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  • 1
    Electronic Resource
    Electronic Resource
    The effect of InP substrate misorientation on GaInAs-AlInAs interface and alloy quality (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 3476-3480 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The quality of GaInAs-AlInAs epitaxial layers is found to be critically dependent on the degree of (100)-InP substrate misorientation. The alloy quality of both materials is improved when the substrate is misoriented 4° off the (100). The heterojunction interface quality as determined by the full width at half-maximum of quantum-well photoluminescence is also improved when a substrate misoriented by 4° is used. A degradation of both alloy and interface quality as compared to material on (100) InP is observed when the misorientation is 2°. These effects are also observed for strained quantum-well structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341482
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  • 2
    Electronic Resource
    Electronic Resource
    Effective band gap inhomogeneity and piezoelectric field in InGaN/GaN multiquantum well structures (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 2006-2008 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The emission mechanisms of strained InxGa1−xN quantum wells (QWs) were shown to vary depending on the well thickness, L, and x. The absorption edge was modulated by the quantum confined Stark effect and quantum confined Franz-Keldysh effect (QCFK) for the wells, in which, for the first approximation, the product of the piezoelectric field, FPZ, and L exceed the valence band discontinuity, ΔEV. In this case, holes are confined in the triangular potential well formed at one side of the well producing the apparent Stokes-like shift. Under the condition that FPZ×L exceeds the conduction band discontinuity ΔEC, the electron-hole pair is confined at opposite sides of the well. The QCFK further modulated the emission energy for the wells with L greater than the three dimensional free exciton Bohr radius aB. On the other hand, effective in-plane localization of carriers in quantum disk size potential minima, which are produced by nonrandom alloy compositional fluctuation enhanced by the large bowing parameter and FPZ, produces a confined electron-hole pair whose wave functions are still overlapped (quantized excitons) provided that L〈aB. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122350
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  • 3
    Electronic Resource
    Electronic Resource
    Microstructure of GaN laterally overgrown by metalorganic chemical vapor deposition (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 747-749 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Extended defect reduction in GaN grown by lateral epitaxial overgrowth (LEO) on large-area SiO2/GaN/Al2O3 wafers by low pressure metalorganic chemical vapor deposition is characterized using transmission electron microscopy and atomic force microscopy. The laterally overgrown GaN (LEO GaN) has a rectangular cross section with smooth (0001) and {112¯0} facets. The density of mixed-character and pure edge threading dislocations in the LEO GaN (〈5×106 cm−2) is reduced by at least 3–4 orders of magnitude from that of bulk GaN (∼1010 cm−2). A small number of edge dislocations with line directions parallel to the basal plane are generated between the bulk-like overgrown GaN and the LEO GaN regions as well as at the intersection of adjacent merging LEO GaN stripes. The edge dislocations are most likely generated to accommodate the small misorientation between bulk-like GaN and LEO GaN regions as well as between adjacent single-crystal LEO GaN stripes. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121988
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  • 4
    Electronic Resource
    Electronic Resource
    GaxIn1−xAs/AlAs resonant tunneling diodes grown by atmospheric pressure metalorganic chemical vapor deposition (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 2159-2161 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on the growth of GaxIn1−xAs/AlAs double-barrier heterostructures on InP and the fabrication of GaxIn1−xAs/AlAs resonant tunneling diodes (RTDs) by metalorganic chemical vapor deposition (MOCVD). High resolution x-ray diffraction measurements were used to evaluate the heterostructure interface quality. The RTDs achieved a room-temperature peak to valley ratio of 7.7:1 with peak current density of 9.6×104 A/cm2. These are the best reported room-temperature results for any reported RTDs grown by MOCVD. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.112748
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of doping variations on electron transport in GaAs n+-n-n+ structures (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 5695-5701 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Electron transport properties in GaAs n+-n-n+ structures with varying doping profiles (in the direction of electron transport) are investigated using self-consistent ensemble Monte Carlo simulations. In particular, we study the effects of ramp doping [i.e., linearly increasing (ramp-up) or decreasing (ramp-down) doping density within the n region] and spike doping (i.e., introducing one or more n+ spikes in the n region) on electron transport to assess differences, advantages, and potential applications of these doping profiles on device performance. Underlying physical mechanisms for electron transport in these structures are analyzed. Simulation results reveal that overall electron transport can be improved significantly by employing ramp-up (rather than ramp-down) doping and multispike (instead of single-spike) doping schemes. Potential advantages of variable doping in field-effect transistor applications include enhanced current drive capability, reduced source resistance, and improved breakdown characteristics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351920
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  • 6
    Electronic Resource
    Electronic Resource
    Metalorganic chemical vapor deposition of GaN on Si(111): Stress control and application to field-effect transistors (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 7846-7851 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Two schemes of nucleation and growth of gallium nitride on Si(111) substrates are investigated and the structural and electrical properties of the resulting films are reported. Gallium nitride films grown using a 10–500 nm-thick AlN buffer layer deposited at high temperature (∼1050 °C) are found to be under 260–530 MPa of tensile stress and exhibit cracking, the origin of which is discussed. The threading dislocation density in these films increases with increasing AlN thickness, covering a range of 1.1 to 〉5.8×109 cm−2. Films grown using a thick, AlN-to-GaN graded buffer layer are found to be under compressive stress and are completely crack free. Heterojunction field effect transistors fabricated on such films result in well-defined saturation and pinch-off behavior with a saturated current of ∼525 mA/mm and a transconductance of ∼100 mS/mm in dc operation. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1372160
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  • 7
    Electronic Resource
    Electronic Resource
    Metalorganic chemical vapor deposition of high mobility AlGaN/GaN heterostructures (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 5850-5857 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this article, we discuss parameters influencing (a) the properties of thin AlxGa1−xN layers grown by metalorganic chemical vapor deposition and (b) the electrical properties of the two-dimensional electron gas (2DEG) forming at the AlxGa1−xN/GaN heterojunction. For xAl〉0.3, the AlxGa1−xN layers showed a strong tendency towards defect formation and transition into an island growth mode. Atomically smooth, coherently strained AlxGa1−xN layers were obtained under conditions that ensured a high surface mobility of adsorbed metal species during growth. The electron mobility of the 2DEG formed at the AlxGa1−xN/GaN interface strongly decreased with increasing aluminum mole fraction in the AlxGa1−xN layer and increasing interface roughness, as evaluated by atomic force microscopy of the surfaces prior to AlxGa1−xN deposition. In the case of modulation doped structures (GaN/AlxGa1−xN/AlxGa1−xN:Si/AlxGa1−xN), the electron mobility decreased with decreasing thickness of the undoped spacer layer and increasing silicon doping. The electron mobility was only moderately affected by the dislocation density in the films and independent of the growth temperature of the AlxGa1−xN layers at xAl=0.3. For Al0.3Ga0.7N/GaN heterojunctions, electron mobility values up to 1650 and 4400 cm2/V s were measured at 300 and 15 K, respectively. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.371602
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of scattering by strain fields surrounding edge dislocations on electron transport in two-dimensional electron gases (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 64-66 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present a theory of deformation potential carrier scattering of two-dimensional electron gases from the strain fields surrounding edge dislocations. The scattering rate is evaluated in closed form without any fitting parameters. The result is directed towards understanding mobility limiting scattering mechanisms for two-dimensional electron gases at AlGaN/GaN heterointerfaces. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1429758
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  • 9
    Electronic Resource
    Electronic Resource
    Indium-surfactant-assisted growth of high-mobility AlN/GaN multilayer structures by metalorganic chemical vapor deposition (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 3449-3451 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: AlN/GaN single and multilayer structures with various AlN and GaN layer thicknesses were grown by metalorganic chemical vapor deposition. Step flow growth of AlN was achieved using trimethylindium as a surfactant. Defect formation in the AlN layer could be largely prevented for AlN layers thinner than 2.9 nm. In the multiquantum-well samples, which consisted of five (AlN/GaN) periods, a two-dimensional electron gas (2DEG) was formed at the interface between the GaN base layer and the first AlN barrier layer. When the thickness of the AlN barrier layer in the multiquantum well was increased from 0.9 to 2.6 nm at a constant GaN well thickness of 5 nm, the sheet carrier density of the 2 DEG increased from 5×1012 to 2.1×1013 cm−2 and the electron mobility measured at 77 K decreased from 11780 to 3140 cm2/V s. The effect of the GaN well thickness was also investigated. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1420573
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  • 10
    Electronic Resource
    Electronic Resource
    Dislocation reduction in GaN films through selective island growth of InGaN (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 2665-2667 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Dislocation reduction in GaN films grown on sapphire and silicon substrates was achieved by inserting thin InGaN layers grown in a selective island growth mode after partial passivation of the GaN surface with a submonolayer of silicon nitride. We show that this technique is most effective at reducing the pure edge dislocation density when it is high (i.e., 〉1010 cm−2) and less when the density is in the 108–109 cm−2 range. Thus, the structural quality of typically highly dislocated GaN on silicon films could be significantly improved, visible in a reduction of the (0002) full width at half maximum (FWHM) from 1300 arcsec for ordinary GaN on silicon to 800 arcsec for GaN films with silicon nitride/InGaN interlayers. In the case of GaN layers grown on sapphire (dislocation density ∼109 cm−2), the method resulted mainly in a reduction of the FWHM of the (101¯2) and (202¯1) diffraction peaks. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1319528
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