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25 Sep 1995

Volume 67, Issue 13, pp. 1797-1946

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Chirp of passively and actively mode‐locked semiconductor lasers

M. Schell, J. Yu, M. Tsuchiya, and T. Kamiya

Appl. Phys. Lett. 67, 1797 (1995); http://dx.doi.org/10.1063/1.115062 (3 pages) | Cited 12 times

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The experimental observation of blue‐chirped pulses for passive mode‐locking and red‐chirped pulses for active mode‐locking is theoretically explained as a consequence of different α parameters in the gain and absorber section. The influence of nonlinear gain due to carrier heating is also discussed. The knowledge of the chirp is crucial for the optimization of passively mode‐locked lasers for spectrally narrow emission or for the emission of linearly chirped pulses. © 1995 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Fc Modulation, tuning, and mode locking

Grating coupled multicolor quantum well infrared photodetectors

M. Z. Tidrow, K. K. Choi, A. J. DeAnni, W. H. Chang, and S. P. Svensson

Appl. Phys. Lett. 67, 1800 (1995); http://dx.doi.org/10.1063/1.115063 (3 pages) | Cited 19 times

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Gratings of different period spacings are fabricated on quantum well infrared photodetectors having two‐stack multiple quantum wells (MQW) to determine the grating coupling efficiency in multicolor detection. The peak wavelength of each MQW is 4.8 and 9.4 μm, respectively, covering the two atmospheric windows. 2D gratings of box‐shaped cavities with grating period either in 3 or 4.6 μm spacing are used to coupled normal incident light into the detector. Comparing detectors with and without gratings at either normal or 45° facet incidence, the detectors with an optimized grating show efficient light coupling for both wavelengths due to the fact that the longer wavelength in the present case is an integral multiple of the shorter wavelength. The optimized long wavelength grating couples the shorter wavelength through additional higher orders of diffraction. © 1995 American Institute of Physics.
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85.60.Gz Photodetectors (including infrared and CCD detectors)

Pulsed laser deposition of BaTiO3 thin films and their optical properties

D. H. Kim and H. S. Kwok

Appl. Phys. Lett. 67, 1803 (1995); http://dx.doi.org/10.1063/1.115064 (3 pages) | Cited 37 times

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Highly oriented a‐axis BaTiO3 thin films were grown by pulsed laser deposition on (001) MgO substrates. The full width at half‐maximum of the (200) BaTiO3 rocking curve was as narrow as 0.6°. A large hysteretic quadratic electro‐optic effect was observed in a transverse geometry at 6328 Å. A birefringence shift up to 3×10−3 was measured at an applied dc electric field of 1 kV/mm. It was found that laser repetition rate plays an important role on the surface morphology of the deposited films. © 1995 American Institute of Physics.
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42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
78.20.Jq Electro-optical effects
81.15.Fg Pulsed laser ablation deposition

Optical heterodyne detection of 60 GHz electro‐optic modulation from polymer waveguide modulators

Wenshen Wang, Datong Chen, Harold R. Fetterman, Yongqiang Shi, William H. Steier, Larry R. Dalton, and Pei‐Ming D. Chow

Appl. Phys. Lett. 67, 1806 (1995); http://dx.doi.org/10.1063/1.115065 (3 pages) | Cited 30 times

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An optical heterodyne technique has been used to demonstrate electro‐optic modulation up to 60 GHz, the highest reported to date, in polymer waveguide modulators. The frequency response of the device from 40 to 60 GHz was obtained by measuring the frequency down converted modulation signal with a low frequency photodetector. No rolling‐off was identifiable from the measured device response, indicating no fundamental material limitations in this frequency range for the polymer material which we used. Such an optical heterdyne system can be a powerful tool for modulator characterization at millimeter wave frequencies because of its high sensitivity and low frequency demands on photoreceivers. © 1995 American Institute of Physics.
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42.79.Hp Optical processors, correlators, and modulators

Picosecond spectroscopy of optically modulated high‐speed laser diodes

D. H. Sutter, H. Schneider, S. Weisser, J. D. Ralston, and E. C. Larkins

Appl. Phys. Lett. 67, 1809 (1995); http://dx.doi.org/10.1063/1.115066 (3 pages) | Cited 4 times

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The emission transients of optically excited high‐speed multiple quantum well laser diodes have been measured by up‐converting the emission in a nonlinear crystal. From the gain‐switched oscillation the intrinsic resonance frequency and damping factor are determined. The high temporal resolution allows us to observe additional short period oscillations with a frequency of about 170 GHz. Numerical solution of the traveling wave rate equations indicates that these high frequency oscillations arise due to inhomogeneous carrier injection. © 1995 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.-v Laser optical systems: design and operation

Double layers of single domains formed by rapid thermal annealing of proton‐exchanged LiTaO3

Cangsang Zhao and Reinhart Engelmann

Appl. Phys. Lett. 67, 1812 (1995); http://dx.doi.org/10.1063/1.115067 (3 pages) | Cited 1 time

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A double layer of single domains with opposing polarizations has been formed on both c faces by rapid thermal annealing of proton‐exchanged z‐cut LiTaO3 at above the Curie temperature. The formed top single‐domain layers have inward‐directed polarization and the single‐domain layers underneath have outward‐directed polarization. The domain structure development for an annealing range from 2 s to 10 min has been investigated. The results are discussed in relation to recently proposed models for the domain‐inversion mechanisms in LiTaO3 and LiNbO3. © 1995 American Institute of Physics.
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77.80.Dj Domain structure; hysteresis
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates

Laser diode pumped 106 mW blue upconversion fiber laser

S. Sanders, R. G. Waarts, D. G. Mehuys, and D. F. Welch

Appl. Phys. Lett. 67, 1815 (1995); http://dx.doi.org/10.1063/1.115412 (3 pages) | Cited 40 times

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A laser diode pumped Tm3+‐doped ZBLAN fiber upconversion laser is demonstrated with blue output power levels up to 106 mW. Differential optical‐to‐optical conversion efficiencies up to 30% are measured with respect to pump power coupled into the upconversion fiber. A single spatial mode blue output beam is demonstrated, with an M2 value of 1.4. © 1995 American Institute of Physics.  
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42.55.Rz Doped-insulator lasers and other solid state lasers
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation

New nonlinear optical crystal: Cesium lithium borate

Yusuke Mori, Ikuo Kuroda, Satoshi Nakajima, Takatomo Sasaki, and Sadao Nakai

Appl. Phys. Lett. 67, 1818 (1995); http://dx.doi.org/10.1063/1.115413 (3 pages) | Cited 132 times

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A new nonlinear optical crystal CsLiB6O10 (CLBO), is described that can be grown from either stoichiometric melt or from solution. A large, high quality single crystal with dimensions of 14×11×11 cm3 was obtained by the top‐seeded Kyropoulos method. Fourth harmonic and fifth harmonic generations of the 1.064 μm Nd:YAG laser radiation with type‐I phase matching were realized in the CLBO crystal. Output pulse energies obtained were 110 mJ at 266 nm and 35 mJ at 213 nm. © 1995 American Institute of Physics.
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42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
81.10.-h Methods of crystal growth; physics and chemistry of crystal growth, crystal morphology, and orientation

Wavelength insensitive passive polarization converter fabricated by poled polymer waveguides

Min‐Cheol Oh, Sang‐Yung Shin, Wol‐Yon Hwang, and Jang‐Joo Kim

Appl. Phys. Lett. 67, 1821 (1995); http://dx.doi.org/10.1063/1.115414 (3 pages) | Cited 15 times

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A passive TE to TM polarization mode converter is fabricated by using poled polymer waveguides. The optic axis of the poling induced waveguide is slowly rotated 90° by using a slowly varying structure of poling electrodes. Thus the polarization conversion is achieved as the guided mode propagates through the waveguide. TE to TM mode conversion is observed with a polarization extinction ratio higher than 30 dB, and the excess loss is less than 1 dB. The polarization conversion is relatively insensitive to wavelength since the device contains no periodic structures. These devices are easier to fabricate than others containing periodic structures. © 1995 American Institute of Physics.
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42.79.Ci Filters, zone plates, and polarizers
42.79.Gn Optical waveguides and couplers

Physical modeling of pyrometric interferometry during molecular beam epitaxial growth of III–V layered structures

H. P. Lee, E. Ranalli, and X. Liu

Appl. Phys. Lett. 67, 1824 (1995); http://dx.doi.org/10.1063/1.115415 (3 pages) | Cited 3 times

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A detailed physical model of pyrometric interferometry during molecular beam epitaxy growth of III–V layers is presented. The pyrometric radiation intensity is expressed as spatial convolution of the spontaneous emission rates and the propagation response of the sample. The new formalism, together with empirical modeling of background signal provide a generic framework for implementing a model‐reference closed‐loop control system for epitaxial growth of multilayer structures. © 1995 American Institute of Physics.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
78.60.-b Other luminescence and radiative recombination

Generalized formula for the surface stiffness of fluid‐saturated porous media containing parallel pore channels

Peter B. Nagy and Adnan H. Nayfeh

Appl. Phys. Lett. 67, 1827 (1995); http://dx.doi.org/10.1063/1.115416 (3 pages) | Cited 7 times

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The surface stiffness of a fluid‐saturated porous solid is defined as the ratio between a small change in capillary pressure and the average displacement of the boundary due to the resulting rise or fall of the fluid level in the pore channels. When the surface pores are structurally open, the surface stiffness is entirely due to the stiffness of the microscopic fluid membranes extended by capillary forces over the surface pores. Due to interfacial tension between the immiscible wetting fluid in the pores and nonwetting fluid (air) above the surface, essentially closed‐pore boundary conditions can prevail at the interface. It has recently been shown that the surface stiffness of a porous material containing cylindrical pores can be calculated simply as the surface tension of the saturating fluid divided by the static permeability of the porous solid [P. B. Nagy, Appl. Phys. Lett. 60, 2735 (1992)]. In this letter, we show that the same simple relationship can be generalized for the surface stiffness of fluid‐saturated porous media containing parallel prismatic pore channels of any number, size, or shape. © 1995 American Institute of Physics.
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68.43.-h Chemisorption/physisorption: adsorbates on surfaces

Characterization of structural defects in wurtzite GaN grown on 6H SiC using plasma‐enhanced molecular beam epitaxy

David J. Smith, D. Chandrasekhar, B. Sverdlov, A. Botchkarev, A. Salvador, and H. Morkoç

Appl. Phys. Lett. 67, 1830 (1995); http://dx.doi.org/10.1063/1.115417 (3 pages) | Cited 48 times

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Thin wurtzite GaN films have been grown by plasma‐enhanced molecular beam epitaxy on the basal plane of 6H SiC, with and without AlN buffer layers. Threading defects, identified from high‐resolution electron micrographs as double‐positioning boundaries (DPBs), originate at the substrate–buffer and/or buffer–film interfaces. The density of these faults seems to be related to the smoothness of the substrate, so that their occurrence emphasizes the importance of adequate substrate preparation. Stacking faults within the GaN are often visible parallel to the SiC substrate basal plane, sometimes terminating at the DPBs. These faults are related to the particular growth conditions, with greatly decreased density obtained for lower plasma power during GaN deposition. Growth of high quality GaN without stacking faults was achieved without using AlN buffer layers by deposition directly onto a vicinal SiC surface having a miscut angle of 4°. Such stepped substrates represent a potentially useful means for controlled growth of the DPBs, which could then serve as suitable stress‐relieving defects in lieu of misfit dislocations. © 1995 American Institute of Physics.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Stress evolution during the growth of ultrathin layers of iron and iron silicide on Si(111)

D. Sander, A. Enders, and J. Kirschner

Appl. Phys. Lett. 67, 1833 (1995); http://dx.doi.org/10.1063/1.115418 (3 pages) | Cited 9 times

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Using a simple optical deflection technique, we measured continuously the mechanical stress during the growth of Fe films of 0.1–1.5 nm thickness on Si(111) in ultrahigh vacuum (UHV). The stress versus coverage dependence is discussed in view of the different growth modes during the various stages of Fe deposition. The deposition of up to 0.3 nm Fe induces a compressive stress of −1 N/m. We assign this stress to the formation of a reactive Fe–Si interface layer with a silicidelike structure. Subsequent Fe deposition at 300 K leads to a small tensile stress of 0.7 N/m, whereas the deposition at 600 K induces a high tensile film stress of 18 N/m. At 600 K substrate temperature, a solid‐state reaction between Fe and Si sets in, and the silicide β‐FeSi2 is formed. The decrease of the atomic volume of Si by 7% in this silicide is proposed to be the cause for the tensile stress. © 1995 American Institute of Physics.
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68.35.Fx Diffusion; interface formation
68.55.-a Thin film structure and morphology
68.60.Bs Mechanical and acoustical properties

Epitaxial electro‐optical SrxBa1−xNb2O6 films by single‐source plasma‐enhanced metalorganic chemical vapor deposition

L. D. Zhu, J. Zhao, F. Wang, Peter E. Norris, G. D. Fogarty, B. Steiner, P. Lu, B. Kear, S. B. Kang, B. Gallois, M. Sinclair, D. Dimos, and M. Cronin‐Golomb

Appl. Phys. Lett. 67, 1836 (1995); http://dx.doi.org/10.1063/1.115419 (3 pages) | Cited 8 times

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SrxBa1−xNb2O6 films have been epitaxially grown on MgO substrates by a single‐source plasma‐enhanced chemical vapor deposition (PE‐CVD). Exceptionally high quality of the epitaxial films was observed as indicated by high‐resolution synchrotron x‐ray diffraction imaging. The films exhibit waveguiding behavior with values of refractive index and the linear electro‐optic coefficient r51 close to those of bulk crystals. © 1995 American Institute of Physics.
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42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
68.55.-a Thin film structure and morphology
78.20.Jq Electro-optical effects

Effects of hydrogen addition and growth‐etch cycling on the oxy‐acetylene torch deposition of homoepitaxial diamond

R. A. Weimer, T. P. Thorpe, K. A. Snail, and C. E. Merzbacher

Appl. Phys. Lett. 67, 1839 (1995); http://dx.doi.org/10.1063/1.115420 (2 pages) | Cited 2 times

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Homoepitaxial diamond films were deposited onto (110) single crystal substrates using oxy‐acetylene torch deposition at a constant substrate temperature of 1150 °C. Growth‐etch cycling of the deposition increased the linear growth rates of the (100) and (111) faces by a factor of 2. The growth‐etch films were shown to be less transparent in the infrared than the reference depositions as determined by microfocus Fourier transform infrared spectroscopy. Using the growth‐etch technique, the growth rates of the (100), (111), and (110) faces decreased with increasing hydrogen addition to the combustion flame for hydrogen flow rates up to 50% of the acetylene flow rate. The additional hydrogen did not improve the growth‐etch films’ transparency. © 1995 American Institute of Physics.
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78.30.Hv Other nonmetallic inorganics
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Electron spin resonance observations of excimer‐laser‐induced paramagnetic centers in tellurite glasses

J. D. Prohaska, J. Li, J. S. Wang, and R. H. Bartram

Appl. Phys. Lett. 67, 1841 (1995); http://dx.doi.org/10.1063/1.115421 (3 pages) | Cited 1 time

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The ESR observations of three distinct paramagnetic centers in TeO2 glasses are reported. One center is intrinsic to the glass and the other two are induced by KrF‐excimer‐laser radiation. The intrinsic center with a broad ESR spectrum is tentatively identified as an oxygen‐associated hole center. One radiation‐induced center fades slowly at room temperature; its proposed structure is that of an electron trapped in a diffuse orbital associated with a modifier ion. The other radiation‐induced center is stable at room temperature and corresponds to the VO⋅ center observed in crystalline paratellurite. © 1995 American Institute of Physics.
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61.72.Hh Indirect evidence of dislocations and other defects (resistivity, slip, creep, strains, internal friction, EPR, NMR, etc.)
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)

Surface acoustic wave reflections from a proton exchanged dispersive dot array

Suneet Tuli, A. B. Bhattacharyya, and D. Fournier

Appl. Phys. Lett. 67, 1844 (1995); http://dx.doi.org/10.1063/1.115422 (3 pages) | Cited 1 time

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Proton‐exchanged (PE) regions in LiNbO3 create an invisible inhomogeneity that can be used as surface acoustic wave (SAW) reflectors similar to metallized overlays, implanted layers, or grooves. We report the detection of coherently reflected SAW, from a dispersive array of proton‐exchanged dot rows, by utilizing a sensitive interferometric heterodyne laser probe. © 1995 American Institute of Physics.
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77.65.Dq Acoustoelectric effects and surface acoustic waves (SAW) in piezoelectrics

Evidence of interstitial location of Er atoms implanted into silicon

A. Kozanecki, R. J. Wilson, B. J. Sealy, J. Kaczanowski, and L. Nowicki

Appl. Phys. Lett. 67, 1847 (1995); http://dx.doi.org/10.1063/1.115423 (3 pages) | Cited 8 times

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Silicon implanted with 2 MeV Er ions at 350 °C is studied by Rutherford backscattering and channeling spectroscopy. Angular scans through the 〈100〉, 〈111〉, and 〈110〉 axial channels were measured. The angular scan profiles of erbium, in particular flux peak in the 〈110〉 scan profile suggest that the implanted Er atoms are predominantly located in the middle of the 〈110〉 channel (the hexagonal interstitial site). Monte Carlo simulations have been performed for the assumed hexagonal interstitial location of Er atoms. They well reproduce the experimental data, giving additional evidence for the location of Er atoms in the middle of the 〈110〉 channel. © 1995 American Institute of Physics.
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61.72.uj III-V and II-VI semiconductors
61.80.Jh Ion radiation effects

Relationship between self‐organization and size of InAs islands on InP(001) grown by gas‐source molecular beam epitaxy

A. Ponchet, A. Le Corre, H. L’Haridon, B. Lambert, and S. Salaün

Appl. Phys. Lett. 67, 1850 (1995); http://dx.doi.org/10.1063/1.114353 (3 pages) | Cited 102 times

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Using the strained‐induced 2D–3D transition, InAs dots have been grown on InP(001) and examined by transmission electron microscopy. Two different modes of island size and spatial distribution have been identified. For deposit of 1.5 and 1.8 monolayers, the islands are about 7 nm high and randomly distributed. Above 2 monolayers, they are about five times smaller in volume and locally self‐organized, with a typical distance of 40 nm independent of the island density. It is suggested that the strong dependence of the island size on the total amount of deposited InAs is mainly due to long range interactions through the substrate. © 1995 American Institute of Physics.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.-a Thin film structure and morphology

Synthesis of oriented textured diamond films on silicon via hot filament chemical vapor deposition

Qijin Chen, Jie Yang, and Zhangda Lin

Appl. Phys. Lett. 67, 1853 (1995); http://dx.doi.org/10.1063/1.114354 (3 pages) | Cited 54 times

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Oriented diamond films were achieved on Si(001) and Si(111) substrates via hot filament chemical vapor deposition (HFCVD) with the orientation relationship of dia〈110〉//Si〈110〉 and dia(001)//Si(001) for Si(001), and of dia〈110〉//Si〈110〉 and dia(111)//Si(111) for Si(111). The substrates were negatively biased relative to the filament during the nucleation stage. The as‐grown films were characterized by scanning electron microscopy (SEM) and Raman spectroscopy. The role of negative bias is discussed in light of the differences between HFCVD and microwave plasma CVD. In conclusion, the importance of the electron emission from the diamond coating on the substrate holder is highlighted, while the ion bombardment is eliminated as a main factor based on our experiments. © 1995 American Institute of Physics.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

High quality InGaN films by atomic layer epitaxy

K. S. Boutros, F. G. McIntosh, J. C. Roberts, S. M. Bedair, E. L. Piner, and N. A. El‐Masry

Appl. Phys. Lett. 67, 1856 (1995); http://dx.doi.org/10.1063/1.114355 (3 pages) | Cited 27 times

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InxGa1−xN single‐crystal films were grown at 600–700 °C by atomic layer epitaxy (ALE). InGaN films with compositions of up to 27% indium were achieved. The full width at half‐maximum (FWHM) of the (0002) InxGa1−xN peak by double crystal x‐ray diffraction (DCXRD) was as small as 6 min, the lowest value reported for this ternary alloy. Strong photoluminescence band edge emission between 360 and 446 nm was observed at room temperature. These low temperature ALE grown films were achieved without the need to use excessive flows of the In organometallic source and thus demonstrate the potential for growth of this ternary alloy over the entire composition range. © 1995 American Institute of Physics.
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68.55.-a Thin film structure and morphology

Improved thermal stability of AlGaAs–GaAs quantum well heterostructures using a ‘‘blocking’’ Zn diffusion to reduce column‐III vacancies

M. R. Krames, A. D. Minervini, E. I. Chen, N. Holonyak, and J. E. Baker

Appl. Phys. Lett. 67, 1859 (1995); http://dx.doi.org/10.1063/1.114356 (3 pages)

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Data are presented on the reduction of layer intermixing (disordering) in AlGaAs–GaAs quantum well heterostructures (QWH) during high‐temperature anneals by an initial low‐temperature ‘‘blocking’’ Zn diffusion. Room‐temperature photoluminescence measurements of the increase in the lowest electron‐to‐heavy‐hole transition energy in the QW are used to characterize the extent of layer intermixing. Doped (C and Si) samples annealed (850 °C, 12 h) after a low‐temperature blocking Zn diffusion (480 °C) exhibit reductions in energy shift from ∼177 meV to as little as ∼18 meV. Similar effects are also observed, but to a lesser extent, for undoped samples. The improved thermal stability is attributed to a Zn‐diffusion induced reduction in the number of column‐III vacancies in the active layers and is confirmed by secondary‐ion mass spectroscopy measurements. © 1995 American Institute of Physics.
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66.30.J- Diffusion of impurities
68.35.Fx Diffusion; interface formation

Near‐field optical beam induced current measurements on heterostructures

M. S. Ünlü, B. B. Goldberg, W. D. Herzog, D. Sun, and E. Towe

Appl. Phys. Lett. 67, 1862 (1995); http://dx.doi.org/10.1063/1.114357 (3 pages) | Cited 29 times

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We report near‐field optical beam induced current (NOBIC) measurements on semiconductor quantum well (QW) structures. A subwavelength fiber tip is coupled with a tunable laser source and scanned over a sample surface. The induced photocurrent reveals the compositional profile of quantum structures. Semiconductor QW structures were designed and fabricated by molecular beam epitaxy (MBE) to study the wavelength dependence and resolution capability of NOBIC. We demonstrated that the resolution of this technique strongly depends on the aperture size. For aperture sizes that allow for coupling of evanescent fields from the tip into the semiconductor as propagating fields, the resolution strongly depends on the excitation wavelength due to the variation of the optical penetration depth. For smaller apertures, the optical field remains evanescent in the semiconductor and resolution is essentially independent of the wavelength. © 1995 American Institute of Physics.
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68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)
68.37.Ps Atomic force microscopy (AFM)
68.37.Rt Magnetic force microscopy (MFM)
68.37.Uv Near-field scanning microscopy and spectroscopy
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
73.50.Pz Photoconduction and photovoltaic effects

Growth of germanium‐carbon alloys on silicon substrates by molecular beam epitaxy

J. Kolodzey, P. A. O’Neil, S. Zhang, B. A. Orner, K. Roe, K. M. Unruh, C. P. Swann, M. M. Waite, and S. Ismat Shah

Appl. Phys. Lett. 67, 1865 (1995); http://dx.doi.org/10.1063/1.114358 (3 pages) | Cited 47 times

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See Also: Erratum

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Metastable Ge1−yCy alloys were grown by molecular beam epitaxy as homogeneous solid solutions having a diamond lattice structure. The substrates were (100) oriented Si wafers and the growth temperature was 600 °C. We report on measurements of the composition, structure, lattice constant, and optical absorption of the alloy layers. In thick relaxed layers, C atomic fractions up to 0.03 were obtained with a corresponding band gap of 0.875 eV. These alloys offer new opportunities for fundamental studies, and for the development of silicon‐based heterostructure devices. © 1995 American Institute of Physics.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

High‐power InGaN single‐quantum‐well‐structure blue and violet light‐emitting diodes

Shuji Nakamura, Masayuki Senoh, Naruhito Iwasa, and Shin‐ichi Nagahama

Appl. Phys. Lett. 67, 1868 (1995); http://dx.doi.org/10.1063/1.114359 (3 pages) | Cited 264 times

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High‐power blue and violet light‐emitting diodes (LEDs) based on III–V nitrides were grown by metalorganic chemical vapor deposition on sapphire substrates. As an active layer, the InGaN single‐quantum‐well‐structure was used. The violet LEDs produced 5.6 mW at 20 mA, with a sharp peak of light output at 405 nm, and exhibited an external quantum efficiency of 9.2%. The blue LEDs produced 4.8 mW at 20 mA and sharply peaked at 450 nm, corresponding to an external quantum efficiency of 8.7%. These values of the output power and the quantum efficiencies are the highest ever reported for violet and blue LEDs. © 1995 American Institute of Physics.
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78.60.Fi Electroluminescence
85.60.Jb Light-emitting devices
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