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22 Apr 1996

Volume 68, Issue 17, pp. 2317-2455

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Voltage‐tunable‐color multilayer organic light emitting diode

J. Kalinowski, P. Di Marco, M. Cocchi, V. Fattori, N. Camaioni, and J. Duff

Appl. Phys. Lett. 68, 2317 (1996); http://dx.doi.org/10.1063/1.115843 (3 pages) | Cited 46 times

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Organic electroluminescent diodes with a double‐heterostructure of indium‐tin‐oxide (ITO) substrate/aromatic diamine (TPD)/8‐hydroxyquinoline aluminum (Alq3)/perylene bisimide pigment (PBP)/Mg/Ag have been fabricated by successive vapor deposition. Their electroluminescence (EL) for thin layers of PBP varies from the orange dominated by the red emission of PBP to greenish‐yellow with a strong contribution of the green emission of Alq3 as voltage increases. The relative contribution of the red emission increases with increasing voltage for the structures with thick PBP layers. The tuning of the EL color is explained in terms of electric field‐induced quenching of excited states and voltage evolution of the recombination zone in PBP. © 1996 American Institute of Physics.
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85.60.Jb Light-emitting devices
78.66.Qn Polymers; organic compounds
78.60.Fi Electroluminescence

Resistless, area‐selective ultrashallow P+/N junction fabrication using projection gas immersion laser doping

K.‐Josef Kramer, Somit Talwar, Isabella T. Lewis, John E. Davison, Kenneth A. Williams, Keith A. Benton, and Kurt H. Weiner

Appl. Phys. Lett. 68, 2320 (1996); http://dx.doi.org/10.1063/1.115844 (3 pages) | Cited 8 times

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The selective fabrication of ultrashallow p+/n junctions in silicon using projection gas immersion laser doping is reported. The method offers substantial improvement and simplification in junction formation to integrated circuit manufacturers, since several processing steps required for conventional doping techniques like ion implantation are eliminated. Spatially selective incorporation of boron into silicon without the use of any masking layer on the wafer surface is achieved. A pulsed excimer laser beam is patterned using a chromeless reticle and the pattern is transferred through a projection system onto a wafer that is kept in a BF3 dopant gas ambient. The depth of the fabricated junctions is 60 nm with a surface concentration of 5×1019 cm−3. The vertical and lateral distribution of boron in silicon after patterned laser processing is investigated using secondary ion mass spectroscopy (SIMS) and time‐of‐flight SIMS (ToF‐SIMS). Vertical and lateral dopant profiles are steep and clearly resolved. © 1996 American Institute of Physics.
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85.40.Ry Impurity doping, diffusion and ion implantation technology

Pulsed anodic etching: An effective method of preparing light‐emitting porous silicon

Xiao‐yuan Hou, Hong‐lei Fan, Lei Xu, Fu‐long Zhang, Min‐qian Li, Ming‐ren Yu, and Xun Wang

Appl. Phys. Lett. 68, 2323 (1996); http://dx.doi.org/10.1063/1.115845 (3 pages) | Cited 34 times

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A pulsed anodic etching method is developed to prepare light‐emitting porous silicon. Under the same equivalent etching condition, pulsed etching can yield a more uniform porous silicon film with stronger photoluminescence intensity than the film prepared by ordinary dc etching. The atomic force microscopic observation shows that the porous silicon surface prepared by pulsed etching contains more widely separated Si columns but with steeper sidewalls, which are believed to result in the improvement of quantum confinement. The thickness of pulse etched porous silicon film is found to be much larger than that of a dc etched sample. © 1996 American Institute of Physics.
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81.65.Cf Surface cleaning, etching, patterning
81.05.Rm Porous materials; granular materials

Waveguiding in (quantum) wire structures: Impact on the polarization characteristics and the slope of the optical gain

G. Lehr, V. Härle, F. Scholz, and H. Schweizer

Appl. Phys. Lett. 68, 2326 (1996); http://dx.doi.org/10.1063/1.115846 (3 pages)

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This work discusses the role of quantum wires as electromagnetic waveguides. The optical gain of buried InGaAs/In(GaAs)P wire structures is investigated as a function of the wire width. We find that the relative contribution of the light and heavy hole transition as well as the optical polarization of the gain are strongly dependent on the wire width. This corresponds to the behavior expected as a result of quantum confinement. Based on calculations of the waveguiding behavior of the wires, however, we attribute these effects to changes of the waveguide properties rather than to quantum confinement effects of the carriers. © 1996 American Institute of Physics.
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78.66.Fd III-V semiconductors
42.79.Gn Optical waveguides and couplers

Vanishing optical isolation barrier in double ion‐implanted lithium niobate waveguide

S. S. Sarkisov, E. K. Williams, D. Ila, P. Venkateswarlu, and D. B. Poker

Appl. Phys. Lett. 68, 2329 (1996); http://dx.doi.org/10.1063/1.115847 (3 pages) | Cited 6 times

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Isolation properties at different propagation directions have been studied for an optical barrier between two superposed planar waveguides produced by MeV He+ implantation in LiNbO3. The barrier exists while the modes of the double structure propagate along the optic axis. The spacing between the modes measured with a prism coupler features efficiently isolated waveguides. The barrier ‘‘vanishes’’ when the directional angle between an extraordinary wave and the optic axis exceeds 50°. In this case the mode spacing shows strong coupling between the waveguides that makes the double structure similar to a single waveguide with double thickness. © 1996 American Institute of Physics.
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42.79.Gn Optical waveguides and couplers
61.80.Jh Ion radiation effects

ZnSe‐based birefringent waveguide as Pockels retarder in the blue‐green spectral range

H. Babucke, P. Thiele, T. Prasse, M. Rabe, and F. Henneberger

Appl. Phys. Lett. 68, 2332 (1996); http://dx.doi.org/10.1063/1.115848 (3 pages) | Cited 1 time

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Electro‐refractive modulation in the blue‐green spectral range is demonstrated in strained, MBE‐grown ZnSe waveguides with cladding layers of ZnMnSe on n‐GaAs substrates. Utilizing the Pockels effect in Schottky‐contacted structures with built‐in birefringence, a contrast ratio better than 80:1 at 2.485 eV is achieved. The rise time of (4.7±0.5) ns is RC limited. © 1996 American Institute of Physics.
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42.79.Hp Optical processors, correlators, and modulators
42.65.Pc Optical bistability, multistability, and switching, including local field effects

New method for in situ control of Bragg reflector fabrication

S. Callard, A. Gagnaire, and J. Joseph

Appl. Phys. Lett. 68, 2335 (1996); http://dx.doi.org/10.1063/1.115849 (2 pages) | Cited 2 times

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A simple, robust method for real time monitoring of Bragg reflector layer thickness is described. The method is based on the choice of the appropriate ellipsometric measurement wavelength to control the deposition of the top layer. This method requires no information on the underlying structure. To evaluate the method, Bragg reflectors were developed with SiO2 and SiNx stacks grown by electron cyclotron resonance plasma chemical vapor deposition. Reflectivity measurements performed on these reflectors confirm the reproducibility and accuracy of the method. © 1996 American Institute of Physics.
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81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
78.66.-w Optical properties of specific thin films

Near‐infrared contact mode collection near‐field optical and normal force microscopy of modulated multiple quantum well lasers

U. Ben‐Ami, N. Tessler, N. Ben‐Ami, R. Nagar, G. Fish, K. Lieberman, G. Eisenstein, A. Lewis, J. M. Nielsen, and A. Møeller‐Larsen

Appl. Phys. Lett. 68, 2337 (1996); http://dx.doi.org/10.1063/1.115850 (3 pages) | Cited 8 times

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Contact near‐field and far‐field imaging of multiple quantum well (MQW) structures emitting at 1.54 μm is reported using bent normal force/near‐field optical elements for simultaneous imaging of the light distribution, topography, and modulation of the normal force signal with laser modulation. Excellent registration and correlation of each of these images is reported. Alterations in the distribution of the light emission in going from the near to the far‐field is detected in agreement with theoretical deductions. Nonetheless, differences are also noted in this light distribution from standard understandings. © 1996 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
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

Role of heterointerface on enhancement of no‐phonon luminescence in Si‐based neighboring confinement structure

N. Usami, Y. Shiraki, and S. Fukatsu

Appl. Phys. Lett. 68, 2340 (1996); http://dx.doi.org/10.1063/1.115851 (3 pages) | Cited 13 times

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The origin of the no‐phonon (NP) luminescence enhancement was explored in Si‐based neighboring confinement structures (NSCs). Post growth annealing was found to lead to quenching of the NP line. Time‐resolved photoluminescence study clarified that the radiative lifetime of the annealed sample increases with increasing temperature, while that of the as‐grown sample shows no significant change at low temperatures (<40 K). These results are reasonably explained by considering that ‘‘in‐plane’’ exciton at the heterointerface is the controlling mechanism for the NP enhancement which is observed at low temperatures in the as‐grown NCS. © 1996 American Institute of Physics.
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78.66.Li Other semiconductors
78.55.Cr III-V semiconductors

Heat diffusivity of La1−xCaxMnO3 epitaxial layers

J. Liebe, E. Kraus, L. Haupt, P. Mandal, K. Bärner, and R. v. Helmolt

Appl. Phys. Lett. 68, 2343 (1996); http://dx.doi.org/10.1063/1.115852 (3 pages) | Cited 6 times

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The Seebeck effect and the thermal diffusivity of La0.67Ca0.33MnO3−δ were investigated in the temperature range 35<T<300 K and in particular in the regime of the high magnetoresistance and maximum resistivity ρmax. We find a sign change of the thermoelectric power S(T) and a step in heat conductivity near ρmax which we attribute to a temperature‐induced metal–insulator transition at about 80 K, suggesting that the large giant magnetoresistance found in these substances is due to a field‐induced metal–insulator transition. © 1996 American Institute of Physics.
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71.30.+h Metal-insulator transitions and other electronic transitions
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
72.15.Eb Electrical and thermal conduction in crystalline metals and alloys

Polyquinoxaline as an excellent electron injecting material for electroluminescent device

Takashi Fukuda, Takaki Kanbara, Takakazu Yamamoto, Ken Ishikawa, Hideo Takezoe, and Atsuo Fukuda

Appl. Phys. Lett. 68, 2346 (1996); http://dx.doi.org/10.1063/1.115853 (3 pages) | Cited 37 times

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Electron injecting properties have been studied for one of polyquinoxaline (PQx) derivatives. PQx was clarified to be an excellent electron injecting material for electroluminescent (EL) device because it has many advantageous properties such as high electron affinity, good thermal stability, good processability, and sufficiently low refractive index. On the other hand, since poly(p‐phenylenevinylene) (PPV) was known as a good hole injecting material, an EL device with ITO/PPV/PQx/metal type structure was suggested. It was shown that the quantum efficiency of the cell was higher than that of ITO/PPV/metal cell. Related physical and optical properties of PQx derivatives are also investigated. © 1996 American Institute of Physics.
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78.66.Qn Polymers; organic compounds
78.60.Fi Electroluminescence
85.60.Jb Light-emitting devices

Surface modification of silicon (111) by annealing at high temperature in hydrogen

Lei Zhong, Ryuji Takeda, Koji Izunome, Yoshiaki Matsushita, Yoshiro Aiba, Junichi Matsushita, Jun Yoshikawa, Kenro Hayashi, Hiroshi Shirai, and Hiroyoki Saito

Appl. Phys. Lett. 68, 2349 (1996); http://dx.doi.org/10.1063/1.115854 (3 pages) | Cited 1 time

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A vicinal silicon (111) surface exhibits well defined single steps after being annealed at 1200 °C in hydrogen, which is in sharp contrast with step bunches featuring the surface annealed in argon. As a temporary explanation for its ability to unzip the step bunches, we suggest that hydrogen destroys the faulted triangles of a [112] step, eliminates this kind of step, and eventually leaves the single [112] steps alone behind on the surface. © 1996 American Institute of Physics.
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81.65.-b Surface treatments

Observation of Si in SiC composite fibers: A micro‐Raman investigation

Jeongyong Kim, Spirit Tlali, Howard E. Jackson, James E. Webb, and Raj N. Singh

Appl. Phys. Lett. 68, 2352 (1996); http://dx.doi.org/10.1063/1.115855 (3 pages) | Cited 3 times

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The chemical composition and microstructure of SiC composite fibers were studied by spatially resolved Raman spectroscopy. The spectra display a strong peak in the outer SiC layer identified as a Si signature and thus provide direct evidence of the presence of excess Si in the fiber composites. The Si crystallite size as well as the stress in the Si were estimated. Excess silicon has been previously suggested as the cause of the unusual creep and the anomalous thermal expansion behavior of these composites at high temperatures. © 1996 American Institute of Physics.
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78.30.Hv Other nonmetallic inorganics
61.43.Fs Glasses

Measurement of index of refraction of InxAl1−xAs epitaxial layer using in situ laser reflectometry

Jong‐Hyeob Baek, Bun Lee, Sung Woo Choi, Jin Hong Lee, and El‐Hang Lee

Appl. Phys. Lett. 68, 2355 (1996); http://dx.doi.org/10.1063/1.115856 (3 pages) | Cited 8 times

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We report the application of in situ laser reflectometry in measuring index of refraction and other optical properties of InxAl1−xAs (0≤x≤1) epitaxial layers grown on GaAs substrates by low‐pressure metal‐organic chemical vapor deposition method. Two different lasers were used: One was a He–Ne laser operating at 0.6328 μm and the other was a single mode distributed‐feedback (DFB) laser diode operating at 1.530 μm. The two laser beams were simultaneously directed on the growing layer at an angle of 71° from the surface normal. The oscillatory signals showed a variety of patterns depending on the index of refraction of the epitaxial layer of InxAl1−xAs (0≤x≤1). The initial oscillatory signal pattern was found to be reversed at the composition of x=0.75, where the index of refraction of the InxAl1−xAs layer is the same as that of the GaAs substrate. The absorption coefficients and indices of refraction of the InxAl1−xAs epitaxial layers were obtained for the entire range of composition at the growth temperature of 535 °C by in situ laser reflectometry. © 1996 American Institute of Physics.
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78.66.Fd III-V semiconductors
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Formation and observation of 50 nm polarized domains in PbZr1−xTixO3 thin film using scanning probe microscope

T. Hidaka, T. Maruyama, M. Saitoh, N. Mikoshiba, M. Shimizu, T. Shiosaki, L. A. Wills, R. Hiskes, S. A. Dicarolis, and Jun Amano

Appl. Phys. Lett. 68, 2358 (1996); http://dx.doi.org/10.1063/1.115857 (2 pages) | Cited 114 times

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Nanometer size polarized domains were written in a PbZr1−xTixO3 (PZT) thin film using an atomic force microscope (AFM) and the relationship between the polarized domain and the grain of the film was investigated. The polarized domain was formed by applying a pulse voltage to the ferroelectric PZT thin film through a conductive AFM tip. The polarized domain structure was observed by imaging the piezoelectric‐induced surface vibration by an AFM with an ac voltage applied between the tip and the bottom electrode of a sample. The polarized domains with a diameter of 50 nm were written within a single grain. © 1996 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

Biaxial alignment of TiN films prepared by ion beam assisted deposition

J. W. Gerlach, U. Preckwinkel, H. Wengenmair, T. Kraus, and B. Rauschenbach

Appl. Phys. Lett. 68, 2360 (1996); http://dx.doi.org/10.1063/1.115858 (3 pages) | Cited 16 times

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The biaxial alignment of TiN on Si(111) films prepared by nitrogen ion beam assisted deposition at room temperature was studied. By reactive deposition within a nitrogen environment a preferred {111} orientation was obtained the growing TiN crystallites. In contrast, a nitrogen ion bombardment perpendicular to the surface of the substrate during deposition causes an {001} alignment of the crystallites. A 55° ion beam incidence produces both {111}‐orientation relative to the surface and {100}‐orientation relative to the ion beam. This results in a totally fixed orientation of the crystallites. Simultaneous UV‐light illumination during ion bombardment promotes a uniformly oriented growth. © 1996 American Institute of Physics.
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81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
68.55.-a Thin film structure and morphology

Quasi‐one‐dimensional CaF2 islands formed on Si(001) by molecular beam epitaxy

D. Loretto, F. M. Ross, and C. A. Lucas

Appl. Phys. Lett. 68, 2363 (1996); http://dx.doi.org/10.1063/1.115859 (3 pages) | Cited 16 times

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Quasi‐one‐dimensional CaF2 islands, 5–10 nm in both width and height and several μm in length, have been grown on Si(001) by molecular beam epitaxy. Using conventional and high resolution transmission electron microscopy we show that the islands grow in two symmetry‐equivalent, {011} orientations and are bounded by {111} facets. The unusual island morphology is attributed to a low density of nucleation sites, the small lattice mismatch, and the anisotropic CaF2 surface energy. © 1996 American Institute of Physics.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
81.07.-b Nanoscale materials and structures: fabrication and characterization
81.16.-c Methods of micro- and nanofabrication and processing
85.35.-p Nanoelectronic devices

Dry oxidation mechanisms of thin dielectric films formed under N2O using isotopic tracing methods

J.‐J. Ganem, S. Rigo, I. Trimaille, I. J. R. Baumvol, and F. C. Stedile

Appl. Phys. Lett. 68, 2366 (1996); http://dx.doi.org/10.1063/1.116135 (3 pages) | Cited 14 times

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We investigated the mechanisms of thermal reoxidation in dry O2 of silicon oxynitride films prepared by processing Si(100) wafers in a rapid thermal furnace in a pure nitrous oxide (N2O) ambient, using isotopic tracing of oxygen and nitrogen. Standard nuclear reaction analyses for the measurement of the total amounts of the different isotopes, and very narrow resonant nuclear reactions for high resolution (1 nm) depth profiling of these elements were used. The silicon oxynitride films grown in pure 15N216O were 8‐nm thick, with a small amount of nitrogen localized near the interfacial region. Under reoxidation in dry 18O2, the thickness of the dielectric film increased while a pronounced isotopic exchange took place between the 18O from the gas and the 16O from the film, as well as a significant loss of 15N. This is in contrast with the reoxidation in dry O2 of pure SiO2 films, where the oxygen exchange is rather small as compared to that observed in the present case. © 1996 American Institute of Physics.
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81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
81.65.Mq Oxidation

Local field in ferroelectrics: Direct measurements with an optical probe

L. M. Blinov, K. A. Verkhovskaya, S. P. Palto, and A. V. Sorokin

Appl. Phys. Lett. 68, 2369 (1996); http://dx.doi.org/10.1063/1.116136 (3 pages) | Cited 3 times

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A local electric field, which acts on an individual molecule incorporated in a ferroelectric matrix, has been measured. For this purpose, absorption spectra of electrochromic dyes with well‐defined properties of the ground and excited states were measured in a ferroelectric copolymer matrix above and below the phase transition temperature. The local electric field, which is due to the spontaneous polarization, has been evaluated from a spectral shift of the absorption maximum at the transition from the paraelectric to the ferroelectric phase. © 1996 American Institute of Physics.
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77.55.-g Dielectric thin films
77.80.-e Ferroelectricity and antiferroelectricity
77.84.-s Dielectric, piezoelectric, ferroelectric, and antiferroelectric materials

The effect of stress on the resistivity of submicron aluminum lines

N. L. Beverly, G. B. Alers, and J. A. Prybyla

Appl. Phys. Lett. 68, 2372 (1996); http://dx.doi.org/10.1063/1.116137 (3 pages) | Cited 3 times

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The stress coefficient of resistivity (piezoresistance coefficient) of passivated submicron Al‐Cu lines was determined using a wafer‐bending technique. This coefficient is significant for the interpretation of early resistance changes in reliability lifetime measurements. At room temperature the effect of stress on the resistivity of the lines is negligible. From 110 to 200 °C the piezoresistance coefficient is roughly constant at (Δρ/ρ)/Δσ∼1.2×10−5 MPa−1. Resistance changes associated with stress relaxation in the vicinity of a stress‐induced void will be discussed. © 1996 American Institute of Physics.
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77.65.-j Piezoelectricity and electromechanical effects
62.40.+i Anelasticity, internal friction, stress relaxation, and mechanical resonances

Formation of deep thermal donors in heat‐treated Czochralski silicon

V. V. Emtsev, G. A. Oganesyan, and K. Schmalz

Appl. Phys. Lett. 68, 2375 (1996); http://dx.doi.org/10.1063/1.116138 (3 pages) | Cited 4 times

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Formation of new donors in Czochralski silicon (Cz‐Si) at temperatures T≥600 °C was studied. The contribution of deep donors was separated from those of other donor families with shallower states and in this way the formation kinetics of deep thermal donors was established. The results obtained make it possible to attribute these donor states at ≊EC−0.1 eV to ≊EC−0.25 eV to ribbonlike defects. Variations in the cross section of A‐center formation under gamma irradiation of heat‐treated Cz‐Si were found to correlate with formation of deep thermal donors. © 1996 American Institute of Physics.
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71.55.Cn Elemental semiconductors
61.72.Cc Kinetics of defect formation and annealing

Cathodoluminescence and writing of optical patterns on porous silicon by scanning electron microscopy

A. Bruska, A. Chernook, St. Schulze, and M. Hietschold

Appl. Phys. Lett. 68, 2378 (1996); http://dx.doi.org/10.1063/1.116139 (2 pages) | Cited 7 times

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Cathodoluminescence (CL) imaging has been used to characterize thin layers of porous silicon. A system for cathodoluminescence (CL) mapping is built in a scanning electron microscopy and able to detect radiation from 350 to about 550 nm. The whole system is operated under a computer control giving the possibility to perform imaging in both secondary electron detection usual for scanning electron microscopy (SEM) and the cathodoluminescence mode. We have mapped inhomogeneous CL from the sample surface and modified the CL intensity by irradiation of the sample with the electron beam. A sample of porous silicon can be easily irreversibly patterned on a micrometer scale using such a focused controlled irradiation. Possible applications in optoelectronics will be discussed. © 1996 American Institute of Physics.
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81.07.-b Nanoscale materials and structures: fabrication and characterization
81.16.-c Methods of micro- and nanofabrication and processing
85.35.-p Nanoelectronic devices
78.60.Hk Cathodoluminescence, ionoluminescence

Deposition and extensive light soaking of highly pure hydrogenated amorphous silicon

Toshihiro Kamei, Nobuhiro Hata, Akihisa Matsuda, Toyoshi Uchiyama, Shigeru Amano, Kazuyoshi Tsukamoto, Yoshiaki Yoshioka, and Takashi Hirao

Appl. Phys. Lett. 68, 2380 (1996); http://dx.doi.org/10.1063/1.116140 (3 pages) | Cited 19 times

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We have developed an ultrahigh vacuum plasma‐enhanced chemical‐vapor deposition system, and deposited high‐purity device‐quality hydrogenated amorphous silicon films. High sensitivity secondary ion mass spectrometry measurements show that impurity contents in the bulk of the present films are reduced to 2×1015 cm−3 for O, 7–10×1015 cm−3 for C, and 5×1014 cm−3 for N; these impurities are normally present at fairly high levels. Nevertheless, extensive light soaking of the films resulted in a defect density as high as 5×1017 cm−3, which is well above the impurity content. This result excludes those models of photoinduced degradation that postulate one‐to‐one correlation between light‐induced defects and O, C, or N impurity atoms. © 1996 American Institute of Physics.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Polarization effect in light emitting diodes with ordered GaInP active layers

E. Greger, K. H. Gulden, P. Riel, H. P. Schweizer, M. Moser, G. Schmiedel, P. Kiesel, and G. H. Döhler

Appl. Phys. Lett. 68, 2383 (1996); http://dx.doi.org/10.1063/1.116141 (3 pages) | Cited 20 times

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We report on polarization effects in surface emitting light emitting diodes based on p‐i‐n AlGaInP/GaInP double heterostructures grown by metal organic vapor phase epitaxy. Devices with an ordered GaInP active layer show polarized light output with a ratio of 4:3 for polarization along the [011] and [011] crystal direction, respectively. This polarization is nearly independent of diode current and mesa geometry, but is not observed if disordered GaInP active layers are used. The effect is considered to be an important means for polarization control in vertical cavity surface emitting lasers. © 1996 American Institute of Physics.
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85.60.Jb Light-emitting devices
78.60.Fi Electroluminescence

Observation of temperature‐insensitive emission wavelength in GaInAs strained multiple‐quantum‐wire heterostructures

D. E. Wohlert, S. T. Chou, A. C. Chen, K. Y. Cheng, and K. C. Hsieh

Appl. Phys. Lett. 68, 2386 (1996); http://dx.doi.org/10.1063/1.116142 (3 pages) | Cited 25 times

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We report on the photoluminescence (PL) properties of GaxIn1−xAs strained multiple‐quantum‐wire (MQWR) heterostructures formed in situ by the strain‐induced lateral‐layer ordering (SILO) process. Samples with moderately strained MQWR active regions demonstrate a negligible variance in emitted PL spectra with respect to temperature. The net temperature dependence of PL wavelength for these samples is less than 0.1 Å/°C between 77 and 300 K. For MQWR samples with stronger lateral composition modulation, the PL peak wavelength blue shifts with increasing temperature. The SILO process induced multiaxial strain in the (GaAs)2/(InAs)2.2 short‐period‐superlattice active region is responsible for this temperature insensitivity and blueshift of PL wavelength with temperature. © 1996 American Institute of Physics.
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78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
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