DWNT-FET are measured. Through studying the Raman spectra with response to forward and backward gate voltage (V gs) sweeping, respectively, we observe hysteresis loops in the curves of Gpeak frequency and the intensity ratio of Gto G + (I G-/I G +) as a function of V gs. These loops correlate very well with the hysteretic transfer characteristics of the device. The clear correlations suggest that Gpeak line width and I G-/I G + increase with the carrier concentration in the DWNT induced by V gs. In addition, unique Gpeak line width variations with V gs can be attributed to interband electron transitions between the energy bands of two concentric shells of the DWNT excited by G phonons.
Abnormal Raman scattering from a large-diameter ultralong single-walled carbon nanotube (SWCNT) i... more Abnormal Raman scattering from a large-diameter ultralong single-walled carbon nanotube (SWCNT) is studied in detail. Along the SWCNT, the Raman spectra show the frequencies of 1553, 1563, and 2597 cm ؊1 for G ؉ , G ؊ , and G= peaks, respectively, much lower than the corresponding frequencies well-reported both experimentally and theoretically. The significant downshifts in the peaks frequencies can be attributed to self-built tensile strain, which is likely caused by carbon nanodots decorated on the tube. After infrared laser heating is performed to one point of it, all of the Raman modes are found to shift to higher frequencies and approach their conventional values. We suggest that the SWCNTs with larger diameters easily possess such self-built strain compared to small-diameter SWCNTs because of the weaker curvature effect for the larger ones.
The current instability of carbon nanotube field effect transistors (CNTFETs) is systematically s... more The current instability of carbon nanotube field effect transistors (CNTFETs) is systematically studied under the influence of applied voltages, surfactants and temperatures. The devices were fabricated from carbon nanotubes and sodium dodecyl benzene sulfonate (SDBS) suspension using an ac dielectrophoresis (DEP) technique. The source and drain current for as-prepared p-type CNTFETs show an increase with time for the on-state, but a decrease for the off-state. Comparisons between constant and intermittent biasing conditions reveal that mobile ions could be the origin of the current instability. After removal of adsorbed SDBS, opposite transient behaviors of the current were observed, which can be attributed to the charge trapping induced screening effect.
Generally, an article is disclosed, the conductive contact elements, such as Siliziumdurchkontakt... more Generally, an article is disclosed, the conductive contact elements, such as Siliziumdurchkontaktierungen (TSVs) and methods for forming Selbiger relates. An exemplary method disclosed herein comprises forming a layer of insulating material via a contact hole formed in a semiconductor device. Here, the contact hole extending in a substrate of the semiconductor device. The method also includes performing a first planarization process to remove at least an upper portion of the layer of insulating material, which is formed outside the contact hole, and forming a conductive contact element in the contact hole, after performing the first planarization process.
Semiconductor devices and methods for forming a semiconductor device are presented. The semicondu... more Semiconductor devices and methods for forming a semiconductor device are presented. The semiconductor device includes a die which includes a die substrate having first and second major surfaces. The semiconductor device includes a passive component disposed below the second major surface of the die substrate. The passive component is electrically coupled to the die through through silicon via (TSV) contacts.
18th IEEE International Symposium on the Physical and Failure Analysis of Integrated Circuits (IPFA), 2011
In this paper, investigation of wire bonding, bumping and assembly related failures are performed... more In this paper, investigation of wire bonding, bumping and assembly related failures are performed using optical microscopy, secondary electron microscopy and transmission electron microscopy. Also, the understandings of the failures and root causes are presented. For example, corrosions caused by contaminant such as Fluorine and Cu precipitates on Al-Cu alloyed bond pads that lead to discolored or non-stick on pads
In this paper, a stoichiometric lithium niobate (SLN) crystal with the size up to 20 • 20 • 18 mm... more In this paper, a stoichiometric lithium niobate (SLN) crystal with the size up to 20 • 20 • 18 mm 3 was grown along the normal direction of the (0 1 2) facet from the 16 mol% K 2 O fluxed melt by the top-seeded solution growth method. The anisotropic thermal expansion of the SLN crystal and congruent lithium niobate (CLN) crystal was measured along different directions by using a Shimadzu thermomechanical analyzer. As compared with CLN, the SLN crystal exhibited slightly larger thermal expansion along the Z-axis and slightly smaller expansion along the X-axis. Both the SLN and CLN crystals showed strong anisotropy in the thermal expansion. The thermal expansion coefficient of SLN along the X-axis ($16.7 • 10 À6°CÀ1 at 300°C) is much larger than that along the Z-axis ($2.5 • 10 À6°CÀ1 at 300°C). Based on the experimental data and polynomial fitting results, we calculated the thermal expansion coefficients for different directions. In the case of growing the SLN crystal along the normal direction of (0 1 2) facet, we studied the radial anisotropic thermal expansion and discussed the cracking problem of the crystal according to its actual growth morphology. It is found that the cracks of SLN can be suppressed by growing the crystal along the W-axis due to its reduced radial anisotropy in the thermal expansion.
Congruent LiNbO 3 (CLN) crystals with various orientations (X-, Y-and Z-cut) and thickness (1-3.2... more Congruent LiNbO 3 (CLN) crystals with various orientations (X-, Y-and Z-cut) and thickness (1-3.2 mm) were treated by the vapor transport equilibration (VTE) method in lithium-rich environment at 1100 C. Homogeneous and crack-free crystals with nearly stoichiometric composition (>49.9 mol% Li 2 O) were obtained for different orientations. The cracking problem of X-and Y-cut samples was studied and solved by decreasing the cooling rate after the VTE treatment. The Li 2 O content in the crystal was determined by the cutoff UV absorption edge of the crystal sample. For thick samples, the diffusion of lithium atoms from side faces had influenced the composition homogeneity of the VTEtreated crystals. The CLN crystal plates with thicknesses of around 2 mm were converted into stoichiometric LiNbO 3 (SLN) by the VTE method within 200 h. Thicker CLN samples would need longer time to be converted into SLN.
ABSTRACT In this paper we grew the LiNbO3:Cu:Ce crystals with the size of φ25 mm×65 mm along the ... more ABSTRACT In this paper we grew the LiNbO3:Cu:Ce crystals with the size of φ25 mm×65 mm along the Z axis by the vertical Bridgman method. The UV-visible absorption spectra and OH− absorption spectra of 2-mm thick crystal samples cut from the bottom, middle and top parts of the as-grown crystal were measured with a Shimadzu spectrophotometer. It was found that the absorption edge at the absorption coefficient of 20 cm−1 increased along the growth axis. The oxidized samples exhibited a difference in the absorbance of OH− peaks at 3480 cm−1, while the reduced samples showed almost the same absorbance. These optical inhomogeneities were explained in terms of the nonunity segregations of Cu and Ce ions in the LiNbO3 crystal. The light-induced scattering effects of the poled crystal samples were also studied and compared using a green laser at the wavelength of 532 nm. Both oxidized and reduced X-cut samples with e-light showed stronger scattering as compared with the Z-cut samples. The reduced samples exhibited faster scattering effects than the oxidized ones. It was also found that the Z-cut sample with the light incident onto its +Z face had almost no scattering. In the case of low incident power density, the reduced samples exhibited stronger scattering than the oxidized ones at the same power density.
In situ Raman measurements have been carried out on a thin bundle of single-walled carbon nanotub... more In situ Raman measurements have been carried out on a thin bundle of single-walled carbon nanotubes (SWNTs) in field effect transistor configuration at various gate voltages. Two excitation lasers with the photon energy of 1.96 eV and 2.41 eV, respectively, are selected to excite the Raman scattering modes of metallic and semiconducting SWNTs in the bundle, respectively. For the metallic SWNTs, the G- Raman mode is found to shift to higher frequencies and narrow down its line shape at negative gate voltages, but be insensitive to positive gate voltages. These findings confirm that the Kohn anomaly exists in a thin SWNT bundle and that the LO phonon mode changes along with the position of the Fermi level in the metallic SWNTs. In contrast, semiconducting SWNTs do not show any observable changes in the Raman spectra.
The current instability of carbon nanotube field effect transistors (CNTFETs) is systematically s... more The current instability of carbon nanotube field effect transistors (CNTFETs) is systematically studied under the influence of applied voltages, surfactants and temperatures. The devices were fabricated from carbon nanotubes and sodium dodecyl benzene sulfonate (SDBS) suspension using an ac dielectrophoresis (DEP) technique. The source and drain current for as-prepared p-type CNTFETs show an increase with time for the on-state, but a decrease for the off-state. Comparisons between constant and intermittent biasing conditions reveal that mobile ions could be the origin of the current instability. After removal of adsorbed SDBS, opposite transient behaviors of the current were observed, which can be attributed to the charge trapping induced screening effect.
In situ Raman scattering is performed on an individual semiconducting double-walled carbon nanotu... more In situ Raman scattering is performed on an individual semiconducting double-walled carbon nanotube (DWNT) in a field-effect transistor (FET) geometry, while the transfer characteristics of the DWNT-FET are measured. Through studying the Raman spectra with response to forward and backward gate voltage (V gs) sweeping, respectively, we observe hysteresis loops in the curves of Gpeak frequency and the intensity ratio of Gto G + (I G-/I G +) as a function of V gs. These loops correlate very well with the hysteretic transfer characteristics of the device. The clear correlations suggest that Gpeak line width and I G-/I G + increase with the carrier concentration in the DWNT induced by V gs. In addition, unique Gpeak line width variations with V gs can be attributed to interband electron transitions between the energy bands of two concentric shells of the DWNT excited by G phonons.
In both double-walled carbon nanotube field-effect transistors (DWCNT-FETs) and single-walled car... more In both double-walled carbon nanotube field-effect transistors (DWCNT-FETs) and single-walled carbon nanotube field-effect transistors (SWCNT-FETs), ``clockwise'' hysteretic transfer characteristics are observed. These characteristics can be attributed to mobile ions or charged clusters in surfactant layers around the tube channels. Compared with SWCNT-FETs, more significant surfactant influences on the transfer characteristics are observed in DWCNT-FETs due to superior surfactant adsorption properties
Abnormal Raman scattering from a large-diameter ultralong single-walled carbon nanotube (SWCNT) i... more Abnormal Raman scattering from a large-diameter ultralong single-walled carbon nanotube (SWCNT) is studied in detail. Along the SWCNT, the Raman spectra show the frequencies of 1553, 1563, and 2597 cm ؊1 for G ؉ , G ؊ , and G= peaks, respectively, much lower than the corresponding frequencies well-reported both experimentally and theoretically. The significant downshifts in the peaks frequencies can be attributed to self-built tensile strain, which is likely caused by carbon nanodots decorated on the tube. After infrared laser heating is performed to one point of it, all of the Raman modes are found to shift to higher frequencies and approach their conventional values. We suggest that the SWCNTs with larger diameters easily possess such self-built strain compared to small-diameter SWCNTs because of the weaker curvature effect for the larger ones.
In situ Raman measurements have been carried out on a thin bundle of single-walled carbon nanotub... more In situ Raman measurements have been carried out on a thin bundle of single-walled carbon nanotubes (SWNTs) in field effect transistor configuration at various gate voltages. Two excitation lasers with the photon energy of 1.96 eV and 2.41 eV, respectively, are selected to excite the Raman scattering modes of metallic and semiconducting SWNTs in the bundle, respectively. For the metallic SWNTs, the G- Raman mode is found to shift to higher frequencies and narrow down its line shape at negative gate voltages, but be insensitive to positive gate voltages. These findings confirm that the Kohn anomaly exists in a thin SWNT bundle and that the LO phonon mode changes along with the position of the Fermi level in the metallic SWNTs. In contrast, semiconducting SWNTs do not show any observable changes in the Raman spectra.
In situ Raman scattering is performed on an individual semiconducting double-walled carbon nanotu... more In situ Raman scattering is performed on an individual semiconducting double-walled carbon nanotube (DWNT) in a field-effect transistor (FET) geometry, while the transfer characteristics of the DWNT-FET are measured. Through studying the Raman spectra with response to forward and backward gate voltage (V gs) sweeping, respectively, we observe hysteresis loops in the curves of Gpeak frequency and the intensity ratio of Gto G + (I G-/I G +) as a function of V gs. These loops correlate very well with the hysteretic transfer characteristics of the device. The clear correlations suggest that Gpeak line width and I G-/I G + increase with the carrier concentration in the DWNT induced by V gs. In addition, unique Gpeak line width variations with V gs can be attributed to interband electron transitions between the energy bands of two concentric shells of the DWNT excited by G phonons.
Abnormal Raman scattering from a large-diameter ultralong single-walled carbon nanotube (SWCNT) i... more Abnormal Raman scattering from a large-diameter ultralong single-walled carbon nanotube (SWCNT) is studied in detail. Along the SWCNT, the Raman spectra show the frequencies of 1553, 1563, and 2597 cm ؊1 for G ؉ , G ؊ , and G= peaks, respectively, much lower than the corresponding frequencies well-reported both experimentally and theoretically. The significant downshifts in the peaks frequencies can be attributed to self-built tensile strain, which is likely caused by carbon nanodots decorated on the tube. After infrared laser heating is performed to one point of it, all of the Raman modes are found to shift to higher frequencies and approach their conventional values. We suggest that the SWCNTs with larger diameters easily possess such self-built strain compared to small-diameter SWCNTs because of the weaker curvature effect for the larger ones.
The current instability of carbon nanotube field effect transistors (CNTFETs) is systematically s... more The current instability of carbon nanotube field effect transistors (CNTFETs) is systematically studied under the influence of applied voltages, surfactants and temperatures. The devices were fabricated from carbon nanotubes and sodium dodecyl benzene sulfonate (SDBS) suspension using an ac dielectrophoresis (DEP) technique. The source and drain current for as-prepared p-type CNTFETs show an increase with time for the on-state, but a decrease for the off-state. Comparisons between constant and intermittent biasing conditions reveal that mobile ions could be the origin of the current instability. After removal of adsorbed SDBS, opposite transient behaviors of the current were observed, which can be attributed to the charge trapping induced screening effect.
Generally, an article is disclosed, the conductive contact elements, such as Siliziumdurchkontakt... more Generally, an article is disclosed, the conductive contact elements, such as Siliziumdurchkontaktierungen (TSVs) and methods for forming Selbiger relates. An exemplary method disclosed herein comprises forming a layer of insulating material via a contact hole formed in a semiconductor device. Here, the contact hole extending in a substrate of the semiconductor device. The method also includes performing a first planarization process to remove at least an upper portion of the layer of insulating material, which is formed outside the contact hole, and forming a conductive contact element in the contact hole, after performing the first planarization process.
Semiconductor devices and methods for forming a semiconductor device are presented. The semicondu... more Semiconductor devices and methods for forming a semiconductor device are presented. The semiconductor device includes a die which includes a die substrate having first and second major surfaces. The semiconductor device includes a passive component disposed below the second major surface of the die substrate. The passive component is electrically coupled to the die through through silicon via (TSV) contacts.
18th IEEE International Symposium on the Physical and Failure Analysis of Integrated Circuits (IPFA), 2011
In this paper, investigation of wire bonding, bumping and assembly related failures are performed... more In this paper, investigation of wire bonding, bumping and assembly related failures are performed using optical microscopy, secondary electron microscopy and transmission electron microscopy. Also, the understandings of the failures and root causes are presented. For example, corrosions caused by contaminant such as Fluorine and Cu precipitates on Al-Cu alloyed bond pads that lead to discolored or non-stick on pads
In this paper, a stoichiometric lithium niobate (SLN) crystal with the size up to 20 • 20 • 18 mm... more In this paper, a stoichiometric lithium niobate (SLN) crystal with the size up to 20 • 20 • 18 mm 3 was grown along the normal direction of the (0 1 2) facet from the 16 mol% K 2 O fluxed melt by the top-seeded solution growth method. The anisotropic thermal expansion of the SLN crystal and congruent lithium niobate (CLN) crystal was measured along different directions by using a Shimadzu thermomechanical analyzer. As compared with CLN, the SLN crystal exhibited slightly larger thermal expansion along the Z-axis and slightly smaller expansion along the X-axis. Both the SLN and CLN crystals showed strong anisotropy in the thermal expansion. The thermal expansion coefficient of SLN along the X-axis ($16.7 • 10 À6°CÀ1 at 300°C) is much larger than that along the Z-axis ($2.5 • 10 À6°CÀ1 at 300°C). Based on the experimental data and polynomial fitting results, we calculated the thermal expansion coefficients for different directions. In the case of growing the SLN crystal along the normal direction of (0 1 2) facet, we studied the radial anisotropic thermal expansion and discussed the cracking problem of the crystal according to its actual growth morphology. It is found that the cracks of SLN can be suppressed by growing the crystal along the W-axis due to its reduced radial anisotropy in the thermal expansion.
Congruent LiNbO 3 (CLN) crystals with various orientations (X-, Y-and Z-cut) and thickness (1-3.2... more Congruent LiNbO 3 (CLN) crystals with various orientations (X-, Y-and Z-cut) and thickness (1-3.2 mm) were treated by the vapor transport equilibration (VTE) method in lithium-rich environment at 1100 C. Homogeneous and crack-free crystals with nearly stoichiometric composition (>49.9 mol% Li 2 O) were obtained for different orientations. The cracking problem of X-and Y-cut samples was studied and solved by decreasing the cooling rate after the VTE treatment. The Li 2 O content in the crystal was determined by the cutoff UV absorption edge of the crystal sample. For thick samples, the diffusion of lithium atoms from side faces had influenced the composition homogeneity of the VTEtreated crystals. The CLN crystal plates with thicknesses of around 2 mm were converted into stoichiometric LiNbO 3 (SLN) by the VTE method within 200 h. Thicker CLN samples would need longer time to be converted into SLN.
ABSTRACT In this paper we grew the LiNbO3:Cu:Ce crystals with the size of φ25 mm×65 mm along the ... more ABSTRACT In this paper we grew the LiNbO3:Cu:Ce crystals with the size of φ25 mm×65 mm along the Z axis by the vertical Bridgman method. The UV-visible absorption spectra and OH− absorption spectra of 2-mm thick crystal samples cut from the bottom, middle and top parts of the as-grown crystal were measured with a Shimadzu spectrophotometer. It was found that the absorption edge at the absorption coefficient of 20 cm−1 increased along the growth axis. The oxidized samples exhibited a difference in the absorbance of OH− peaks at 3480 cm−1, while the reduced samples showed almost the same absorbance. These optical inhomogeneities were explained in terms of the nonunity segregations of Cu and Ce ions in the LiNbO3 crystal. The light-induced scattering effects of the poled crystal samples were also studied and compared using a green laser at the wavelength of 532 nm. Both oxidized and reduced X-cut samples with e-light showed stronger scattering as compared with the Z-cut samples. The reduced samples exhibited faster scattering effects than the oxidized ones. It was also found that the Z-cut sample with the light incident onto its +Z face had almost no scattering. In the case of low incident power density, the reduced samples exhibited stronger scattering than the oxidized ones at the same power density.
In situ Raman measurements have been carried out on a thin bundle of single-walled carbon nanotub... more In situ Raman measurements have been carried out on a thin bundle of single-walled carbon nanotubes (SWNTs) in field effect transistor configuration at various gate voltages. Two excitation lasers with the photon energy of 1.96 eV and 2.41 eV, respectively, are selected to excite the Raman scattering modes of metallic and semiconducting SWNTs in the bundle, respectively. For the metallic SWNTs, the G- Raman mode is found to shift to higher frequencies and narrow down its line shape at negative gate voltages, but be insensitive to positive gate voltages. These findings confirm that the Kohn anomaly exists in a thin SWNT bundle and that the LO phonon mode changes along with the position of the Fermi level in the metallic SWNTs. In contrast, semiconducting SWNTs do not show any observable changes in the Raman spectra.
The current instability of carbon nanotube field effect transistors (CNTFETs) is systematically s... more The current instability of carbon nanotube field effect transistors (CNTFETs) is systematically studied under the influence of applied voltages, surfactants and temperatures. The devices were fabricated from carbon nanotubes and sodium dodecyl benzene sulfonate (SDBS) suspension using an ac dielectrophoresis (DEP) technique. The source and drain current for as-prepared p-type CNTFETs show an increase with time for the on-state, but a decrease for the off-state. Comparisons between constant and intermittent biasing conditions reveal that mobile ions could be the origin of the current instability. After removal of adsorbed SDBS, opposite transient behaviors of the current were observed, which can be attributed to the charge trapping induced screening effect.
In situ Raman scattering is performed on an individual semiconducting double-walled carbon nanotu... more In situ Raman scattering is performed on an individual semiconducting double-walled carbon nanotube (DWNT) in a field-effect transistor (FET) geometry, while the transfer characteristics of the DWNT-FET are measured. Through studying the Raman spectra with response to forward and backward gate voltage (V gs) sweeping, respectively, we observe hysteresis loops in the curves of Gpeak frequency and the intensity ratio of Gto G + (I G-/I G +) as a function of V gs. These loops correlate very well with the hysteretic transfer characteristics of the device. The clear correlations suggest that Gpeak line width and I G-/I G + increase with the carrier concentration in the DWNT induced by V gs. In addition, unique Gpeak line width variations with V gs can be attributed to interband electron transitions between the energy bands of two concentric shells of the DWNT excited by G phonons.
In both double-walled carbon nanotube field-effect transistors (DWCNT-FETs) and single-walled car... more In both double-walled carbon nanotube field-effect transistors (DWCNT-FETs) and single-walled carbon nanotube field-effect transistors (SWCNT-FETs), ``clockwise'' hysteretic transfer characteristics are observed. These characteristics can be attributed to mobile ions or charged clusters in surfactant layers around the tube channels. Compared with SWCNT-FETs, more significant surfactant influences on the transfer characteristics are observed in DWCNT-FETs due to superior surfactant adsorption properties
Abnormal Raman scattering from a large-diameter ultralong single-walled carbon nanotube (SWCNT) i... more Abnormal Raman scattering from a large-diameter ultralong single-walled carbon nanotube (SWCNT) is studied in detail. Along the SWCNT, the Raman spectra show the frequencies of 1553, 1563, and 2597 cm ؊1 for G ؉ , G ؊ , and G= peaks, respectively, much lower than the corresponding frequencies well-reported both experimentally and theoretically. The significant downshifts in the peaks frequencies can be attributed to self-built tensile strain, which is likely caused by carbon nanodots decorated on the tube. After infrared laser heating is performed to one point of it, all of the Raman modes are found to shift to higher frequencies and approach their conventional values. We suggest that the SWCNTs with larger diameters easily possess such self-built strain compared to small-diameter SWCNTs because of the weaker curvature effect for the larger ones.
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Papers by Shaoning Yuan