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2 May 1994

Volume 64, Issue 18, pp. 2329-2458

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Cr4+:Gd3Sc2Ga3O12 passive Q‐switch for the Cr3+:LiCaAlF6 laser

Yen‐Kuang Kuo, Yang Yang, and Milton Birnbaum

Appl. Phys. Lett. 64, 2329 (1994); http://dx.doi.org/10.1063/1.111630 (3 pages) | Cited 4 times

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A Cr4+:Gd3Sc2Ga3O12 (Cr4+:GSGG) broad‐band saturable absorber has been demonstrated to be an excellent passive Q‐switch for the flashlamp‐pumped tunable Cr3+:LiCaAlF6 (Cr:LiCAF) laser at room temperature. A single Q‐switched laser output pulse of 11 mJ in energy and 37 ns in duration at 778 nm was obtained in a nonoptimized laser.
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42.55.Rz Doped-insulator lasers and other solid state lasers
42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
42.60.Fc Modulation, tuning, and mode locking

Noise suppression for photorefractive image amplification in the LiNbO3:Fe crystal sheet

Jingjun Xu, Guangyin Zhang, Simin Liu, Junmin Liu, and Liqiu Men

Appl. Phys. Lett. 64, 2332 (1994); http://dx.doi.org/10.1063/1.111631 (3 pages) | Cited 9 times

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The dependence of competition between the forward scattering light and climbing light in the LiNbO3:Fe crystal sheet on the incident angle of the pump light beam is discussed. On the basis of the light climbing and beam size effects, a new method for a low‐noise, high‐gain image amplification in thin crystal is described.
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42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
42.30.Wb Image reconstruction; tomography

Polarization‐independent wavelength filter using a grating‐assisted vertical directional coupler in InP

F. Heismann, L. L. Buhl, B. I. Miller, M. Newkirk, U. Koren, M. G. Young, and R. C. Alferness

Appl. Phys. Lett. 64, 2335 (1994); http://dx.doi.org/10.1063/1.111632 (3 pages) | Cited 10 times

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We demonstrate a polarization‐insensitive optical bandpass filter in indium phosphide (InP) with a 3 dB bandwidth of 1.5 nm at a center wavelength of 1.498 μm. The 5‐mm‐long filter is based on a grating‐assisted vertical directional coupler and features a novel double‐periodic coupling grating.
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42.79.Ci Filters, zone plates, and polarizers
42.79.Dj Gratings
42.82.Et Waveguides, couplers, and arrays

Optical near‐field imaging with a semiconductor probe tip

J. Mertz, M. Hipp, J. Mlynek, and O. Marti

Appl. Phys. Lett. 64, 2338 (1994); http://dx.doi.org/10.1063/1.111633 (3 pages) | Cited 16 times

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We present an optical near‐field detection mechanism based on optical modulation of the image force between a semiconducting probe tip and a glass surface. The modulation stems from a phenomenon called surface photovoltage. The performance of the mechanism for near‐field imaging is demonstrated by using a scanning force microscope over a standing evanescent light wave. The lateral resolution is found to be 170 nm (subwavelength) and a representative minimum detectable power is 0.1 pW/√Hz in air. We develop a simple theoretical model and discuss some possible applications.
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07.60.Pb Conventional optical microscopes
42.79.Pw Imaging detectors and sensors
72.40.+w Photoconduction and photovoltaic effects
73.30.+y Surface double layers, Schottky barriers, and work functions

Phase conjugation of BaTiO3:Ce by backward stimulated photorefractive scattering

Yong Zhu, Changxi Yang, Mengjun Hui, Xiaojuan Niu, Jinfeng Zhang, Tang Zhou, and Xing Wu

Appl. Phys. Lett. 64, 2341 (1994); http://dx.doi.org/10.1063/1.111608 (3 pages) | Cited 19 times

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We present a self‐pumped phase conjugator (SPPC) based on backward stimulated photorefractive scattering in a BaTiO3:Ce crystal in air without any external seed beam. Stable reflectivities of as much as 70% and good phase conjugate fidelity have been demonstrated in the 0°‐cut crystals. Over 50% reflectivities at 515 nm have been obtained at an incident angle between 20° and 70°. In comparison with undoped 0°‐cut and 45°‐cut crystals, the buildup time of SPPC is much faster for the same intensity.
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42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
42.30.Rx Phase retrieval
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates

Transmission electron microscopy characterization of InxGa1−xAs substrates grown by heteroepitaxial lateral overgrowth

J. P. McCaffrey, B. Bryskiewicz, T. Bryskiewicz, and E. Jiran

Appl. Phys. Lett. 64, 2344 (1994); http://dx.doi.org/10.1063/1.111609 (3 pages) | Cited 2 times

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InxGa1−xAs (x=0.04) ingots have been grown by liquid phase electroepitaxy (LPEE) on GaAs (001) substrates covered with a 0.2 μm thick SiO2 layer using a heteroepitaxial lateral overgrowth technique. Growth begins in 10 μm wide oxide‐free seeding windows oriented at approximately 30° to the {110} planes of the substrate, and proceeds laterally over adjacent 90 μm wide oxide strips. Transmission electron microscopy (TEM) analysis of the resulting material reveals a decrease in dislocation densities in the alloy layer, as dislocation nucleation occurs only at the seeding windows, while growth proceeds defect‐free over the oxide. Etching the seeding windows slightly into the substrate results in an increase in dislocation propagation into the substrate and under the oxide layer, and a lower dislocation density in the overlayer. The combination of the lateral overgrowth technique and the deeper window etching results in a significantly lower defect density in the InxGa1−xAs overlayer.
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68.37.Hk Scanning electron microscopy (SEM) (including EBIC)
68.37.Lp Transmission electron microscopy (TEM)
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
81.15.Lm Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids)

Anomalous laser‐induced voltages in YBa2Cu3Ox and ‘‘off‐diagonal’’ thermoelectricity

Louis R. Testardi

Appl. Phys. Lett. 64, 2347 (1994); http://dx.doi.org/10.1063/1.111610 (3 pages) | Cited 23 times

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Large anomalous laser‐induced voltages observed in YBa2Cu3Ox are explained as the result of ‘‘off diagonal’’ thermoelectricity, an uncommon phenomenon which may only occur in low symmetry environments. The effect is accompanied by a large electrical impedance transformation and the coupling of electrical and thermal currents in orthogonal directions. It thus offers new thin film applications for power generation, cooling, heat pumping, heat flow measurement, and the fast self‐powered sensing of optical and other radiation energy absorbed in thin layers.
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74.78.-w Superconducting films and low-dimensional structures
74.25.F- Transport properties
74.72.-h Cuprate superconductors

Raman scattering and x‐ray diffraction investigations of highly textured (Pb1−xLax)TiO3 thin films

Z. C. Feng, B. S. Kwak, A. Erbil, and L. A. Boatner

Appl. Phys. Lett. 64, 2350 (1994); http://dx.doi.org/10.1063/1.111611 (3 pages) | Cited 10 times

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Highly textured lead lanthanum titanate (PLT) thin films grown on Si(100) substrates by the metalorganic chemical vapor deposition technique are characterized using x‐ray diffraction (XRD), Raman spectroscopy, and energy‐dispersive x‐ray analysis. The texturing consisted of an alignment of the {100} crystallographic axes of the film perpendicular to the Si substrate. The tetragonality of the films was found to decrease as the lanthanum concentration increased. Raman spectra exhibited features characteristic of bulk PLT, including the observation of the soft mode. Variations of the phonon modes for PLT have been investigated as a function of La concentration and sample temperature.
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77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
78.30.Hv Other nonmetallic inorganics
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Thermal expansion of polycrystalline diamond produced by chemical vapor deposition

D. J. Pickrell, K. A. Kline, and R. E. Taylor

Appl. Phys. Lett. 64, 2353 (1994); http://dx.doi.org/10.1063/1.111612 (3 pages) | Cited 14 times

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The in‐plane thermal expansion of thick freestanding polycrystalline diamond films produced by hot filament chemical vapor deposition was measured by dilatometry. Measurements were obtained from two different diamond wafers over a temperature range of −200 to +800 °C. Within experimental error of the measurements, values agree with those reported for natural single‐crystal diamond. Quantification of the thermal expansion of chemically vapor deposited (CVD) diamond is important for determining thermal stresses which will be encountered during deposition of diamond on various substrate materials and during use of diamond in various applications.
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65.40.De Thermal expansion; thermomechanical effects
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Kinetic suppression of islanding in impurity‐mediated heteroepitaxial growth of germanium on silicon

H. J. Osten

Appl. Phys. Lett. 64, 2356 (1994); http://dx.doi.org/10.1063/1.111613 (3 pages) | Cited 7 times

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The impurity‐mediated suppression of islanding in molecular beam epitaxy growth experiments of Ge on Si(100) can be understood by a kinetic reduction of surface diffusion. Besides the energy barrier for surface diffusion, an energy barrier for a site exchange mechanism between Ge adatoms and the impurity atoms also has to be considered in a simple phenomenological approach that describes this effect. We found satisfactory agreement with different experimental results, like dependence of kinetic suppression of islanding on temperature and/or submonolayer coverage with impurities and germanium flux density.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.35.Rh Phase transitions and critical phenomena

Absence of solute drag in solidification

J. A. Kittl, M. J. Aziz, D. P. Brunco, and M. O. Thompson

Appl. Phys. Lett. 64, 2359 (1994); http://dx.doi.org/10.1063/1.111614 (3 pages) | Cited 24 times

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The interface response functions for alloy solidification were measured in the nondegenerate regime of partial solute trapping. We used a new technique to measure temperatures and velocities simultaneously during rapid solidification of Si‐As alloys induced by pulsed laser melting. In addition, partition coefficients were determined using Rutherford backscattering. The results are in good agreement with predictions of the Continuous Growth Model without solute drag of M. J. Aziz and T. Kaplan [Acta Metall. 36, 1335 (1988)] and are inconsistent with all solute drag models.
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81.10.Aj Theory and models of crystal growth; physics and chemistry of crystal growth, crystal morphology, and orientation
64.70.D- Solid-liquid transitions
81.30.Fb Solidification

Threshold voltage shift of amorphous silicon thin film transistors with atmospheric pressure chemical vapor deposition silicon dioxide

Jeong Hyun Kim, Eui Yeol Oh, Jung Kee Yoon, Yong Suk Park, and Chan Hee Hong

Appl. Phys. Lett. 64, 2362 (1994); http://dx.doi.org/10.1063/1.111615 (2 pages) | Cited 1 time

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The threshold voltage (Vth) shift of hydrogenated amorphous silicon thin film transistors (a‐Si:H TFTs) have been investigated for the atmospheric pressure chemical vapor deposition (APCVD) silicon dioxide (SiO2) gate insulator. For both positive and negative gate bias stress, the threshold voltage was shifted in the positive direction and was dominated by the defect creation near the a‐Si:H/SiO2 interface. There was little charge trapping into the APCVD SiO2 gate insulator under the gate bias stress. For the positive gate bias stress, the threshold voltage shifts of a‐Si:H TFTs with the a‐Si:H/SiO2 interface were smaller than those of the conventional a‐Si:H TFTs with the a‐Si:H/SiNx interface.
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85.30.Pq Bipolar transistors
73.61.Jc Amorphous semiconductors; glasses
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Blue electroluminescent devices with high quantum efficiency from alkoxy‐substituted poly(para‐phenylene vinylene)‐trimers in a polystyrene matrix

W. Tachelet, S. Jacobs, H. Ndayikengurukiye, H. J. Geise, and J. Grüner

Appl. Phys. Lett. 64, 2364 (1994); http://dx.doi.org/10.1063/1.111616 (3 pages) | Cited 35 times

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We report electroluminescence of electroluminescent devices fabricated from cis,trans‐ 2,5‐dimethoxy‐1,4 ‐bis[2‐(3,4,5‐trimethoxyphenyl)ethenyl]benzene blended in a polystyrene matrix as emission layer. This choice of materials avoids the inherently poor miscibility of polymers with other compounds and minimizes interactions between the host polymer and the electro‐optically active guest, which can produce quenching sites. A blue light‐emitting device with high internal quantum efficiency (∼1%) results.  
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78.60.Fi Electroluminescence
78.66.Qn Polymers; organic compounds
85.60.Jb Light-emitting devices
85.60.Pg Display systems

Optical properties of porous silicon superlattices

G. Vincent

Appl. Phys. Lett. 64, 2367 (1994); http://dx.doi.org/10.1063/1.111982 (3 pages) | Cited 88 times

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Porous silicon superlattices have been fabricated electrochemically. The current was monitored periodically during the electrolysis and samples were made with several periods. They have been investigated using reflectance measurements in the infrared and visible range. We demonstrate that porous silicon superlattices act like a multilayer dielectric device.
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78.30.Hv Other nonmetallic inorganics
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

Long‐wavelength stacked SiGe/Si heterojunction internal photoemission infrared detectors using multiple SiGe/Si layers

J. S. Park, T. L. Lin, E. W. Jones, H. M. Del Castillo, and S. D. Gunapala

Appl. Phys. Lett. 64, 2370 (1994); http://dx.doi.org/10.1063/1.111617 (3 pages) | Cited 13 times

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Utilizing low temperature silicon molecular beam epitaxy growth, long‐wavelength stacked SiGe/Si heterojunction internal photoemission (HIP) infrared detectors with multiple SiGe/Si layers have been fabricated and demonstrated. Using an elemental boron source, high doping concentration (≊4×1020 cm−3) has been achieved and high crystalline quality multiple Si0.7Ge0.3/Si layers have been obtained. The detector structure consists of several periods of degenerately boron doped (≊4×1020 cm−3) thin (≤50 Å) Si0.7Ge0.3 layers and undoped thick (≊300 Å) Si layers. The multiple p+‐Si 0.7Ge0.3/undoped‐Si layers show strong infrared absorption in the long‐wavelength regime mainly through free‐carrier absorption. The stacked Si0.7Ge0.3/Si HIP detectors with p=4×1020 cm−3 exhibit strong photoresponse at wavelengths ranging 2–20 μm with quantum efficiencies of about 4% and 1.5% at 10 and 15 μm wavelengths, respectively. The detectors show near ideal thermionic‐emission limited dark current characteristics.
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79.60.Jv Interfaces; heterostructures; nanostructures
78.66.Li Other semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Photoluminescence of Si/SiGe/Si quantum wells on separation by oxygen implantation substrate

D. K. Nayak, N. Usami, S. Fukatsu, and Y. Shiraki

Appl. Phys. Lett. 64, 2373 (1994); http://dx.doi.org/10.1063/1.111618 (3 pages) | Cited 3 times

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A study of the photoluminescence properties of Si/SiGe/Si quantum wells grown on separation by oxygen implantation (SIMOX) substrate by gas source molecular beam epitaxy is presented. Intense photoluminescence and carrier confinement in the quantum well are demonstrated. It is found that buried SiO2 isolates the top silicon on insulator from the back Si of SIMOX, and alters the photoluminescence properties of SIMOX compared to those of bulk Si. The SOI layer is found to be free of any strain. A SiO2/Si/SiO2 optical cavity is proposed by depositing SiO2 on SIMOX. A substantial enhancement of the photoluminescence intensity of SiGe quantum well is found, which is attributed to the optical confinement of incident beam in the cavity.
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78.55.Hx Other solid inorganic materials
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Photoluminescence of chemically vapor deposited Si on silica aerogels

Wanqing Cao and Arlon J. Hunt

Appl. Phys. Lett. 64, 2376 (1994); http://dx.doi.org/10.1063/1.111619 (3 pages) | Cited 14 times

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We have prepared in situ porous Si by the decomposition of SiH4 at 500 °C on an aerogel substrate. Electron microscopy studies indicate that the as‐deposited Si is primarily amorphous while the sample annealed in Ar at 800 °C has various nanometer‐sized crystalline Si particles. Visible photoluminescence (PL) can be observed only from the annealed sample and the PL peak red shifts with the annealing temperature from 800° to 1000 °C. The results support the quantum confinement theory as the luminescence mechanism in porous Si.
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78.55.Hx Other solid inorganic materials
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization
81.65.-b Surface treatments

Single electron transport and current quantization in a novel quantum dot structure

Y. Nagamune, H. Sakaki, L. P. Kouwenhoven, L. C. Mur, C. J. P. M. Harmans, J. Motohisa, and H. Noge

Appl. Phys. Lett. 64, 2379 (1994); http://dx.doi.org/10.1063/1.111620 (3 pages) | Cited 34 times

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We report on single electron transport via a novel quantum dot structure fabricated by a combination of mesa etching and gate formation. In this device electrons are confined in an etched submicron wire and squeezed further by two barrier gates. The resulting dot is of a very small size, and the number of confined electrons can be tuned down to the few electron limit. This novel structure has a large charging energy and an improved current quantization during turnstile operation. In small dots, containing only a few electrons, we found Coulomb oscillations with an unexplained multiple peak structure.
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73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
72.80.Ey III-V and II-VI semiconductors
85.30.De Semiconductor-device characterization, design, and modeling

Temperature dependence of cathodoluminescence from thin GaAs‐AlGaAs multiple quantum wells

U. Jahn, J. Menniger, R. Hey, and H. T. Grahn

Appl. Phys. Lett. 64, 2382 (1994); http://dx.doi.org/10.1063/1.111621 (3 pages) | Cited 10 times

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The temperature dependence of the cathodoluminescence (CL) intensity originating from GaAs‐Al0.3Ga0.7As multiple quantum wells has been measured between 5 and 300 K. The CL intensity drops exponentially by two orders of magnitude above 100 K with an activation energy of 83 meV between 140 and 200 K and 145 meV between 250 and 300 K. These energies are comparable to the effective barrier height of an electron or hole and an exciton, respectively. The decrease of the CL intensity is therefore attributed to thermal re‐emission of carriers and excitons out of the quantum well.
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73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
78.60.Hk Cathodoluminescence, ionoluminescence
78.66.Fd III-V semiconductors

Ultrafast carrier trapping and slow recombination in ion‐bombarded silicon on sapphire measured via THz spectroscopy

Stuart D. Brorson, Jucheng Zhang, and Søren R. Keiding

Appl. Phys. Lett. 64, 2385 (1994); http://dx.doi.org/10.1063/1.111622 (3 pages) | Cited 8 times

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We have performed two different types of femtosecond pump and probe measurements on THz transmitting antennas fabricated on ion‐bombarded silicon‐on‐sapphire chips. We find evidence that the decay of the photoexcited current occurs on a time scale of less than 1 ps. Simultaneously, we observe unambiguous evidence of screening originating from carriers trapped in long‐lived trap states. A simple model of carrier transport and screening in the presence of fast trapping and slow recombination is discussed.
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73.50.Pz Photoconduction and photovoltaic effects
84.40.Ba Antennas: theory, components and accessories
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
73.61.Cw Elemental semiconductors

Ultraviolet photosulfidation of III‐V compound semiconductors: A new approach to surface passivation

Carol I. H. Ashby, Kevin R. Zavadil, Arnold J. Howard, and B. E. (Gene) Hammons

Appl. Phys. Lett. 64, 2388 (1994); http://dx.doi.org/10.1063/1.111623 (3 pages) | Cited 6 times

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A new passivation technique for III‐V compound semiconductors based on ultraviolet photolysis of elemental sulfur vapor has been developed. Photosulfidation produces a greater increase in the photoluminescence intensity from GaAs samples than that produced by conventional (NH4)2S dip treatments and is more photostable than the conventional wet process. X‐ray photoelectron spectroscopy of the photosulfided GaAs surfaces indicate formation of a surface sulfide rather than the disulfide characteristic of the (NH4)2S process.
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81.65.-b Surface treatments
78.66.Fd III-V semiconductors
78.55.Cr III-V semiconductors
73.20.At Surface states, band structure, electron density of states

Laser‐induced sputtered neutral mass spectrometry study of arsenic concentration profiles in a polycrystalline silicon/single‐crystal silicon system

Yasuhiro Higashi, Tetsuya Maruo, Yoshikazu Homma, Jun’ichi Kodate, and Masayasu Miyake

Appl. Phys. Lett. 64, 2391 (1994); http://dx.doi.org/10.1063/1.111624 (3 pages) | Cited 1 time

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Arsenic concentration profiles in a polycrystalline silicon/single‐crystal silicon system were investigated by sputtered neutral mass spectrometry using a high‐repetition‐rate excimer laser. Beforehand, the arsenic profile in a SiO2/Si sample was measured to verify that this method can provide accurate profiles, unlike secondary ion mass spectrometry. The 300‐nm polycrystalline silicon film was implanted with 5×1016 As ions cm−2 at 100 keV and then annealed at 850 °C for 30 min. The arsenic segregation at the polycrystalline silicon/single‐crystal silicon interface was indisputably confirmed and the amount was accurately determined to be 2.2×1015 cm−2.
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07.75.+h Mass spectrometers
61.72.S- Impurities in crystals
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces

Electroluminescence from porous silicon with conducting polymer film contacts

Kun‐hsi Li, Dennis C. Diaz, Yuesong He, Joe C. Campbell, and Chaochieh Tsai

Appl. Phys. Lett. 64, 2394 (1994); http://dx.doi.org/10.1063/1.111625 (3 pages) | Cited 36 times

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Visible electroluminescence with a peak wavelength of 6300 Å is observed from forward‐biased porous Si p‐n diodes with conducting polymer contacts. These devices have brighter electroluminescence than similar devices with thin, gold‐film contacts. Electroluminescence is also observed from conducting polymer/n‐porous Si diodes.
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78.60.Fi Electroluminescence
78.66.Db Elemental semiconductors and insulators
78.66.Qn Polymers; organic compounds

Low‐temperature growth of high resistivity GaAs by photoassisted metalorganic chemical vapor deposition

J. C. Roberts, K. S. Boutros, S. M. Bedair, and D. C. Look

Appl. Phys. Lett. 64, 2397 (1994); http://dx.doi.org/10.1063/1.111626 (3 pages) | Cited 8 times

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We report the photoassisted low‐temperature (LT) metalorganic chemical vapor deposition (MOCVD) of high resistivity GaAs. The undoped as‐grown GaAs exhibits a resistivity of ∼106 Ω cm, which is the highest reported for undoped material grown in the MOCVD environment. Photoassisted growth of doped and undoped device quality GaAs has been achieved at a substrate temperature of 400 °C in a modified atmospheric pressure MOCVD reactor. By using silane as a dopant gas, the LT photoassisted doped films have high levels of doping and electron mobilities comparable to those achieved by MOCVD for growth temperatures, Tg≳600 °C.
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73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Evidence for population inversion in excited electron states of a double barrier resonant tunneling structure

J. W. Cockburn, M. S. Skolnick, D. M. Whittaker, P. D. Buckle, A. R. K. Willcox, and G. W. Smith

Appl. Phys. Lett. 64, 2400 (1994); http://dx.doi.org/10.1063/1.111627 (3 pages) | Cited 9 times

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We report evidence for a population inversion between excited electron states of the quantum well of a GaAs‐AlGaAs double barrier resonant tunneling structure (DBRTS). The relative populations of the states are determined by photoluminescence spectroscopy of the tunneling electrons in the structure. When the DBRTS is biased at the fourth electron resonance, the population of the n=4 confined level is found to be greater than that of the n=3 state. We show that such a population inversion is consistent with a rate equation analysis of the relative populations of the two levels when electrons tunnel into n=4.
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73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
78.45.+h Stimulated emission
73.40.Gk Tunneling
78.55.Cr III-V semiconductors
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