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2 Nov 1998

Volume 73, Issue 18, pp. 2543-2690

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Direct micropatterning of Si and GaAs using electrochemical development of focused ion beam implants

P. Schmuki and L. E. Erickson

Appl. Phys. Lett. 73, 2600 (1998); http://dx.doi.org/10.1063/1.122518 (3 pages) | Cited 4 times

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Focused ion beam implantation of Si++ was used to write defined surface damage/implant patterns into n-type GaAs (100) and Si (100) substrates. These implant sites represent initiation sites for dissolution processes when electrochemically polarized in HCl or HF electrolytes, respectively. Selective dissolution within the patterns is achieved if anodic polarization of the n-type material is carried out in the dark at potentials below (cathodic to) the onset of dissolution potential of the unimplanted surface. Uniform etching within the implanted region takes place, when local electropolishing conditions are established. Thus, highly defined etch patterns, e.g., lines, gratings, or pits, can be produced in the submicron range. The depth of the etched patterns corresponds to the implant/damage profile created in the implantation process and etch stop occurs at less reactive crystal planes. © 1998 American Institute of Physics.
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81.05.Cy Elemental semiconductors
81.05.Ea III-V semiconductors
81.65.Cf Surface cleaning, etching, patterning
85.40.Ry Impurity doping, diffusion and ion implantation technology
81.65.Ps Polishing, grinding, surface finishing
61.72.uf Ge and Si
61.72.uj III-V and II-VI semiconductors

Initial carrier relaxation dynamics in ion-implanted Si nanocrystals: Femtosecond transient absorption study

V. I. Klimov, Ch. J. Schwarz, D. W. McBranch, and C. W. White

Appl. Phys. Lett. 73, 2603 (1998); http://dx.doi.org/10.1063/1.122519 (3 pages) | Cited 31 times

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Transient absorption spectra of ion-implanted Si nanocrystals (NCs) exhibit two picosecond photoinduced absorption features, attributed to carriers in NC quantized states (high-energy band) and Si/SiO2 interface states (low-energy band). Fast relaxation of the high-energy band indicates that populations of quantized states are short lived and decay on the sub-10-ps time scale due to efficient surface trapping. This shows that the red emission in our samples is not due to carriers in quantized states but rather is a result of deactivation of surface traps. © 1998 American Institute of Physics.
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61.72.uf Ge and Si
78.47.-p Spectroscopy of solid state dynamics
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
78.40.Fy Semiconductors
72.80.Cw Elemental semiconductors
61.46.-w Structure of nanoscale materials

Raman and x-ray studies of InN films grown by metalorganic vapor phase epitaxy

Ming-Chih Lee, Heng-Ching Lin, Yung-Chung Pan, Chen-Ke Shu, Jehn Ou, Wen-Hsiung Chen, and Wei-Kuo Chen

Appl. Phys. Lett. 73, 2606 (1998); http://dx.doi.org/10.1063/1.122520 (3 pages) | Cited 32 times

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Thin InN films were deposited on the (0001) sapphire substrate at various temperatures from 325 to 600 °C by metalorganic vapor phase epitaxy. We used Raman scattering and x-ray diffraction to investigate the film properties and crystalline structures. Significant line broadening, softening and intensity evolution were observed at the growth temperatures between 375 and 450 °C. This can be attributed to the formation of the mixed hexagonal and cubic structures and the related dislocation defects. As the growth temperature is further increased, the hexagonal phase is found to be dominant in the deposited InN film. © 1998 American Institute of Physics.
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81.15.Kk Vapor phase epitaxy; growth from vapor phase
78.66.Fd III-V semiconductors
78.30.Fs III-V and II-VI semiconductors
81.05.Ea III-V semiconductors
68.55.-a Thin film structure and morphology

Significance of tunneling in p+ amorphous silicon carbide n crystalline silicon heterojunction solar cells

M. W. M. van Cleef, R. E. I. Schropp, and F. A. Rubinelli

Appl. Phys. Lett. 73, 2609 (1998); http://dx.doi.org/10.1063/1.122521 (3 pages) | Cited 13 times

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We used the internal photoemission (IPE) technique to accurately determine the valence and conduction band offsets at the a-SiC:H/c-Si interface and investigated with numerical simulations their effects on the photocarrier collection in p+ a-SiC:H/n c-Si heterojunction solar cells. The valence and conduction band discontinuities were found to be 0.60 and 0.55 eV, respectively. However, despite the large barrier at the valence band edge, 30 nm p+ a-SiC:H/n c-Si heterojunction solar cells show no collection problems due to blocking of holes (FF = 0.73). Combined IPE measurements and simulation results indicate that tunneling of holes through this barrier at the valence band edge can explain the unhindered collection. © 1998 American Institute of Physics.
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84.60.Jt Photoelectric conversion
73.20.At Surface states, band structure, electron density of states
73.40.Gk Tunneling
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.61.Jc Amorphous semiconductors; glasses
73.61.Cw Elemental semiconductors

Field-dependent absorption in superlattices: Comparison of theory and experiment

A. Thränhardt, H. J. Kolbe, J. Hader, T. Meier, G. Weiser, and S. W. Koch

Appl. Phys. Lett. 73, 2612 (1998); http://dx.doi.org/10.1063/1.122522 (3 pages) | Cited 6 times

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Absorption and differential electroabsorption spectra of a GaInAs/InP superlattice in the regime of Wannier–Stark localization are compared with spectra derived from the Semiconductors Bloch Equations. The absorption is strongly underestimated for higher energies by the effective mass approximation but good agreement is achieved by using an energy dependent in-plane effective mass. No fitting parameters are used except for a phenomenological broadening. The lineshape of the field-modulated spectra is dominated by the strong field dependence of Wannier–Stark transitions and depends on the amplitude of the modulating field which should be kept small for best results. © 1998 American Institute of Physics.
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78.66.Fd III-V semiconductors
78.20.Jq Electro-optical effects
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems

Formation of self-assembled GaAs/AlGaAs quantum dots by low-temperature epitaxy

Chae-Deok Lee, Chanro Park, Hwack Joo Lee, S. K. Noh, Kyu-Seok Lee, and Seong-Ju Park

Appl. Phys. Lett. 73, 2615 (1998); http://dx.doi.org/10.1063/1.122523 (3 pages) | Cited 8 times

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We report the direct formation of self-assembled GaAs/AlGaAs quantum dots by low-temperature molecular beam epitaxy. To drive a three dimensional growth mode, the (1×1) AlGaAs surface was exposed alternately to the Ga and As sources. The resulting GaAs nanocrystals having {111} facets were clearly identified by high-resolution transmission electron microscopy. The emission spectra also confirmed the formation of dots. The transition to a three-dimensional growth mode is attributed to the limited surface migration of Ga adatoms on the AlGaAs surface, which has excess As at low substrate temperature. © 1998 American Institute of Physics.
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81.05.Ea III-V semiconductors
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
73.61.Ey III-V semiconductors

Electrical detection of optically induced charge storage in self-assembled InAs quantum dots

J. J. Finley, M. Skalitz, M. Arzberger, A. Zrenner, G. Böhm, and G. Abstreiter

Appl. Phys. Lett. 73, 2618 (1998); http://dx.doi.org/10.1063/1.122524 (3 pages) | Cited 108 times

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Spectrally resolved photoresistance investigations of charge storage effects in self-assembled InAs quantum dots (QDs) are reported. Resonant optical excitation of the QDs produces a strong increase of the lateral resistance of a spatially separated electron channel (ΔR) which reflects the stored charge density. This photoresponse is persistent for many hours at 145 K and can be controllably reversed electrically. Pronounced oscillations observed in the spectral variation ΔR are shown to reflect the excitation spectrum of the QD ensemble showing resonances that arise from both direct and phonon-assisted absorption processes. © 1998 American Institute of Physics.
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72.80.Ey III-V and II-VI semiconductors
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
73.61.Ey III-V semiconductors
73.50.Pz Photoconduction and photovoltaic effects

Quantum tailoring of optical transitions in InxGa1−xAs/AlAs strained quantum wells

Jean Marc Jancu, Vittorio Pellegrini, Raffaele Colombelli, Fabio Beltram, Bernhard Mueller, Lucia Sorba, and Alfonso Franciosi

Appl. Phys. Lett. 73, 2621 (1998); http://dx.doi.org/10.1063/1.122525 (3 pages) | Cited 13 times

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The optical properties of n-doped InxGa1−xAs/AlAs pseudomorphic quantum wells grown on GaAs(001) are investigated as a function of layer thickness and indium concentration. The nature of interband and intersubband transitions is clarified using an improved tight-binding model and a combination of low-temperature photoluminescence spectroscopy and intersubband absorption studies. A type I→type II crossover is found to occur in very narrow wells. Moreover, for appropriate quantum-well parameters, tailoring of the intersubband transition wavelength down to the 1.2 μm range appears feasible while retaining the type I character of the band alignment. These results provide a valid framework for the implementation of InxGa1−xAs/AlAs heterostructures for ultrafast optical communication applications. © 1998 American Institute of Physics.
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78.66.Fd III-V semiconductors
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
78.55.Cr III-V semiconductors
78.30.Fs III-V and II-VI semiconductors
71.15.Ap Basis sets (LCAO, plane-wave, APW, etc.) and related methodology (scattering methods, ASA, linearized methods, etc.)

Low-temperature-grown GaAs enhanced wet thermal oxidation of Al0.98Ga0.02As

H. Reese, Y. J. Chiu, and E. Hu

Appl. Phys. Lett. 73, 2624 (1998); http://dx.doi.org/10.1063/1.122526 (3 pages) | Cited 9 times

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The effects of incorporating low-temperature-grown GaAs (LT GaAs) into the layer structure of Al0.98Ga0.02As/GaAs are studied. Results show that the structures containing a 300 nm layer of LT GaAs have faster oxidation rates and lower oxidation temperatures compared to reference samples without the LT GaAs layer. This letter will discuss the mechanisms involved in the oxidation rate increase, attributed to the LT GaAs enhancing the transport of As species during the oxidation process. © 1998 American Institute of Physics.
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81.05.Ea III-V semiconductors
81.65.Mq Oxidation
68.60.Dv Thermal stability; thermal effects
78.66.Fd III-V semiconductors
78.55.Cr III-V semiconductors
68.55.-a Thin film structure and morphology

Field-activated structural traps at organic pigment/metal interfaces causing photocurrent multiplication phenomena

Masahiro Hiramoto, Ken-ichi Nakayama, Tadashi Katsume, and Masaaki Yokoyama

Appl. Phys. Lett. 73, 2627 (1998); http://dx.doi.org/10.1063/1.122507 (3 pages) | Cited 6 times

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Carrier traps at the perylene pigment/metal interface, which give rise to a large photocurrent multiplication phenomenon showing a gain of more than 104-fold, were investigated. The energetic depth of these traps increased with applied electric field, contrary to the behavior of usual electronic traps. To explain this, a model of field-activated structural traps was proposed; that is, dead ends at an imperfect organic/metal contact capture holes more tightly under a stronger electric field. Estimated values of five trapped holes per 10 nm2 and dead ends of the order of 1 nm long suggest that the proposed structural traps are closely related to the molecular-sized roughness at the pigment surface. © 1998 American Institute of Physics.
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73.40.Ns Metal-nonmetal contacts
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
72.40.+w Photoconduction and photovoltaic effects

Optical properties of GaN-rich side of GaNP and GaNAs alloys grown by gas-source molecular beam epitaxy

R. Kuroiwa, H. Asahi, K. Asami, S.-J. Kim, K. Iwata, and S. Gonda

Appl. Phys. Lett. 73, 2630 (1998); http://dx.doi.org/10.1063/1.122535 (3 pages) | Cited 23 times

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GaN-rich side of GaNP and GaNAs layers is grown at 750 °C by gas-source molecular beam epitaxy. Phase separation is observed for the layers with P and As composition of over 1.5% and 1%, respectively. Photoluminescence (PL) spectra for the non-phase-separated GaNP (P composition: 0.37%) and GaNAs (As composition: 0.26%) show redshift of 50 and 40 meV, respectively, from that of GaN, and exhibit Stokes shift of about 80 meV which is smaller than that of GaN (100 meV). On the other hand, the PL spectrum for the phase-separated GaNP shows a large redshift peaking at 2.101 eV. This peak is considered to be an emission from the phase-separated GaP-rich GaPN region. PL excitation spectrum shows two large broad peaks. One at 2.982 eV corresponds to the absorption at the Γ point of GaP-rich region, and the other at 2.308 eV corresponds to the absorption at the isoelectronic band edge of GaP-rich GaPN alloy originated from the X point of GaP. In the case of phase-separated GaNAs, no PL is observed, suggesting that the optical properties are much more sensitive to crystalline quality in GaAs-rich GaAsN than in GaP-rich GaPN. © 1998 American Institute of Physics.
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78.66.Fd III-V semiconductors
78.55.Cr III-V semiconductors
81.05.Ea III-V semiconductors
68.55.Nq Composition and phase identification
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
71.20.Nr Semiconductor compounds

Precipitation of As in thermally oxidized ion-implanted Si crystals

A. Terrasi, E. Rimini, V. Raineri, F. Iacona, F. La Via, S. Colonna, and S. Mobilio

Appl. Phys. Lett. 73, 2633 (1998); http://dx.doi.org/10.1063/1.122536 (3 pages) | Cited 5 times

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The As precipitation occurring during thermal oxidation of As implanted Si crystals has been studied by extended x-ray absorption fine structure measurements. (100) Si wafers, implanted with 3×1015/cm2 and 3×1016/cm2 As+ ions at an energy of 70 keV, were oxidized either in H2O ambient (wet) at 920 °C or O2 (dry) at 1100 °C. Precipitation of monoclinic SiAs occurs at the SiO2/Si interface for low temperature oxidation processes. In the case of 3×1016 As/cm2, about 90% of the As forms SiAs precipitates, while for the lower dose a mixing of precipitates and As in substitutional-like sites is observed. On the other hand, when the high temperature oxidation is performed, most of the As (up to 90% for the 3×1015 As/cm2 sample) is found in a substitutional-like configuration. © 1998 American Institute of Physics.
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61.72.uf Ge and Si
81.05.Cy Elemental semiconductors
85.40.Ry Impurity doping, diffusion and ion implantation technology
68.35.Ct Interface structure and roughness
81.65.Mq Oxidation
78.70.Dm X-ray absorption spectra
64.75.-g Phase equilibria
81.30.Mh Solid-phase precipitation

Photoluminescence excitation spectroscopy of free-to-bound transitions in undoped GaN grown by hydride vapor phase epitaxy

S. J. Rhee, S. Kim, E. E. Reuter, S. G. Bishop, and R. J. Molnar

Appl. Phys. Lett. 73, 2636 (1998); http://dx.doi.org/10.1063/1.122537 (3 pages) | Cited 15 times

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Temperature-dependent photoluminescence excitation (PLE) spectroscopy has been carried out on the yellow band (YB) in GaN. The 5 K PLE spectra demonstrate that the exciting light must have photon energy large enough to generate free carriers or carriers localized on shallow impurities in order to excite the YB effectively. With increasing temperatures, progressively deeper energy levels can be thermally ionized, enabling extrinsic absorption by these deeper levels to generate the free holes required to excite the YB emission. The broad below-band gap PLE response then exhibits thermally activated onsets attributed to these free-to-bound transitions. One such onset corresponds to the well-known 205 meV acceptor, and a second onset provides conclusive evidence for the existence of a previously unconfirmed ∼ 120 meV impurity or defect level in GaN. © 1998 American Institute of Physics.
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72.80.Ey III-V and II-VI semiconductors
81.15.Kk Vapor phase epitaxy; growth from vapor phase
78.66.Fd III-V semiconductors
78.55.Cr III-V semiconductors

Efficient gettering of low concentrations of copper contamination to hydrogen induced nanocavities in silicon

A. Kinomura, J. S. Williams, J. Wong-Leung, M. Petravic, Y. Nakano, and Y. Hayashi

Appl. Phys. Lett. 73, 2639 (1998); http://dx.doi.org/10.1063/1.122538 (3 pages) | Cited 10 times

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The efficient gettering to hydrogen-induced cavities in Si has been successfully demonstrated for low concentrations of Cu, unintentionally introduced during wafer processing. Secondary ion mass spectrometry showed up to 5×1012 cm−2Cu could be introduced into a silicon wafer and trapped at cavities. Neutron activation analysis indicated that, in samples with cavities, the Cu within the bulk was below the detection limit (around 4×1011 cm−2), while Cu was detected throughout the bulk of samples without cavities. © 1998 American Institute of Physics.
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61.72.Yx Interaction between different crystal defects; gettering effect
81.65.Tx Gettering
81.05.Cy Elemental semiconductors
81.07.-b Nanoscale materials and structures: fabrication and characterization
61.72.Qq Microscopic defects (voids, inclusions, etc.)

Improved quality GaN grown by molecular beam epitaxy using In as a surfactant

F. Widmann, B. Daudin, G. Feuillet, N. Pelekanos, and J. L. Rouvière

Appl. Phys. Lett. 73, 2642 (1998); http://dx.doi.org/10.1063/1.122539 (3 pages) | Cited 76 times

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The surfactant effect of In during the growth of GaN by molecular beam epitaxy has been investigated. It has been found that the presence of In modifies the diffusion kinetics in the growing GaN surface, leading to the observation of persistent reflection high energy electron diffraction intensity oscillations, characteristic of layer-by-layer growth. Electron microscopy studies revealed drastic modifications of the GaN structural properties associated with the presence of In during the growth. When grown in the presence of In, GaN exhibits an intense band edge luminescence, free of the component at 3.41 eV which is characteristic of defects associated with growth in N-rich conditions. © 1998 American Institute of Physics.
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68.55.-a Thin film structure and morphology
81.05.Ea III-V semiconductors
68.35.Fx Diffusion; interface formation
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors

Conduction properties of metal/organic monolayer/semiconductor heterostructures

DeQuan Li, A. Bishop, Y. Gim, X. B. Shi, M. R. Fitzsimmons, and Q. X. Jia

Appl. Phys. Lett. 73, 2645 (1998); http://dx.doi.org/10.1063/1.122540 (3 pages) | Cited 8 times

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We have fabricated and characterized rectifying devices made of metal/organic monolayer/semiconductor heterostructures. The devices consist of an organic barrier layer sandwiched between an aluminum (Al) metal contact and a p-type Si semiconductor. The barrier materials were chosen from three types of self-assembled monolayers (SAMs) with different electronic properties: (1) wide-band gap poly(diallydimethyl ammonium) chloride (PDDA), (2) narrow-band gap PDDA/NiPc (nickel phthalocyanine tetrasulfonate), and (3) donor type PDDA/PPP (poly p-quaterphenylene-disulfonic-dicarboxylic acid). From current–voltage (I–V) measurements at room temperature, we have found the turn-on voltage of the devices can be tuned by varying the structure, hence electronic properties, of the organic monolayers, and that there exists a power-law dependence of I on V, I∝Vα, with the exponent α = 2.2 for PDDA, 2.7 for PDDA/NiPc, and 1.44 for PDDA/PPP as the barrier layer, respectively. Our results imply that the transport properties are controlled by both the electronic properties of the SAMs and those of the metal and semiconductor, as indicated by the power-law dependence of the I–V characteristics. © 1998 American Institute of Physics.
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73.40.Ei Rectification
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)

Phonon signatures of spontaneous CuPt ordering in Ga0.47In0.53As/InP

Hyeonsik M. Cheong, S. Phillip Ahrenkiel, Mark C. Hanna, and Angelo Mascarenhas

Appl. Phys. Lett. 73, 2648 (1998); http://dx.doi.org/10.1063/1.122541 (3 pages) | Cited 5 times

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Polarized Raman scattering spectra of spontaneously ordered Ga0.47In0.53As alloys, combined with low-temperature photoluminescence and transmission electron microscopy, are used to find a unique phonon signature of CuPtB-type ordering. In the Raman spectra of ordered alloys, a new phonon peak that is absent in the spectrum of the random alloy appears at 181 cm−1. The intensity of this peak correlates with the degree of ordering inferred from electron diffraction measurements. We propose that Raman scattering measurements can be used as a nondestructive probe to detect spontaneous ordering in this alloy. © 1998 American Institute of Physics.
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78.66.Fd III-V semiconductors
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
78.55.Cr III-V semiconductors
78.30.Fs III-V and II-VI semiconductors

Spatial ordering of islands grown on patterned surfaces

Choongseop Lee and Albert-László Barabási

Appl. Phys. Lett. 73, 2651 (1998); http://dx.doi.org/10.1063/1.122542 (3 pages) | Cited 26 times

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We demonstrate that growth on a sample patterned with an ordered defect array can lead to islands with rather narrow size distribution. However, improvement in the size distribution is achieved only if the growth conditions (flux and temperature) have optimal values, determined by the patterning length scale. Since the scanning tunelling and the atomic force microscopes are capable of inducing surface perturbations that act as potential preferential nucleation sites, our work demonstrates that nanoscale surface patterning can improve the ordering of platelets and self-assembled quantum dots. © 1998 American Institute of Physics.
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68.55.-a Thin film structure and morphology
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
68.35.B- Structure of clean surfaces (and surface reconstruction)
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
61.82.Rx Nanocrystalline materials
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Crystallographic wet chemical etching of GaN

D. A. Stocker, E. F. Schubert, and J. M. Redwing

Appl. Phys. Lett. 73, 2654 (1998); http://dx.doi.org/10.1063/1.122543 (3 pages) | Cited 68 times

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We demonstrate well-controlled crystallographic etching of wurtzite GaN grown on c-plane sapphire using H3PO4, molten KOH, KOH dissolved in ethylene glycol, and NaOH dissolved in ethylene glycol between 90 and 180 °C, with etch rates as high as 3.2 μm/min. The crystallographic GaN etch planes are {0001}, {10math0}, {10math math}, {10math math}, and {10math3}. The vertical {10math0} planes appear perfectly smooth when viewed with a field-effect scanning electron microscope. The activation energy is 21 kcal/mol, indicative of reaction-rate limited etching. © 1998 American Institute of Physics.
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81.65.Cf Surface cleaning, etching, patterning
81.05.Ea III-V semiconductors

Photovoltage and photoreflectance spectroscopy of InAs/GaAs self-organized quantum dots

B. Q. Sun, Z. D. Lu, D. S. Jiang, J. Q. Wu, Z. Y. Xu, Y. Q. Wang, J. N. Wang, and W. K. Ge

Appl. Phys. Lett. 73, 2657 (1998); http://dx.doi.org/10.1063/1.122544 (3 pages) | Cited 38 times

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We present a detailed study of the interband excitonic transitions of InAs/GaAs self-organized quantum dots (QDs) based on photovoltage (PV), photoreflectance (PR) and photoluminescence (PL) spectroscopy. At room temperature, the interband absorption transitions of QDs have been observed by using PV spectrum, which clearly exhibits four well-resolved excitonic absorption peaks. The absorption line shape is Gaussian-like. Furthermore, the corresponding excitonic transitions are also observed in PR experiment at 77 K. The first derivative of a Gaussian profile can fit the experimental data well. © 1998 American Institute of Physics.
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78.66.Fd III-V semiconductors
71.35.Cc Intrinsic properties of excitons; optical absorption spectra
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
73.61.Ey III-V semiconductors
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
78.55.Cr III-V semiconductors
73.50.Pz Photoconduction and photovoltaic effects
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