We report the use of direct write UV laser ablation to create microstructures in polymer film sub... more We report the use of direct write UV laser ablation to create microstructures in polymer film substrates. An integrated chip-MS device is fabricated combining a microfluidic channel with an electrospray tip. Mass spectral data is presented demonstrating protein sample compatibility and excellent spray stability.
Although the group IIB metal dimers (Zn2, Cd2, Hg2) have received considerable attention as poten... more Although the group IIB metal dimers (Zn2, Cd2, Hg2) have received considerable attention as potential bound → free (excimer) lasers, little is known of the electron ic excited states above the lowest-lying level (3Π g ). This paper describes experiments in which the absorption spectrum of Zn2(4p3Π g ) in the visible and ultraviolet has been observed. A quartz cell containing several milligrams of zinc was evacuated to < 10-7 Torr, sealed and heated to ~800°C. Excited Zn atoms were produced by pumping the atomic 4p3P1 ← 4s21S0 transition at 307.6 nm with an untuned XeCI laser. Diatomic molecules are subsequently formed in three-body collisions of a 4p3P1 atom with two background 1S0 species. A pulsed Xe lamp (~300-nm FWHM) provided the probe continuum. Collimated and spatially filtered, the beam from the lamp propagated through the XeCI laser-produced excited region and was detected by a 0.25-m spectrograph/diode array combination. The UV and visible are dominated by absorption bands centered at 290,390, and 420 nm. Weaker but significant bands in the 450-460-nm region are also observed. Spectroscopic identification of these bands is discussed.
Fabrication of group-III nitride electronic and photonic devices relies heavily on f & ai3 # patt... more Fabrication of group-III nitride electronic and photonic devices relies heavily on f & ai3 # pattern features with anisotropic profiles, smooth surface morphologies, etch rates often exceedmg 1 pdmin, and a low degree of plasma-induced damage. Patterning these materials has been especially difficult due to their high bond energies and their relatively inert chemical nature as compared to other compound semiconductors. :However, high-density plasma etching has been an effective patterning technique due to ion fluxes which are 2 to 4 orders of magnitude higher than conventional RIE systems. GaN etch rates as high as-1.3 pm/min.have been reported in ECR generated IC1 plasmas at-150 V dc-bias. In this study, we report high-density GaN etch results for ECR-and ICP-generated plasmas as a function of C4-and BC1,-based plasma chemistries. ' DISCLAIMER This report was prepared as an account of work sponsored by an agency of the
Although the lowest lying ion pair states of the Column IIB metal-halide molecules have been well... more Although the lowest lying ion pair states of the Column IIB metal-halide molecules have been well studied in emission, little is known of the more highly excited electronic states. This paper describes the observation of visible and UV absorption bands in cadmium monoiodide (Cdl) and mercury bromide (HgBr) in which the initial state is the laser’s upper level (B2Σ). In each case, the band terminates on a covalent state that correlates with an excited metal atom (in the lowest-lying 3P manifold) and a ground-state halogen atom. Such bands are certain to exist for the rare gas halide (RGH) molecules as well as it was recognized1 soon after discovery of the RGH lasers that these absorptions (although not previously observed) could represent a serious loss channel.
Currently, commercial LEDs based on AlGaInN emit light efficiently from the ultraviolet-blue to t... more Currently, commercial LEDs based on AlGaInN emit light efficiently from the ultraviolet-blue to the green portion of the visible wavelength spectrum. Data are presented on AlGaInN LEDs grown by organometallic vapor phase epitaxy (OMVPE). Designs for high-power AlGaInN LEDs are presented along with their performance in terms of output power and efficiency. Finally, present and potential applications for high-power AlGaInN
We report the reproducible molecular beam epitaxial growth of Be-doped piecewise linearly graded ... more We report the reproducible molecular beam epitaxial growth of Be-doped piecewise linearly graded (Al,Ga)As distributed Bragg reflectors that have vertical series resistivities near bulk values. For mirrors with three linear segments per interface, the center wavelength reproducibility is 0.1% and the series resistivity is as low as 1.8×10-5 Ω cm2 for hole concentrations of 5×1018 cm-3. Measured reflectivities of 6.0% per interface are comparable to conventional single-linear-grade mirrors. Vertical-cavity surface-emitting lasers incorporating these mirrors exhibit record-low voltage thresholds of less than 1.5 V.
A method is described for reproducibly controlling layer thickness and varying layer composition ... more A method is described for reproducibly controlling layer thickness and varying layer composition in an MBE deposition process. In particular, the present invention includes epitaxially depositing a plurality of layers of material on a substrate with a plurality of growth cycles whereby the average of the instantaneous growth rates for each growth cycle and from one growth cycle to the next remains substantially constant as a function of time.
We report the reproducible molecular beam epitaxial growth of Be-doped piecewise linearly graded ... more We report the reproducible molecular beam epitaxial growth of Be-doped piecewise linearly graded (Al,Ga)As distributed Bragg reflectors that have vertical series resistivities near bulk values. For mirrors with three linear segments per interface, the center wavelength reproducibility is 0.1% and the series resistivity is as low as 1.8×10−5 Ω cm2 for hole concentrations of 5×1018 cm−3. Measured reflectivities of 6.0% per interface are comparable to conventional single-linear-grade mirrors. Vertical-cavity surface-emitting lasers incorporating these mirrors exhibit record-low voltage thresholds of less than 1.5 V.
Page 1. Method for accurate growth of vertical-cavity surface-emitting lasers SA Chalmers and KP ... more Page 1. Method for accurate growth of vertical-cavity surface-emitting lasers SA Chalmers and KP Killeen Sandia National Laboratories, Albuquerque, New Mexico 87185 (Received 14 September 1992; accepted for publication 16 December 1992) ...
A micro-device 10 comprises a planar substrate 12 with a microchannel 18 a cover plate 30, sample... more A micro-device 10 comprises a planar substrate 12 with a microchannel 18 a cover plate 30, sample inlet port 20 and a protruding electro-spray emitter 42 suitably shaped to permit the formation of a Taylor cone from a sample passing there-through, under the influence of an electric field. Fig. 1C showing the device post removal of portions of material to form the protrusion of the electro-spray emitter 42. Also disclosed is a method of manufacture of the aforementioned micro-device comprising the use of "non-mechanical" material removal means, negating the need for "photo-resist masking", such as laser ablation or photochemical etching. Further disclosed is the use of the aforementioned micro-device in electro-spray emission, involving the passing a sample through the device and forming a Taylor cone of a sample material under the influence of an electric field at the mouth 22 of the emitter 42. The micro-device 10 may be used in the preparation of samples for su...
The Agilent Chip Cube Interface is a microfluidic chip-based technology originally designed for n... more The Agilent Chip Cube Interface is a microfluidic chip-based technology originally designed for nanospray molecular mass spectrometry in which the sample enrichment, nano-column, tubing, connectors and spray tip were integrated into a single biocompatible chip. Here we describe the hyphenation of the Chip Cube Interface to ICP-MS via modification of the standard HPLC chip design and a new total consumption nebuliser suitable for flow rates as low as 300nLmin(-1). The potential of the instrument to eliminate common nanoLC - ICP-MS shortcomings such as leaks, blockages and band-broadening was demonstrated via analysis of cyanocobalamin in equine plasma. The method was linear over three orders of magnitude with an r(2) of 0.9999, the peak area repeatability was 1.9% (n=7), and the detection limit was 14ngmL(-1). This novel configuration of the Chip Cube Interface coupled to ICP-MS is a suitable platform for the analysis of biomolecules associated with trace metals and speciation applic...
We report the use of direct write UV laser ablation to create microstructures in polymer film sub... more We report the use of direct write UV laser ablation to create microstructures in polymer film substrates. An integrated chip-MS device is fabricated combining a microfluidic channel with an electrospray tip. Mass spectral data is presented demonstrating protein sample compatibility and excellent spray stability.
Although the group IIB metal dimers (Zn2, Cd2, Hg2) have received considerable attention as poten... more Although the group IIB metal dimers (Zn2, Cd2, Hg2) have received considerable attention as potential bound → free (excimer) lasers, little is known of the electron ic excited states above the lowest-lying level (3Π g ). This paper describes experiments in which the absorption spectrum of Zn2(4p3Π g ) in the visible and ultraviolet has been observed. A quartz cell containing several milligrams of zinc was evacuated to < 10-7 Torr, sealed and heated to ~800°C. Excited Zn atoms were produced by pumping the atomic 4p3P1 ← 4s21S0 transition at 307.6 nm with an untuned XeCI laser. Diatomic molecules are subsequently formed in three-body collisions of a 4p3P1 atom with two background 1S0 species. A pulsed Xe lamp (~300-nm FWHM) provided the probe continuum. Collimated and spatially filtered, the beam from the lamp propagated through the XeCI laser-produced excited region and was detected by a 0.25-m spectrograph/diode array combination. The UV and visible are dominated by absorption bands centered at 290,390, and 420 nm. Weaker but significant bands in the 450-460-nm region are also observed. Spectroscopic identification of these bands is discussed.
Fabrication of group-III nitride electronic and photonic devices relies heavily on f & ai3 # patt... more Fabrication of group-III nitride electronic and photonic devices relies heavily on f & ai3 # pattern features with anisotropic profiles, smooth surface morphologies, etch rates often exceedmg 1 pdmin, and a low degree of plasma-induced damage. Patterning these materials has been especially difficult due to their high bond energies and their relatively inert chemical nature as compared to other compound semiconductors. :However, high-density plasma etching has been an effective patterning technique due to ion fluxes which are 2 to 4 orders of magnitude higher than conventional RIE systems. GaN etch rates as high as-1.3 pm/min.have been reported in ECR generated IC1 plasmas at-150 V dc-bias. In this study, we report high-density GaN etch results for ECR-and ICP-generated plasmas as a function of C4-and BC1,-based plasma chemistries. ' DISCLAIMER This report was prepared as an account of work sponsored by an agency of the
Although the lowest lying ion pair states of the Column IIB metal-halide molecules have been well... more Although the lowest lying ion pair states of the Column IIB metal-halide molecules have been well studied in emission, little is known of the more highly excited electronic states. This paper describes the observation of visible and UV absorption bands in cadmium monoiodide (Cdl) and mercury bromide (HgBr) in which the initial state is the laser’s upper level (B2Σ). In each case, the band terminates on a covalent state that correlates with an excited metal atom (in the lowest-lying 3P manifold) and a ground-state halogen atom. Such bands are certain to exist for the rare gas halide (RGH) molecules as well as it was recognized1 soon after discovery of the RGH lasers that these absorptions (although not previously observed) could represent a serious loss channel.
Currently, commercial LEDs based on AlGaInN emit light efficiently from the ultraviolet-blue to t... more Currently, commercial LEDs based on AlGaInN emit light efficiently from the ultraviolet-blue to the green portion of the visible wavelength spectrum. Data are presented on AlGaInN LEDs grown by organometallic vapor phase epitaxy (OMVPE). Designs for high-power AlGaInN LEDs are presented along with their performance in terms of output power and efficiency. Finally, present and potential applications for high-power AlGaInN
We report the reproducible molecular beam epitaxial growth of Be-doped piecewise linearly graded ... more We report the reproducible molecular beam epitaxial growth of Be-doped piecewise linearly graded (Al,Ga)As distributed Bragg reflectors that have vertical series resistivities near bulk values. For mirrors with three linear segments per interface, the center wavelength reproducibility is 0.1% and the series resistivity is as low as 1.8×10-5 Ω cm2 for hole concentrations of 5×1018 cm-3. Measured reflectivities of 6.0% per interface are comparable to conventional single-linear-grade mirrors. Vertical-cavity surface-emitting lasers incorporating these mirrors exhibit record-low voltage thresholds of less than 1.5 V.
A method is described for reproducibly controlling layer thickness and varying layer composition ... more A method is described for reproducibly controlling layer thickness and varying layer composition in an MBE deposition process. In particular, the present invention includes epitaxially depositing a plurality of layers of material on a substrate with a plurality of growth cycles whereby the average of the instantaneous growth rates for each growth cycle and from one growth cycle to the next remains substantially constant as a function of time.
We report the reproducible molecular beam epitaxial growth of Be-doped piecewise linearly graded ... more We report the reproducible molecular beam epitaxial growth of Be-doped piecewise linearly graded (Al,Ga)As distributed Bragg reflectors that have vertical series resistivities near bulk values. For mirrors with three linear segments per interface, the center wavelength reproducibility is 0.1% and the series resistivity is as low as 1.8×10−5 Ω cm2 for hole concentrations of 5×1018 cm−3. Measured reflectivities of 6.0% per interface are comparable to conventional single-linear-grade mirrors. Vertical-cavity surface-emitting lasers incorporating these mirrors exhibit record-low voltage thresholds of less than 1.5 V.
Page 1. Method for accurate growth of vertical-cavity surface-emitting lasers SA Chalmers and KP ... more Page 1. Method for accurate growth of vertical-cavity surface-emitting lasers SA Chalmers and KP Killeen Sandia National Laboratories, Albuquerque, New Mexico 87185 (Received 14 September 1992; accepted for publication 16 December 1992) ...
A micro-device 10 comprises a planar substrate 12 with a microchannel 18 a cover plate 30, sample... more A micro-device 10 comprises a planar substrate 12 with a microchannel 18 a cover plate 30, sample inlet port 20 and a protruding electro-spray emitter 42 suitably shaped to permit the formation of a Taylor cone from a sample passing there-through, under the influence of an electric field. Fig. 1C showing the device post removal of portions of material to form the protrusion of the electro-spray emitter 42. Also disclosed is a method of manufacture of the aforementioned micro-device comprising the use of "non-mechanical" material removal means, negating the need for "photo-resist masking", such as laser ablation or photochemical etching. Further disclosed is the use of the aforementioned micro-device in electro-spray emission, involving the passing a sample through the device and forming a Taylor cone of a sample material under the influence of an electric field at the mouth 22 of the emitter 42. The micro-device 10 may be used in the preparation of samples for su...
The Agilent Chip Cube Interface is a microfluidic chip-based technology originally designed for n... more The Agilent Chip Cube Interface is a microfluidic chip-based technology originally designed for nanospray molecular mass spectrometry in which the sample enrichment, nano-column, tubing, connectors and spray tip were integrated into a single biocompatible chip. Here we describe the hyphenation of the Chip Cube Interface to ICP-MS via modification of the standard HPLC chip design and a new total consumption nebuliser suitable for flow rates as low as 300nLmin(-1). The potential of the instrument to eliminate common nanoLC - ICP-MS shortcomings such as leaks, blockages and band-broadening was demonstrated via analysis of cyanocobalamin in equine plasma. The method was linear over three orders of magnitude with an r(2) of 0.9999, the peak area repeatability was 1.9% (n=7), and the detection limit was 14ngmL(-1). This novel configuration of the Chip Cube Interface coupled to ICP-MS is a suitable platform for the analysis of biomolecules associated with trace metals and speciation applic...
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Papers by Kevin Killeen