ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Reduced thermal conductivity in low-temperature-grown GaAs (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 2325-2327 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Thermal conductivity of low-temperature-grown GaAs(LT GaAs) was measured at room temperature using a self-heated photolithographically patterned platinum wire on the surface of the sample. Finite element calculations were performed to extract the thermal conductivity from the nonlinear I–V characteristic of the wires. For LT GaAs grown at a substrate temperature of 240 °C, the thermal conductivity was found to be only 23% of the value for stoichiometric GaAs. Rapid thermal annealing of the sample at 650 °C for 30 s increased the thermal conductivity to 46% of the GaAs value. Strong phonon scattering by point defects could account for reduced thermal conductivity in the as-grown material. The reduced thermal conductivity in the annealed material, however, is not consistent with our current understanding of the defects in annealed LT GaAs. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123839
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    High-performance (Al,Ga)N-based solar-blind ultraviolet p–i–n detectors on laterally epitaxially overgrown GaN (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 247-249 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Solar-blind ultraviolet photodiodes with a band-edge wavelength of 285 nm were fabricated on laterally epitaxially overgrown GaN grown by metalorganic chemical vapor deposition. Current–voltage measurements of the diodes exhibited dark current densities as low as 10 nA/cm2 at −5 V. Spectral response measurements revealed peak responsivities of up to 0.05 A/W. Response times for these diodes were measured to be as low as 4.5 ns for 90%-to-10% fall time. For comparison, diodes were fabricated using the same p–i–n structure deposited on dislocated GaN. These diodes had dark current densities many orders of magnitude higher, as well as a less sharp cutoff, and a significant slow tail under impulse excitation. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.124337
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Emission mechanisms of bulk GaN and InGaN quantum wells prepared by lateral epitaxial overgrowth (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 1460-1462 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The emission mechanisms of bulk GaN and InGaN quantum wells (QWs) were studied by comparing their optical properties as a function of threading dislocation (TD) density, which was controlled by lateral epitaxial overgrowth. Slightly improved excitonic photoluminescence (PL) intensity was recognized by reducing TD density from 1010 cm−2 to less than 106 cm−2. However, the major PL decay time was independent of the TD density, but was rather sensitive to the interface quality or material purity. These results suggest that TDs simply reduce the net volume of light-emitting area. This effect is less pronounced in InGaN QWs where carriers are effectively localized at certain quantum disk size potential minima to form quantized excitons before being trapped in nonradiative pathways, resulting in a slow decay time. The absence of any change in the optical properties due to reduction of TD density suggested that the effective band gap fluctuation in InGaN QWs is not related to TDs. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123581
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Effects of Si-doping in the barriers of InGaN multiquantum well purplish-blue laser diodes (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 496-498 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Optical gain spectra of InGaN multiquantum well laser diode wafers having Si-doped or undoped InGaN barriers were compared. Although evidence for effective band-gap inhomogeneity was found in both structures, the wells with the Si-doped barriers exhibited a smaller Stokes-like shift. Si doping suppressed emergence of a secondary amplified spontaneous emission peak at 3.05 eV, which was uncoupled with the primary one at 2.93 eV. Furthermore Si doping reduced the threshold power density required to obtain the stimulated emission. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121912
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Piezoelectric surface barrier lowering applied to InGaN/GaN field emitter arrays (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 405-407 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A method of lowering the surface barrier for field emission by using the piezoelectric effect is presented. The piezoelectric effect produces a surface dipole that decreases the surface barrier, which in turn decreases the turn-on voltage of the field emitter. Calculations show that significant reduction of the tunneling barrier can be effected with relatively thin layers of strained InGaN on GaN field emitter arrays. Dramatic reduction of the turn-on voltage from 450 V (GaN field emitter array) to 70 V (InGaN/GaN field emitter array) was observed and can be attributed partly to surface barrier lowering. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121849
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Electrical characterization of GaN p-n junctions with and without threading dislocations (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 975-977 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effect of dislocations on the electrical characteristics of GaN p-n junctions has been examined through current–voltage measurements. Lateral epitaxial overgrowth (LEO) was used to produce areas of low dislocation density in close proximity to areas with the high dislocation density typical for growth on sapphire. A comparison of p-n diodes fabricated in each region reveals that reverse-bias leakage current is reduced by three orders of magnitude on LEO GaN. Temperature-dependent measurements on the LEO diodes indicate that the remaining leakage current in these devices is associated with a deep trap level. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122057
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Growth and characterization of bulk InGaN films and quantum wells (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 3147-3149 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: InGaN bulk layers and single quantum wells were grown by atmospheric pressure metalorganic chemical vapor deposition on c-plane sapphire. We have found that the incorporation efficiency of indium into InGaN epitaxial layers is strongly dependent on the growth rate of the films. Narrow and bright band edge related luminescence was observed for InGaN films up to an indium content of 20% grown at 700 °C. In0.16Ga0.84N single quantum wells with graded InxGa1−xN barriers showed intense luminescence, with an energy shift towards shorter wavelength with decreasing quantum well thickness. The photoluminescence full width at half-maximum of the 50 A(ring) thick well was as low as 7.9 nm (59 meV) at 300 K. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.115806
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...