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13 Dec 1999

Volume 75, Issue 24, pp. 3739-3886

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Single step process for epitaxial lateral overgrowth of GaN on SiC and sapphire substrates

J. A. Smart, E. M. Chumbes, A. T. Schremer, and J. R. Shealy

Appl. Phys. Lett. 75, 3820 (1999); http://dx.doi.org/10.1063/1.125467 (3 pages) | Cited 11 times

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Using flow modulation organometallic vapor phase epitaxy, a process has been developed which produces epitaxial lateral overgrowth of GaN-base materials directly on SiC and sapphire substrates patterned with silicon nitride. The key feature of this single step process is the use of a high temperature AlGaN nucleation layer which wets the exposed substrate surface, without significant nucleation on the mask. This eliminates the need for regrowth while producing smooth growth surfaces in the window opening as well as over the mask. Subsequent GaN deposition results in relatively defect free materials grown laterally over the mask. Using arrays of stripe windows aligned parallel to the 〈1math00〉 crystal direction, the epitaxial films completely planarize after roughly 5 microns of growth. Defect densities estimated from atomic force micrographs indicate a reduction from mid 108 to 105 cm−2 in regions over the window and over the mask, respectively. This process represents a significant simplification over currently used regrowth methods for obtaining low defect density laterally overgrown GaN materials. © 1999 American Institute of Physics.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.15.Kk Vapor phase epitaxy; growth from vapor phase
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
68.35.B- Structure of clean surfaces (and surface reconstruction)
61.72.-y Defects and impurities in crystals; microstructure

Photovoltaic effect of cubic GaN/GaAs(100)

D. G. Zhao, D. S. Jiang, Hui Yang, L. X. Zheng, D. P. Xu, J. B. Li, and Q. M. Wang

Appl. Phys. Lett. 75, 3823 (1999); http://dx.doi.org/10.1063/1.125468 (3 pages) | Cited 3 times

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We have studied the photovoltaic effect in cubic GaN on GaAs at room temperature. The photovoltaic spectra of cubic GaN epitaxial film were concealed by the photovoltaic effect from the GaAs substrate unless additional illumination of a 632.8 nm He–Ne laser beam was used to remove the interference of the GaAs absorption in the measurement. On the basis of the near-band-edge photovoltaic spectra of cubic GaN, we obtained the minority carrier diffusion lengths of about 0.32 and 0.14 μm for two undoped n-type cubic GaN samples with background concentrations of 1014 and 1018 cm−3, respectively. © 1999 American Institute of Physics.
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73.61.Ey III-V semiconductors
73.50.Pz Photoconduction and photovoltaic effects
72.40.+w Photoconduction and photovoltaic effects
72.80.Ey III-V and II-VI semiconductors
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths

High-quality GaAs on Si substrate by the epitaxial lift-off technique using SeS2

J. Arokiaraj, T. Soga, T. Jimbo, and M. Umeno

Appl. Phys. Lett. 75, 3826 (1999); http://dx.doi.org/10.1063/1.125469 (3 pages) | Cited 9 times

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In this letter, we demonstrate the realization of strong bonding between GaAs epilayers on Si substrates by using selenium sulphide (SeS2) compound. After bonding, the sample has been transplanted to Si substrate using the epitaxial lift-off process. Such a transplanted film was found to be very smooth and adhered well to Si. The resulting chemical bond was covalent in nature, robust, and withstood clean room processing steps. The film bonded in this manner exhibited very good photoluminescence and high crystal quality by double crystal x-ray diffraction. The double crystal x-ray diffraction had a low full width at half maximum of 44 arcsec, and the strain was absent in these types of heterostructures. The interfacial chemical reaction and bonding were studied by depth profile x-ray photoelectron spectroscopy. It was concluded that Ga–Se and Si–S phases such as Ga2Se3 and SiS2 were responsible for the strong bonding between GaAs and Si. © 1999 American Institute of Physics.
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68.35.Ct Interface structure and roughness
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.65.Cf Surface cleaning, etching, patterning
68.35.Gy Mechanical properties; surface strains
81.05.Ea III-V semiconductors
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
68.55.-a Thin film structure and morphology
68.35.Fx Diffusion; interface formation

Imaging near-contact transport in the planar-collector geometry for a Schottky contact on high-purity GaAs

K. A. Record, D. R. Palmieri, N. M. Haegel, and D. Wynne

Appl. Phys. Lett. 75, 3829 (1999); http://dx.doi.org/10.1063/1.125470 (3 pages) | Cited 4 times

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Variable temperature electron beam induced current (EBIC) and cathodoluminescence (CL) were combined to image electric fields and charge transport for a Schottky contact on high purity epitaxial GaAs in the planar-collector geometry. Simultaneous EBIC and CL imaging proves that the near-contact EBIC signal is dominated by depletion effects, even in material where the bulk diffusion length greatly exceeds the intercontact distance. In forward bias, an EBIC dipole is observed, providing direct spatial indication of the transition between drift and diffusion transport of locally generated charge. © 1999 American Institute of Physics.
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73.30.+y Surface double layers, Schottky barriers, and work functions
81.05.Ea III-V semiconductors
72.80.Ey III-V and II-VI semiconductors
78.60.Hk Cathodoluminescence, ionoluminescence
68.37.Hk Scanning electron microscopy (SEM) (including EBIC)
68.37.Lp Transmission electron microscopy (TEM)
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
72.60.+g Mixed conductivity and conductivity transitions

Energy relaxation by photoexcited carriers in the InAs/GaAs quantum-dot system: Bolometric detection of strong acoustic-phonon emission

P. Hawker, A. J. Kent, and M. Henini

Appl. Phys. Lett. 75, 3832 (1999); http://dx.doi.org/10.1063/1.125471 (3 pages) | Cited 12 times

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We have used bolometric detection to observe directly the phonons emitted by photoexcited carriers in the InAs/GaAs self-organized quantum-dot system. We find that about 74% of the energy lost by carriers in the InAs dots and wetting layer is via emission of low-frequency acoustic phonons and argue that this is facilitated by Auger scattering. © 1999 American Institute of Physics.
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63.22.-m Phonons or vibrational states in low-dimensional structures and nanoscale materials
63.20.K- Phonon interactions
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
73.61.Ey III-V semiconductors

Localized states at InGaN/GaN quantum well interfaces

L. J. Brillson, T. M. Levin, G. H. Jessen, and F. A. Ponce

Appl. Phys. Lett. 75, 3835 (1999); http://dx.doi.org/10.1063/1.125472 (3 pages) | Cited 22 times

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Low-energy electron-excited nanoscale-luminescence (LEEN) spectroscopy of GaN/InGaN/GaN double-heterojunction structures reveal the formation of electronic states localized near the quantum well interfaces under relatively In-rich conditions. These states are due to formation in a cubic GaN region comparable to the quantum well layer in thickness rather than the bulk native defects typically associated with growth quality. The nanoscale depth dependence of the noncontact, nondestructive LEEN technique enables detection of this competitive recombination channel within a few nanometers of the “buried” heterojunction interfaces. © 1999 American Institute of Physics.
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73.61.Ey III-V semiconductors
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
73.20.Fz Weak or Anderson localization

Recombination balance in green-light-emitting GaN/InGaN/AlGaN quantum wells

Petr G. Eliseev, Marek Osin’ski, Hua Li, and Irina V. Akimova

Appl. Phys. Lett. 75, 3838 (1999); http://dx.doi.org/10.1063/1.125473 (3 pages) | Cited 25 times

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Recombination balance parameters for GaN/InGaN/AlGaN single-quantum-well green-lightemitting diodes are extracted from optical power and carrier lifetime measurements. The radiative recombination coefficient B is found to depend on two-dimensional carrier density N, with a low-carrier-density limit of B0 = 1.2×10−4 cm2/s. Sublinearity of the light–current characteristic at temperatures ≥ 300 K is associated with a nonradiative process whose rate is proportional to ∼ N4.8. The external quantum efficiency of 5.5% at 20 mA results from the internal quantum yield of 63% and the photon extraction efficiency of 8.7%. At low temperatures, a nonradiative loss term proportional to ∼ N9 is also identified. © 1999 American Institute of Physics.
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85.60.Jb Light-emitting devices
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

High fluence ultrafast dynamics of semiconductor saturable absorber mirrors

P. Langlois, M. Joschko, E. R. Thoen, E. M. Koontz, F. X. Kärtner, E. P. Ippen, and L. A. Kolodziejski

Appl. Phys. Lett. 75, 3841 (1999); http://dx.doi.org/10.1063/1.125474 (3 pages) | Cited 8 times

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The ultrafast nonlinear dynamics of InGaAs/InP semiconductor saturable absorber mirrors are investigated using reflective pump–probe measurements. At high fluence, ultrafast induced absorption begins to dominate over absorption bleaching. Above the InGaAs quantum well band gap, the differential reflectivity shows a ∼1 ps transient due to nonequilibrium carrier dynamics. Below band gap, the signal is dominated by a strong two-photon absorption component followed by induced absorption that decays with a time constant of ∼5 ps; these components are attributed to nonlinear absorption and subsequent carrier diffusion in the InP layer. © 1999 American Institute of Physics.
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42.50.Md Optical transient phenomena: quantum beats, photon echo, free-induction decay, dephasings and revivals, optical nutation, and self-induced transparency
42.79.Bh Lenses, prisms and mirrors
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
78.47.-p Spectroscopy of solid state dynamics
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
78.66.Fd III-V semiconductors

Correlation of end-of-range damage evolution and transient enhanced diffusion of boron in regrown silicon

L. S. Robertson, M. E. Law, K. S. Jones, L. M. Rubin, J. Jackson, P. Chi, and D. S. Simons

Appl. Phys. Lett. 75, 3844 (1999); http://dx.doi.org/10.1063/1.125475 (3 pages) | Cited 14 times

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Amorphization of a n-type Czochralski wafer was achieved using a series of Si+ implants of 30 and 120 keV, each at a dose of 1×1015 cm2. The Si+ implants produced a 2400 Å deep amorphous layer, which was then implanted with 4 keV 1×1014/cm2 B+. Postimplantation anneals were performed in a tube furnace at 750 °C, for times ranging from 15 min to 6 h. Secondary ion mass spectrometry was used to monitor the dopant diffusion after annealing. Transmission electron microscopy (TEM) was used to study the EOR defect evolution. Upon annealing, the boron peak showed no clustering, and TED was observed in the entire boron profile. TEM results show that both {311} defects and dislocation loops were present in the EOR damage region. The majority of the {311} defects dissolved in the interval between 15 min and 2 h. Results indicate that {311} defects release interstitials during the time that boron exhibits TED. These results show that there is a strong correlation between {311} dissolution in the EOR and TED in the regrown silicon layer. Quantitative TEM of dislocation loop growth and {311} dissolution indicates that in addition to {311} defects, submicroscopic sources of interstitials may also exist in the EOR which may contribute to TED. © 1999 American Institute of Physics.
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66.30.J- Diffusion of impurities
61.72.uf Ge and Si
61.80.Jh Ion radiation effects
61.82.Fk Semiconductors
61.72.J- Point defects and defect clusters
61.72.Yx Interaction between different crystal defects; gettering effect
61.72.Cc Kinetics of defect formation and annealing
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
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