This document was prepared as an account of work sponsored by an agency of the United States Gove... more This document was prepared as an account of work sponsored by an agency of the United States Government Neither the United States Government nor the University of California nor any oftheir employees, makes any warranty, express o r implied, o r assumes any legal liability or rrsponribility for the accuracy, completeness, or usefhess of any information, apparatus,product, orprocess disdosed, o r represen tsthatits use wouldnotinfringeprivatelyowned rights. Referenceherein toany specificcommercial products, process, o r service by trade name, trademark, manufacturer, o r otherwise, doesnot necessarily constituteorimply its endorsement, recommendation,orfavoring by the United States Government or the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government o r the University of California, and shall not be used for advedisiig o r product endorsement purposes.
The spectral linewidth of a multiple-quantum-well (MQW) distributed feedback (DFB) laser is measu... more The spectral linewidth of a multiple-quantum-well (MQW) distributed feedback (DFB) laser is measured when intensity-modulated orthogonally-polarized (transverse mag- netic (TM) mode) light is injected into the laser. The spectral linewidth does not change when the modulation frequency is higher than several hundred megahertz and is almost the same as without light iqjection. However, it broadens when the in- jected orthogonally polarized light modulation frequency is close to zero. The line shape of the MQW DFB laser's lasing light becomes non-Lorentzian in shape below a modulation frequency of 500 MHz.
Conference on Lasers and Electro-Optics (CLEO 2000). Technical Digest. Postconference Edition. TOPS Vol.39 (IEEE Cat. No.00CH37088), 2000
Gas-cooled, diode-pumped, Yb:crystal lasers are envisioned to be the next-generation inertial con... more Gas-cooled, diode-pumped, Yb:crystal lasers are envisioned to be the next-generation inertial confinement fusion (ICF) solid state laser system producing high energy per pulse at modest rep-rates. Innovative solutions for building ICF lasers with high repetition rate and efficiency include: trading the flashlamps for large, low-cost laser diode arrays; using Yb:crystals for greater energy storage and thermal conductivity than Nd:glass; and
Physical review. B, Condensed matter, Jan 15, 1987
We have measured the energy-loss rates of electrons in modulation-doped ${\mathrm{Al}}_{\mathrm{x... more We have measured the energy-loss rates of electrons in modulation-doped ${\mathrm{Al}}_{\mathrm{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$As/GaAs heterojunctions at low temperatures. At the temperatures of this experiment, the energy loss is due to acoustic-phonon scattering, mostly through the deformation-potential interaction. We describe a theory of the energy-loss rate to acoustic phonons, discuss the effects of static screening, and determine a value of the deformation-potential constant by matching the theory to our experimental data. We show how the temperature dependence of the energy-loss rate can be used to determine the effectiveness of screening. In agreement with previous studies, we find that an anomalously large deformation-potential constant of 16.0 or 11.5 eV, for the screened or unscreened theory, respectively, is necessary to explain the data. However, in contrast with previous studies, we do not interpret this result as indicating some error in previous measurements of the deformation potential in bulk GaAs. Rather, we suggest that it results from some inadequacy in the model used to represent acoustic-phonon scattering in heterojunctions, or from some additional scattering mechanism not present in bulk material.
Physical review. B, Condensed matter, Jan 15, 1987
The transport of electrons in semiconductor heterolayers under the inAuence of high crossed elect... more The transport of electrons in semiconductor heterolayers under the inAuence of high crossed electric and magnetic fields has been investigated. Particular attention has been paid to realspace transfer effects. For the first time it is shown in a direct fashion that real-space transfer is associated with a transition of the two-dimensional electron gas to a three-dimensional electron distribution. This transition manifests itself by the sudden appearance of magnetoresistance (positive or negative) in perpendicular electric and magnetic fields at a critical electric field strength. Experimental results for various strengths and orientations of the magnetic field are presented and compared with a Monte Carlo transport simulation which included the Lorentz force.
Al-free active-region (ALFA) diode lasers have come of age. Record-high CW and quasi-CW powers ha... more Al-free active-region (ALFA) diode lasers have come of age. Record-high CW and quasi-CW powers have been obtained at h-0.97pm. For wavelengths at and below 0.81j.lm. ALFA-type lasers are definitely superior to Al-contiining-active lasers. Al-free lasers both open a whole new wavelength range: 0.7-0.78pm; for commercial use as well as make possible the easy fabrication of watt-range, coherent diode lasers with stable-beam behavior.
The growth of very thin, abrupt-interface, uniform epitaxial heterostructures of AlGaAs-GaAs and ... more The growth of very thin, abrupt-interface, uniform epitaxial heterostructures of AlGaAs-GaAs and GaAsP-GaAs by metalorganic chemical vapor deposition (MOCVD) is described. A brief description of the growth process as it applies to thin layers grown uniformly over large area is given. High resolution transmission electron microscopy (TEM) and secondary ion mass spectrometry (SIMS) data on lattice matched ultra-thin superlattices of
We describe a novel method for determining the energy levels of traps in a heterostructure. Our r... more We describe a novel method for determining the energy levels of traps in a heterostructure. Our results for a five period GaAsIAlGaAs (x = 0.30) superlattice show a trap in the AlGaAs at an energy level of 0.69 eV below the conduction band. This is in good agreement with a previously reported trap level 0.66 eV below the conduction band.
ABSTRACT Thin p-clad (250nm) InGaAs quantum well (QW) lasers with 200nm p+-GaAs cap layer thickne... more ABSTRACT Thin p-clad (250nm) InGaAs quantum well (QW) lasers with 200nm p+-GaAs cap layer thickness and various device configurations are studied. For wide stripe (w=50μm) lasers, abnormal lasing characteristics of very high thresholds, current on-time dependent lasing and micro-second long delays are observed. With 300nm ridge-height, micro-second long lasing delays are found in w=6μm lasers, and Q-switching in w=2.5μm and 3.5μm lasers, respectively. The unusual lasing behaviors are attributed to the decrease of transverse optical confinement caused by the increase of p+-GaAs cap layer thickness. To improve device performance and eliminate lasing delay, p+-GaAs cap layer thickness of wide stripe lasers and stripe width of narrow stripe devices have to be not greater than 170nm and 1.5μm, respectively, in thin p-clad (250nm) laser structure.
An experimental comparison is made between the losses of waveguide bends in disorder-delineated w... more An experimental comparison is made between the losses of waveguide bends in disorder-delineated waveguides in semiconductor superlattices composed of GaAs and AlAs layers for simple abrupt bends and abrupt bends with an additional half-angle guiding wall proposed by Shiina et al. [Opt. Lett. 11,736 (1986)]. For light above the band gap of bulk GaAs, the abrupt and Shiina bends were found to have to 3-dB loss angles of 3 and 7 deg, respectively. This improved performance suggests that the specific geometry of the bends is yet another degree of freedom in designing guiding structure for planar routing. Directional changes in planar waveguide structures are achieved with the use of curved regions or simple abrupt bends. Recently Shiina et al. proposed and demonstrated a modified abrupt bend, shown in Fig. 1(a), comprising two sequential half-angle bends. 1 In
An integrated manifold of quantum‐well lasers with up to three quantum wells has been fabricated ... more An integrated manifold of quantum‐well lasers with up to three quantum wells has been fabricated by metalorganic chemical vapor deposition. cw threshold current densities per well and differential quantum efficiencies are comparable to those for individual devices, and transverse far‐field patterns are single lobed. Catastrophic optical damage levels increase with increasing quantum‐well count and are substantially higher than those achieved with a single quantum‐well laser. Thermal effects in cw operation have been mitigated by using an efficient design with a high characteristic temperature in a low thermal resistance configuration.
Surface acoustic wave(SAW)properties are measured for {100}‐cut, 〈100〉‐propagating aluminumgalliu... more Surface acoustic wave(SAW)properties are measured for {100}‐cut, 〈100〉‐propagating aluminumgallium arsenide(Al x Ga1−x As) with x=0.2 and 0.4. The parameters used to characterize these properties are SAWvelocity,SAWattenuation, and piezoelectric coupling coefficient. The measuredvelocities are found to be substantially higher than those on GaAs in agreement with the theoretical predictions of Adachi. The attenuation is close to the corresponding attenuation on GaAs which is approximately 1 dB/μs. The piezoelectric coupling coefficient is measured using two independent methods and is found to be significantly higher than that of GaAs. This means that the transduction of energy from electrical to acoustical is more efficient and hence acoustic charge transport devices on Al x Ga1−x As substrates will require considerably less rf drive power. An extensive literature search has revealed no previous work, theoretical or experimental, characterizing attenuation or piezoelectric coupling of SAW on Al x Ga1−x As. The velocity has been predicted by Adachi based on a model formulated by Keyes, and has been measured by Sapriel, but the measuredvelocities reported herein correspond to the predicted values much better than the values measured by Sapriel. The measurement technique described has not, to the authors’ knowledge, been previously used for measurement of the piezoelectric coupling coefficient, and represents a convenient method of obtaining the SAW parameters experimentally.
Page 1. Structural analysis of Au-Ni-Ge and Au-Äg-Ge alloyed oìimic contacts TK Higman, M. A. Ema... more Page 1. Structural analysis of Au-Ni-Ge and Au-Äg-Ge alloyed oìimic contacts TK Higman, M. A. Emanuel, and JJ Coleman Compound Semiconductor Microelectronics ... 2. Typical (ПО) cross-section bright-field image of an ohmic Au-Ni-Ge contact alloyed at 430 °C for 24 s ...
... 6J. Simmons, J. Appi. Phys. 34, 1793 ( 1963). ¡Slew ultrafast switching mechanism in semicond... more ... 6J. Simmons, J. Appi. Phys. 34, 1793 ( 1963). ¡Slew ultrafast switching mechanism in semiconductor tieterostructures K. Hess, TK Higman, MA Emanuel, and JJ ... 14W. Frensley (private communication). IST. С LG Sollner, PE Tannenwald, DD Peck, and WD Goodhue, Appi. Phys. ...
This document was prepared as an account of work sponsored by an agency of the United States Gove... more This document was prepared as an account of work sponsored by an agency of the United States Government Neither the United States Government nor the University of California nor any oftheir employees, makes any warranty, express o r implied, o r assumes any legal liability or rrsponribility for the accuracy, completeness, or usefhess of any information, apparatus,product, orprocess disdosed, o r represen tsthatits use wouldnotinfringeprivatelyowned rights. Referenceherein toany specificcommercial products, process, o r service by trade name, trademark, manufacturer, o r otherwise, doesnot necessarily constituteorimply its endorsement, recommendation,orfavoring by the United States Government or the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government o r the University of California, and shall not be used for advedisiig o r product endorsement purposes.
The spectral linewidth of a multiple-quantum-well (MQW) distributed feedback (DFB) laser is measu... more The spectral linewidth of a multiple-quantum-well (MQW) distributed feedback (DFB) laser is measured when intensity-modulated orthogonally-polarized (transverse mag- netic (TM) mode) light is injected into the laser. The spectral linewidth does not change when the modulation frequency is higher than several hundred megahertz and is almost the same as without light iqjection. However, it broadens when the in- jected orthogonally polarized light modulation frequency is close to zero. The line shape of the MQW DFB laser's lasing light becomes non-Lorentzian in shape below a modulation frequency of 500 MHz.
Conference on Lasers and Electro-Optics (CLEO 2000). Technical Digest. Postconference Edition. TOPS Vol.39 (IEEE Cat. No.00CH37088), 2000
Gas-cooled, diode-pumped, Yb:crystal lasers are envisioned to be the next-generation inertial con... more Gas-cooled, diode-pumped, Yb:crystal lasers are envisioned to be the next-generation inertial confinement fusion (ICF) solid state laser system producing high energy per pulse at modest rep-rates. Innovative solutions for building ICF lasers with high repetition rate and efficiency include: trading the flashlamps for large, low-cost laser diode arrays; using Yb:crystals for greater energy storage and thermal conductivity than Nd:glass; and
Physical review. B, Condensed matter, Jan 15, 1987
We have measured the energy-loss rates of electrons in modulation-doped ${\mathrm{Al}}_{\mathrm{x... more We have measured the energy-loss rates of electrons in modulation-doped ${\mathrm{Al}}_{\mathrm{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$As/GaAs heterojunctions at low temperatures. At the temperatures of this experiment, the energy loss is due to acoustic-phonon scattering, mostly through the deformation-potential interaction. We describe a theory of the energy-loss rate to acoustic phonons, discuss the effects of static screening, and determine a value of the deformation-potential constant by matching the theory to our experimental data. We show how the temperature dependence of the energy-loss rate can be used to determine the effectiveness of screening. In agreement with previous studies, we find that an anomalously large deformation-potential constant of 16.0 or 11.5 eV, for the screened or unscreened theory, respectively, is necessary to explain the data. However, in contrast with previous studies, we do not interpret this result as indicating some error in previous measurements of the deformation potential in bulk GaAs. Rather, we suggest that it results from some inadequacy in the model used to represent acoustic-phonon scattering in heterojunctions, or from some additional scattering mechanism not present in bulk material.
Physical review. B, Condensed matter, Jan 15, 1987
The transport of electrons in semiconductor heterolayers under the inAuence of high crossed elect... more The transport of electrons in semiconductor heterolayers under the inAuence of high crossed electric and magnetic fields has been investigated. Particular attention has been paid to realspace transfer effects. For the first time it is shown in a direct fashion that real-space transfer is associated with a transition of the two-dimensional electron gas to a three-dimensional electron distribution. This transition manifests itself by the sudden appearance of magnetoresistance (positive or negative) in perpendicular electric and magnetic fields at a critical electric field strength. Experimental results for various strengths and orientations of the magnetic field are presented and compared with a Monte Carlo transport simulation which included the Lorentz force.
Al-free active-region (ALFA) diode lasers have come of age. Record-high CW and quasi-CW powers ha... more Al-free active-region (ALFA) diode lasers have come of age. Record-high CW and quasi-CW powers have been obtained at h-0.97pm. For wavelengths at and below 0.81j.lm. ALFA-type lasers are definitely superior to Al-contiining-active lasers. Al-free lasers both open a whole new wavelength range: 0.7-0.78pm; for commercial use as well as make possible the easy fabrication of watt-range, coherent diode lasers with stable-beam behavior.
The growth of very thin, abrupt-interface, uniform epitaxial heterostructures of AlGaAs-GaAs and ... more The growth of very thin, abrupt-interface, uniform epitaxial heterostructures of AlGaAs-GaAs and GaAsP-GaAs by metalorganic chemical vapor deposition (MOCVD) is described. A brief description of the growth process as it applies to thin layers grown uniformly over large area is given. High resolution transmission electron microscopy (TEM) and secondary ion mass spectrometry (SIMS) data on lattice matched ultra-thin superlattices of
We describe a novel method for determining the energy levels of traps in a heterostructure. Our r... more We describe a novel method for determining the energy levels of traps in a heterostructure. Our results for a five period GaAsIAlGaAs (x = 0.30) superlattice show a trap in the AlGaAs at an energy level of 0.69 eV below the conduction band. This is in good agreement with a previously reported trap level 0.66 eV below the conduction band.
ABSTRACT Thin p-clad (250nm) InGaAs quantum well (QW) lasers with 200nm p+-GaAs cap layer thickne... more ABSTRACT Thin p-clad (250nm) InGaAs quantum well (QW) lasers with 200nm p+-GaAs cap layer thickness and various device configurations are studied. For wide stripe (w=50μm) lasers, abnormal lasing characteristics of very high thresholds, current on-time dependent lasing and micro-second long delays are observed. With 300nm ridge-height, micro-second long lasing delays are found in w=6μm lasers, and Q-switching in w=2.5μm and 3.5μm lasers, respectively. The unusual lasing behaviors are attributed to the decrease of transverse optical confinement caused by the increase of p+-GaAs cap layer thickness. To improve device performance and eliminate lasing delay, p+-GaAs cap layer thickness of wide stripe lasers and stripe width of narrow stripe devices have to be not greater than 170nm and 1.5μm, respectively, in thin p-clad (250nm) laser structure.
An experimental comparison is made between the losses of waveguide bends in disorder-delineated w... more An experimental comparison is made between the losses of waveguide bends in disorder-delineated waveguides in semiconductor superlattices composed of GaAs and AlAs layers for simple abrupt bends and abrupt bends with an additional half-angle guiding wall proposed by Shiina et al. [Opt. Lett. 11,736 (1986)]. For light above the band gap of bulk GaAs, the abrupt and Shiina bends were found to have to 3-dB loss angles of 3 and 7 deg, respectively. This improved performance suggests that the specific geometry of the bends is yet another degree of freedom in designing guiding structure for planar routing. Directional changes in planar waveguide structures are achieved with the use of curved regions or simple abrupt bends. Recently Shiina et al. proposed and demonstrated a modified abrupt bend, shown in Fig. 1(a), comprising two sequential half-angle bends. 1 In
An integrated manifold of quantum‐well lasers with up to three quantum wells has been fabricated ... more An integrated manifold of quantum‐well lasers with up to three quantum wells has been fabricated by metalorganic chemical vapor deposition. cw threshold current densities per well and differential quantum efficiencies are comparable to those for individual devices, and transverse far‐field patterns are single lobed. Catastrophic optical damage levels increase with increasing quantum‐well count and are substantially higher than those achieved with a single quantum‐well laser. Thermal effects in cw operation have been mitigated by using an efficient design with a high characteristic temperature in a low thermal resistance configuration.
Surface acoustic wave(SAW)properties are measured for {100}‐cut, 〈100〉‐propagating aluminumgalliu... more Surface acoustic wave(SAW)properties are measured for {100}‐cut, 〈100〉‐propagating aluminumgallium arsenide(Al x Ga1−x As) with x=0.2 and 0.4. The parameters used to characterize these properties are SAWvelocity,SAWattenuation, and piezoelectric coupling coefficient. The measuredvelocities are found to be substantially higher than those on GaAs in agreement with the theoretical predictions of Adachi. The attenuation is close to the corresponding attenuation on GaAs which is approximately 1 dB/μs. The piezoelectric coupling coefficient is measured using two independent methods and is found to be significantly higher than that of GaAs. This means that the transduction of energy from electrical to acoustical is more efficient and hence acoustic charge transport devices on Al x Ga1−x As substrates will require considerably less rf drive power. An extensive literature search has revealed no previous work, theoretical or experimental, characterizing attenuation or piezoelectric coupling of SAW on Al x Ga1−x As. The velocity has been predicted by Adachi based on a model formulated by Keyes, and has been measured by Sapriel, but the measuredvelocities reported herein correspond to the predicted values much better than the values measured by Sapriel. The measurement technique described has not, to the authors’ knowledge, been previously used for measurement of the piezoelectric coupling coefficient, and represents a convenient method of obtaining the SAW parameters experimentally.
Page 1. Structural analysis of Au-Ni-Ge and Au-Äg-Ge alloyed oìimic contacts TK Higman, M. A. Ema... more Page 1. Structural analysis of Au-Ni-Ge and Au-Äg-Ge alloyed oìimic contacts TK Higman, M. A. Emanuel, and JJ Coleman Compound Semiconductor Microelectronics ... 2. Typical (ПО) cross-section bright-field image of an ohmic Au-Ni-Ge contact alloyed at 430 °C for 24 s ...
... 6J. Simmons, J. Appi. Phys. 34, 1793 ( 1963). ¡Slew ultrafast switching mechanism in semicond... more ... 6J. Simmons, J. Appi. Phys. 34, 1793 ( 1963). ¡Slew ultrafast switching mechanism in semiconductor tieterostructures K. Hess, TK Higman, MA Emanuel, and JJ ... 14W. Frensley (private communication). IST. С LG Sollner, PE Tannenwald, DD Peck, and WD Goodhue, Appi. Phys. ...
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