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  • 1
    Electronic Resource
    Electronic Resource
    Characterization of GaAs/AlGaAs heterojunction bipolar transistor devices using photoreflectance and photoluminescence (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 6160-6163 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Photoreflectance (PR) and photoluminescence (PL) techniques were used to characterize the AlGaAs/GaAs heterojunction bipolar transistor (HBT) wafers grown by molecular beam epitaxy (MBE). The line shape of the PR GaAs signal is closely related to the cleanliness of the MBE system. The Franz–Keldysh oscillations of the GaAs signal become sharper, well defined, and the oscillation amplitude increases slightly as the MBE system is cleaned up. The dc current gain of the HBT devices was observed to increase accordingly. The origin for this correlation is discussed. The PL spectra of the HBT device wafers indicate that the intensity of the free-to-bound transition corresponding to the donor to valence band becomes strong in high gain device wafers. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.371669
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  • 2
    Electronic Resource
    Electronic Resource
    Photoreflectance study of pseudomorphic high electron mobility transistors (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 82 (1997), S. 2607-2610 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Room temperature photoreflectance (PR) measurements have been carried out on a series of pseudomorphic AlGaAs/InGaAs/AlGaAs high electron mobility transistor (HEMT) structures with different doping profiles grown by molecular beam epitaxy. The GaAs and AlGaAs features in the PR spectrum were studied and their origins were determined by a sequential etching method. It was found that the GaAs buffer layer and AlGaAs barrier layer dominate the GaAs and AlGaAs features in the PR spectrum, respectively. The electric fields for Franz-Keldish oscillations (FKOs) associated with the E0 transition of both GaAs and AlGaAs are affected by the doping on both sides of the InGaAs channel, but are not directly related to the channel carrier concentration. The aluminum composition in the AlxGa1−xAs layers was determined and compared with the results of FKO energy and the critical-point energy methods. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.366074
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  • 3
    Electronic Resource
    Electronic Resource
    Photooxidative damage to the photosynthetic apparatus during chilling (1980)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 50 (1980), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Short periods of chilling in the presence of light (up to 6 h: 1°C; 270 W/m2) decreased the subsequent apparent photosynthesis and chlorophyll fluorescence of leaf discs of Cucumis sativus L. cv. Kleine Groene Scherpe. The extent of the injury depended on the duration of the chilling pretreatment. After 6 h the subsequent apparent photosynthesis even reached a negative value, and it increased only slightly during the next 2 1/2 h. The decrease of apparent photosynthesis was not a consequence of increased dark respiration but was of photooxidative origin since the presence of both light and oxygen was required. Preincubation in the light for 2 h at 20°C sensitized leaf discs to subsequent photooxidation during chilling. Prompt and delayed chlorophyll fluorescence decreased simultaneously after chilling and light treatment. The corresponding decrease of photosynthesis and chlorophyll fluorescence is discussed in relation to primary photooxidative damage to the photosystems in the chloroplast membrane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1980.tb02683.x
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  • 4
    Electronic Resource
    Electronic Resource
    Psilostachyin A (1988)
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 44 (1988), S. 1221-1223 
    Details
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108270188002768
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