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24 Apr 1989

Volume 54, Issue 17, pp. 1607-1705

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Spatially distributed gains in semiconductor lasers

Y. Le Grand and A. Le Floch

Appl. Phys. Lett. 54, 1607 (1989); http://dx.doi.org/10.1063/1.101321 (3 pages) | Cited 2 times

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A careful analysis of the gain using the amplified spontaneous emission in semiconductor lasers concludes that there is a spatial distribution of the gain. A twofold distribution is observed in the planes parallel and perpendicular to the junction with different decreasing variations from the laser axis to the edge of the radiation lobe. Collecting the entire emitted light beam gives usually too low gain values. Gain measurements restricted to the region around the laser beam axis lead to an improvement of the gain value determination being within 96% of the actual value determined by the laser threshold.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation

Frequency chirped short pulse amplification in inhomogeneously broadened XeCl gain media

Fumihiko Kannari and Minoru Obara

Appl. Phys. Lett. 54, 1610 (1989); http://dx.doi.org/10.1063/1.101322 (3 pages) | Cited 5 times

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The application of a frequency chirped pulse amplification sheme for XeCl excimer lasers is theoretically evaluated by solving the Maxwell–Bloch equations [A. Icsevgi and W. E. Lamb, Jr., Phys. Rev. 185, 517 (1969)]. The calculated effective saturation energies for subpicosecond nonchirped laser pulses are much higher than the values that have been obtained experimentally. If this evidence indicates that optical nonlinear effects at high laser intensities are reducing the extraction energy, frequency chirped amplification followed by pulse compression, as demonstrated with solid‐state lasers, is also useful with XeCl lasers. This helps to reduce the peak laser intensity and increase the extraction energy.
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42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation
42.55.Lt Gas lasers including excimer and metal-vapor lasers
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.65.Re Ultrafast processes; optical pulse generation and pulse compression

Broadband (6 GHz) GaAs/AlGaAs electro‐optic modulator with low drive power

R. G. Walker

Appl. Phys. Lett. 54, 1613 (1989); http://dx.doi.org/10.1063/1.101323 (3 pages) | Cited 1 time

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A GaAs/AlGaAs Mach–Zehnder modulator using a push‐pull drive configuration is reported. The bandwidth/drive‐voltage figure of merit is approximately double that of an equivalent single‐sided device and is the highest reported for any non‐traveling‐wave structure. Vπ is 9 V at 1150 nm. Using unterminated drive a bandwidth of 6.25 GHz is achieved.
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42.79.Hp Optical processors, correlators, and modulators
42.82.-m Integrated optics
42.79.Ta Optical computers, logic elements, interconnects, switches; neural networks
78.20.Jq Electro-optical effects

Novel guided‐wave acousto‐optic frequency shifting scheme using Bragg diffractions in cascade

C. S. Tsai and Z. Y. Cheng

Appl. Phys. Lett. 54, 1616 (1989); http://dx.doi.org/10.1063/1.101392 (3 pages) | Cited 2 times

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A novel integrated optical frequency shifter that utilizes guided‐wave acousto‐optic Bragg diffractions in cascade from two tilted and counterpropagating surface acoustic waves is reported. The doubly and frequency‐shifted diffracted light propagates in a fixed direction, but spatially resolved from the incident light, irrespective of the magnitude of frequency tuning. A preliminary device fabricated in a Y‐cut LiNbO3 planar waveguide has demonstrated a gigahertz frequency shift, a tunable bandwidth of 165 MHz, and other desirable characteristics at the optical wavelength of 0.63 μm. These preliminary results suggest that a compact integrated acousto‐optic frequency shifter module may be realized in a common LiNbO3 substrate 0.2×10×1.5 cm3 in size.
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42.79.Gn Optical waveguides and couplers
78.20.hb Piezo-optical, elasto-optical, acousto-optical, and photoelastic effects

Optical third‐harmonic generation from poly‐(2,5‐dimethoxy p‐phenylene vinylene) thin film

Toshikuni Kaino, Hideki Kobayashi, Ken‐ichi Kubodera, Takashi Kurihara, Shogo Saito, Tetsuo Tsutsui, and Shizuo Tokito

Appl. Phys. Lett. 54, 1619 (1989); http://dx.doi.org/10.1063/1.101393 (3 pages) | Cited 18 times

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Third‐harmonic generation has been measured in poly(2,5‐dimethoxy p‐phenylene vinylene) thin film. The third‐order optical susceptibility, χ(3), was evaluated to be 5.4×10−11 esu at 1.85 μm wavelength. This χ(3) value is about one order higher than that for poly(p‐phenylene vinylene) and almost the same value as for poly(n‐BCMU diacetylene) which possesses the highest χ(3) value among processible (solvent castable) polymeric materials.
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42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
78.66.Qn Polymers; organic compounds
42.70.-a Optical materials

Electro‐optic sideband generation at 72 GHz

R. Kallenbach, B. Scheumann, C. Zimmermann, D. Meschede, and T. W. Hänsch

Appl. Phys. Lett. 54, 1622 (1989); http://dx.doi.org/10.1063/1.101324 (3 pages) | Cited 6 times

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Sidebands are observed at 72 GHz off an optical carrier at 633 nm. The laser beam is phase modulated in a LiNbO3 crystal which is exposed to a mm‐wave field inside a Fabry–Perot resonator. Under optimum phase‐matching conditions we obtain a modulation index of 5% derived from 200 mW microwave power. Phase matching is obtained by guiding the light beam on a zig‐zag path under internal total reflections. For this unconventional type of phase matching, the optical wave fronts travel at twice the speed of the modulating wave along the resonator axis.
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42.79.Hp Optical processors, correlators, and modulators
78.20.Jq Electro-optical effects
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation

Diode laser pumped blue‐light source at 473 nm using intracavity frequency doubling of a 946 nm Nd:YAG laser

W. P. Risk, R. Pon, and W. Lenth

Appl. Phys. Lett. 54, 1625 (1989); http://dx.doi.org/10.1063/1.101394 (3 pages) | Cited 19 times

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Using intracavity frequency doubling of a diode laser pumped 946 nm Nd:YAG laser, 3.1 mW of blue output power at 473 nm was obtained. Angle‐tuned, type‐I frequency doubling in potassium niobate was employed, and both the KNbO3 and Nd:YAG crystals were used at room temperature.
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42.60.Fc Modulation, tuning, and mode locking
42.55.Rz Doped-insulator lasers and other solid state lasers
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation

Quick and simple method to measure third‐order nonlinear optical properties of dye‐doped polymer films

M. G. Kuzyk and C. W. Dirk

Appl. Phys. Lett. 54, 1628 (1989); http://dx.doi.org/10.1063/1.101376 (3 pages) | Cited 23 times

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Quadratic phase modulation is used to measure the electronic third‐order nonlinear optical susceptibility of thin polymer film solid solutions of organic dyes. This simple technique is shown to provide quick measurements of the χ(3)1133 component of the third‐order optical susceptibility. The measured quadratic electro‐optic coefficient of 7.5 wt. % (2.5 mol %) of a dicyanovinyl azo dye in poly(methyl methacrylate) (PMMA) is 4.4×10−21 m2/V2, which corresponds to a direct current Kerr coefficient of 1.4×10−11 esu. The electronic and orientational mechanisms, whose response times are faster than 30 ps, are discussed.
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78.66.Qn Polymers; organic compounds
42.70.-a Optical materials
42.65.-k Nonlinear optics

Selective area laser photodeposition of transparent conductive SnO2 films

R. R. Kunz, M. Rothschild, and D. J. Ehrlich

Appl. Phys. Lett. 54, 1631 (1989); http://dx.doi.org/10.1063/1.101395 (3 pages) | Cited 10 times

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The deposition of SnO2 films has been demonstrated using an ArF (193 nm) excimer laser to drive the photochemical reactions of mixed SnCl4 and N2 O vapors. Without any annealing, films 100 nm thick grown on room‐temperature substrates have resistivities as low as 0.04 Ω cm. The optical band gap of 3.20 eV and transmission cutoff wavelength of 330 nm compare favorably with the best films obtained using alternate higher temperature techniques. Subsequent annealing does not increase the film’s conductivity. Selective area growth of 10‐μm‐wide lines has been performed using proximity printing. The maximum temperature excursion during the laser pulse is estimated to be 300–400 °C.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
73.61.Ng Insulators
78.66.-w Optical properties of specific thin films
82.50.Bc Processes caused by infrared radiation
82.50.Hp Processes caused by visible and UV light

Nonplanar quantum well heterostructure window laser

R. P. Bryan, L. M. Miller, T. M. Cockerill, and J. J. Coleman

Appl. Phys. Lett. 54, 1634 (1989); http://dx.doi.org/10.1063/1.101307 (3 pages) | Cited 3 times

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Data are presented on a nonplanar graded barrier quantum well heterostructure window laser formed by a single metalorganic chemical vapor deposition (MOCVD) growth. By utilizing a selectively etched substrate, a transparent window region is formed in the vicinity of the facets thereby relaxing the maximum power limit imposed by catastrophic optical degradation. The ultimate output power available from such devices is approximately 50% higher than from devices with the same structure but grown on unetched substrates. The processing required for device fabrication is minimized by taking advantage of the properties of MOCVD growth on nonplanar substrates.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation
42.60.By Design of specific laser systems

Dye lasers generating two wavelengths simultaneously with a large wavelength separation

Kazuhito Ishikawa, Shinzo Muto, and Hidenori Matsuzawa

Appl. Phys. Lett. 54, 1637 (1989); http://dx.doi.org/10.1063/1.101308 (2 pages) | Cited 2 times

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A new type of dye laser which was pumped with N2 lasers and which generated two wavelengths simultaneously with separation in wavelength as much as 170 nm was shown experimentally. The laser cavity consisted of an output mirror, a grating, two dye cells containing different dye solutions, and a liquid prism having a small top angle (5° or 10°). Farther separation in wavelength is achievable when combinations of dyes and a prism of a larger top angle are chosen.
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42.60.Fc Modulation, tuning, and mode locking
42.55.Mv Dye lasers
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.60.By Design of specific laser systems

Restricted aperture acoustic microscope lens for Rayleigh wave imaging

D. A. Davids, P. Y. Wu, and D. Chizhik

Appl. Phys. Lett. 54, 1639 (1989); http://dx.doi.org/10.1063/1.101309 (3 pages) | Cited 3 times

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The performance of an acoustic microscope lens is reported that permits both Rayleigh wave velocity measurement of anisotropic media as well as raster‐scanned imaging. The lens surface is spherical and uses a circular p‐wave transducer; however, an acoustic absorbing layer is applied to the spherical surface in order to limit the angular range over which Rayleigh waves are launched. When operated at 50 MHz, a lens having a slot‐like aperture of 0.8 mm width permits measurement of VR (θ) of y‐cut quartz with a maximum error of less than 2%. The same system employed in imaging provides spatial resolution of about one wavelength in a direction parallel to the axis of the slot and between two and three wavelengths in the perpendicular direction.
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43.58.Ls Acoustical lenses and microscopes
43.35.Sx Acoustooptical effects, optoacoustics, acoustical visualization, acoustical microscopy, and acoustical holography

Production of disilane and silyl sticking coefficients during plasma‐enhanced chemical vapor deposition of hydrogenated amorphous silicon

Michael J. McCaughey and Mark J. Kushner

Appl. Phys. Lett. 54, 1642 (1989); http://dx.doi.org/10.1063/1.101375 (3 pages) | Cited 10 times

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The rate of production of disilane (Si2H6) in silane (SiH4) plasmas by gas phase and surface‐catalyzed processes is examined. The discussion is based on results from plasma chemistry and surface deposition computer models. The surface model simulates the adsorption of silane radicals from the plasma on a growing amorphous silicon film and the subsequent desorption from the surface of the nonadhering SiH3 radicals as Si2H6. The rate of generation of Si2H6 from the surface reactions is compared to the rate of generation due to plasma reactions. We find that for conditions which are typical of those used for deposition of amorphous silicon, production of disilane is likely dominated by surface‐catalyzed processes. The rate of production, though, depends on the sticking coefficient of SiH3, which we find to be a function of plasma conditions.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
52.40.Hf Plasma-material interactions; boundary layer effects

New high‐rate sputtering‐type electron cyclotron resonance microwave plasma using an electric mirror

Morito Matsuoka and Ken’ichi Ono

Appl. Phys. Lett. 54, 1645 (1989); http://dx.doi.org/10.1063/1.101310 (3 pages) | Cited 8 times

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High‐rate sputtering is achieved by means of new electron cyclotron resonance microwave plasma employing sputtering using an electric mirror. This apparatus consists of both planar and cylindrical targets. Microwave power is perpendicularly or obliquely introduced into the resonance chamber. High‐density plasma of 1012 cm−3 is generated. The reflected electrons oscillating between the two targets play a major role in generating the dense plasma, i.e., as a beam‐plasma interaction. Both insulator and conductor films can be continuously deposited by this sputtering method at high rates under low gas pressures of 10−2 Pa. Al, Mo, and Fe films are deposited at rates above 2000 Å/min.
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81.15.Cd Deposition by sputtering
52.50.Dg Plasma sources

Measurements of the atomic nitrogen population produced by a microwave electron cyclotron resonance plasma

Scott Meikle and Yoshinori Hatanaka

Appl. Phys. Lett. 54, 1648 (1989); http://dx.doi.org/10.1063/1.101311 (2 pages) | Cited 18 times

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The atomic nitrogen population produced from a microwave electron cyclotron resonance plasma and a microwave plasma has been measured using the nitric oxide gas titration technique for pressures between 0.005 and 0.5 Torr. For 15 W microwave power the atomic nitrogen production efficiency is observed to reach a maximum of 12% at 0.006 Torr. The pressure dependence of atomic nitrogen production efficiency and concentration are found to fall by one order at the pressure where particle mean free path exceeds apparatus dimensions (0.015 Torr). The shift has been attributed to changing electron temperature.
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52.70.Nc Particle measurements
52.25.Fi Transport properties
34.80.Gs Molecular excitation and ionization
52.80.Pi High-frequency and RF discharges

Relation between the 1.9 eV luminescence and 4.8 eV absorption bands in high‐purity silica glass

Ryoichi Tohmon, Yasushi Shimogaichi, Shuji Munekuni, Yoshimichi Ohki, Yoshimasa Hama, and Kaya Nagasawa

Appl. Phys. Lett. 54, 1650 (1989); http://dx.doi.org/10.1063/1.101396 (3 pages) | Cited 34 times

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Photoluminescence measurements of the 1.9 eV emission were carried out on high‐purity silica glasses subjected to γ‐ray irradiation. The time decay of the luminescence, when excited by the 4.8 eV band, indicates that the 4.8 eV absorption and the 1.9 eV luminescence are caused by two different defects, and that an energy transfer occurs between the two defects. Comparison with electron spin resonance observations shows that both the nonbridging oxygen hole center (responsible for the 1.9 eV luminescence) and another undetermined defect (responsible for the 4.8 eV absorption) must be present in the glass before the 1.9 eV luminescence band can be excited by 4.8 eV photons.
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78.55.Hx Other solid inorganic materials
78.30.-j Infrared and Raman spectra
78.40.Fy Semiconductors

Nonlinear behavior of the field‐induced molecular tilt near the smectic A–C∗ transition

Sin‐Doo Lee and J. S. Patel

Appl. Phys. Lett. 54, 1653 (1989); http://dx.doi.org/10.1063/1.101296 (3 pages) | Cited 38 times

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A deviation from the linear relationship between induced molecular tilt and applied electric field has been observed in the vicinity of the transition from the smectic A to the chiral smectic C∗ phase. Near the transition temperature Tc, the induced tilt angle θ initially grows linearly with the strength of an applied electric field E, and clearly exhibits a crossover to Eα (1/3 <α<1) above a certain field strength. As temperature increases, however, the exponent α approaches 1 in a wide range of the electric field we studied. A simple mean field model is presented to explain the observed nonlinear behavior.
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61.30.Eb Experimental determinations of smectic, nematic, cholesteric, and other structures
61.30.Gd Orientational order of liquid crystals; electric and magnetic field effects on order
78.20.Jq Electro-optical effects

Formation of palladium silicide in the presence of Al with and without a carbon barrier layer

Chin‐An Chang

Appl. Phys. Lett. 54, 1656 (1989); http://dx.doi.org/10.1063/1.101411 (3 pages) | Cited 6 times

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The formation of Pd silicides in the presence of an Al layer is studied using Al/Pd/Si structures with and without a carbon barrier layer between the Al and Pd layers. Both the reactions between Al and Pd and between Pd and Si start around 200 °C, forming Pd2Al3 and Pd2Si, respectively. At higher temperatures, the excess Al present reacts with the Pd2Si formed, converting the latter to Pd2Al3 which is completed at 400 °C. In the presence of a carbon barrier layer using an Al/C/Pd/Si structure, the Pd2Si formed stays little changed up to an anneal of 30 min at 500 °C. The Pd2Si formed reacts with the Al present at higher temperatures, about two‐thirds reacted after an anneal at 550 °C, and nearly completely reacted after an anneal at 600 °C, both for 30 min. The effectiveness of the carbon barrier layer for the Al/Pd2Si reaction is compared with that for the Al/PtSi reaction, where little reaction is observed after an anneal of 30 min at 600 °C. Application of the carbon barrier layer to device contact metallurgies is also discussed.
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66.30.Ny Chemical interdiffusion; diffusion barriers
68.35.Fx Diffusion; interface formation
73.30.+y Surface double layers, Schottky barriers, and work functions
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy

Mechanism of formation of 〈110〉 oriented fivefold microcrystallites in diamond films

J. Narayan, A. R. Srivatsa, and K. V. Ravi

Appl. Phys. Lett. 54, 1659 (1989); http://dx.doi.org/10.1063/1.101297 (3 pages) | Cited 22 times

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We have investigated the formation of 〈110〉 oriented fivefold diamond microcrystallites on {001} silicon substrates using high‐resolution transmission electron microscopy (HRTEM). The HRTEM micrographs clearly show that fivefold symmetry in diamond microcrystallites results from twinning in {111} planes, in agreement with electron diffraction data. The five 〈110〉 oriented microcrystallites that provide fivefold symmetry are enclosed by {111} planes. The angles between various planes in these microcrystallites can be directly measured in HRTEM micrographs. The angles between {111} planes are found to vary from 70.5° (ideal) to as much as 74° for some microcrystallites. The boundaries of microcrystallites contain coherent twins with only occasional presence of dislocations to accommodate the misfit. We propose a model for nucleation and formation of fivefold diamond microcrystallites. The proposed model, based upon the presence of a/2〈110〉{001} edge dislocations, is found to be consistent with HRTEM observations.
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68.55.-a Thin film structure and morphology
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Threshold power density for photodecomposition of nitrocellulose

Yutang Ye and Robert G. Hunsperger

Appl. Phys. Lett. 54, 1662 (1989); http://dx.doi.org/10.1063/1.101298 (2 pages)

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The threshold power density for photodecomposition of nitrocellulose varies greatly with the irradiation mode and an interpretation of that fact is presented. The threshold conditions for different irradiation modes are described.
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82.50.Bc Processes caused by infrared radiation
82.50.Hp Processes caused by visible and UV light
79.20.Ds Laser-beam impact phenomena

Changes in composition and deposition rates in the reactive sputtering of copper, titanium, and yttrium exposed to oxygen

Takeshi Ohwaki and Yasunori Taga

Appl. Phys. Lett. 54, 1664 (1989); http://dx.doi.org/10.1063/1.101299 (2 pages) | Cited 10 times

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Copper, titanium, and yttrium oxide films were prepared by reactive dc magnetron sputtering in an Ar‐O2 plasma and the deposition rates and compositional changes were measured as a function of dc power. The deposition rates of Cu increased monotonically with increasing dc power, while those of Ti and Y increased abruptly by more than one order of magnitude at a critical dc power (Pc). Abrupt compositional changes of metal and oxygen in the thin films were also observed for Ti and Y at Pc. The compositional change curve for Cu had a plateau in dc power dependence. These results correlate with the differences of heat of oxide formation among Cu, Ti, and Y.
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81.15.Cd Deposition by sputtering
68.55.Nq Composition and phase identification
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy

Improvement of the photoelectric properties of amorphous SiCx:H by using disilylmethane as a feeding gas

W. Beyer, R. Hager, H. Schmidbaur, and G. Winterling

Appl. Phys. Lett. 54, 1666 (1989); http://dx.doi.org/10.1063/1.101412 (3 pages) | Cited 29 times

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Amorphous (a‐) SiCx:H films were deposited in a rf glow discharge of disilylmethane/silane mixtures. At optical gaps larger than 2 eV these films are found to have a higher photoconductivity than films prepared in conventional CH4/SiH4 gas mixtures. Both types of films are compared with respect to their hydrogen content as well as infrared and effusion spectra.
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73.50.Pz Photoconduction and photovoltaic effects
78.66.-w Optical properties of specific thin films
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Low‐loss Ti:LiNbO3 intersecting waveguides

Niraj Agrawal and L. McCaughan

Appl. Phys. Lett. 54, 1669 (1989); http://dx.doi.org/10.1063/1.101430 (3 pages) | Cited 2 times

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Interactions between guided and radiation modes are studied experimentally in Ti:LiNbO3 single‐mode, single‐Δn intersecting waveguides with small angles. These measurements, which cannot be interpreted in terms of any previous theory for intersecting waveguides, can be understood in terms of a recently developed multiple scattering analysis. Furthermore, it is found that the radiation losses in optical switches and crossovers can be dramatically reduced by a fractional doping of the intersection region.
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42.79.Gn Optical waveguides and couplers
42.79.Ta Optical computers, logic elements, interconnects, switches; neural networks

Novel self‐aligned W/TiN/TiSi2 contact structure for very shallow junctions and interconnections

R. V. Joshi, D. Moy, S. Brodsky, A. Charai, L. Krusin‐Elbaum, P. J. Restle, T. N. Nguyen, and C. S. Oh

Appl. Phys. Lett. 54, 1672 (1989); http://dx.doi.org/10.1063/1.101300 (3 pages) | Cited 11 times

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This letter describes a novel structure for very large scale integrated contact and interconnect technology that involves selective deposition of W on self‐aligned TiN/TiSi2. The TiN layer serves to protect reaction between WF6 and TiSi2 and underlying Si during W deposition as well as to promote adhesion of W layer and minimize contact resistance. The selective deposition of W on TiN, very difficult with conventional hydrogen reduction process, is accomplished by employing a recently developed silane reduction process. The structure prevents silicon consumption leading to the encroachment commonly found in tungsten deposited directly on silicon in very shallow junctions. It is demonstrated that such a structure results in low contact resistance and junction leakages and is applicable to subhalf‐micron devices. Tungsten with low resistivity of 8–9 μΩ cm can be achieved at room temperature with the resulting drop by a factor of 3–4 at liquid‐nitrogen temperature making the structure more attractive for low‐temperature application.
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85.40.Ls Metallization, contacts, interconnects; device isolation
73.40.Ns Metal-nonmetal contacts
73.40.Cg Contact resistance, contact potential

Photoluminescence studies of pseudomorphic modulation‐doped AlGaAs/InGaAs/GaAs quantum wells

A. Dodabalapur, V. P. Kesan, D. R. Hinson, D. P. Neikirk, and B. G. Streetman

Appl. Phys. Lett. 54, 1675 (1989); http://dx.doi.org/10.1063/1.101301 (3 pages) | Cited 29 times

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We discuss the photoluminescence (PL) properties of pseudomorphic modulation‐doped Al0.15Ga0.85As/In0.2Ga0.8As/GaAs quantum wells as a function of temperature. At 4.2 K, hole localization influences the PL linewidth; however, at higher temperatures (77 K) the thermal energy of photoexcited holes is sufficiently large to obtain a reliable measure of sheet carrier density from the PL linewidth. Our results also suggest that information about the interface quality can be obtained from an analysis of the PL linewidth at 77 and 4.2 K. The spectra taken from several samples clearly show that the PL transition energy exhibits a free‐carrier density dependence due to band‐gap renormalization and electric field effects.
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78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
78.55.Cr III-V semiconductors
73.61.Ey III-V semiconductors
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
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