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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Il nuovo cimento della Società Italiana di Fisica 2 (1983), S. 1944-1949 
    ISSN: 0392-6737
    Keywords: Studies of specific magnetic materials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Riassunto Si sono fatte misurazioni degli spettri di assorbimento di film sottili di HgCr2Se4 da 295 K a 25 K nell'intervallo di energia fotonica da 0.5 eV a 2.5 eV. Appare evidente che esiste un'ampia banda di assorbimento con un massimo a circa 0.93 eV a 295 K. Questa banda di assorbimento mostra uno spostamento nel rosso con la diminuzione della temperatura in corrispondenza della transizione dalla banda di valenza alla stretta banda di conduzione. Inoltre si trova che esistono altre transizioni con gap di energia di 1.20, 1.47 e 1.90 eV a 295 K. Come risultato di questa ricerca, si evidenzia la possibilità di costruire laser accordabili da questo materiale.
    Abstract: Резюме Проведены измерения спектров поглощения для тонких пленок HgCr2Se4 в области температур от 295 до 25 К с жнергией фотонов от 0.5 до 2.5 зВ. Показано, что существует сирокая полоса поглощения с максимумом вблизи 0.93 зВ при 295 К. Жта полоса поглощения обнаруживает явление красного смещения с уменьшением температуры, соответсвующей переходу из валентной зоны в узкую зону проводимости. Кроме того, мы обнаружили, что существуют другие переходы 1.20, 1.47, и 1.90 зВ при 295 К. На основе проведенного исследования мы указываем на возможность создания перестраиваемых лазеров на жтом материале.
    Notes: Summary Measurements of the absorption spectra for thin films of HgCr2Se4 were made from 295 K to 25 K in the photon energy range from 0.5 eV to 2.5 eV. It becomes evident that there exists a broad absorption band with a maximum at about 0.93 eV at 295 K. This absorption band shows a red-shift phenomenon with decreasing temperature corresponding to the transition from the valence band to the narrow conduction band. Furthermore, we find out that there exist other transitions with energy gaps of 1.20, 1.47 and 1.90 eV at 295 K. As a result of this investigation we point out the possibility of making tunable lases from this material.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Il nuovo cimento della Società Italiana di Fisica 2 (1983), S. 1798-1802 
    ISSN: 0392-6737
    Keywords: Studies of specific magnetic materials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Riassunto Film policristallini sottili di semiconduttore HgCr2Se4 sono stati preparati per la prima volta su substrati isolanti di cristalli singoli MgAl2O4 mediante deposizione a raggi molecolari e successiva tempra con HgSe. Si sono ottenute le condizioni ottimali per preparare film sottili a fase singola di HgCr2Se4. La resistenza magnetica e gli effetti di Hall di questi film sono stati misurati da 77 a 295 K in campi magnetici fino a 1.19·106 A/m. Diventa evidente che queste proprietà elettriche dei film sono influenzate da strati di interdiffusione nei film vicino ai substrati o dagli strati in disordine magnetico come i bordi amorfo o del grano in film.
    Abstract: Резюме Впервые приготовлены поликристаллические тонкие пленки ферромагнитных полупроводников HgCr2Se на непроводящих монокристаллических подложках MgAl2O4 с помощью осаждения молекулярного пучка и последующего отжига с HgSe. Определяются оптимальные условия для приготовления тонких пленок HgCr2Se4, имеющих единственную фазу. Измеряются, магниторезистивный эффект и эффект Холла для этих пленок в области температур от 77 до 295 К и при магнитных полях вплоть до 1.19·106 А/м. Отмечается, что на электрические свойства этих пленок влияют слои в пленках вблизи подложки или магнитноразупорядоченные слои, такие как аморфные или зернистые границы в пленках.
    Notes: Summary Polycrystalline thin films of the ferromagnetic semiconductor HgCr2Se4 have been prepared for the first time on insulating MgAl2O4 single-crystal substrates by molecular-beam deposition and subsequent annealing with HgSe. The optimum conditions for preparing single-phase thin films of HgCr2Se4 were obtained. The magnetoresistance and Hall effects of these films were measured from 77 to 295 K in magnetic fields up to 1.19·106 A/m. It becomes evident that these electrical properties of the films are affected by the interdiffusion layers in the films near the substrates or the magnetically disordered layers such as amorphous or grain boundaries in the films.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Physics and Chemistry of Solids 41 (1980), S. 1279-1284 
    ISSN: 0022-3697
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 81 (2002), S. 613-615 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present picosecond time resolved photoluminescence measurements of GaAs/AlGaAs quantum dot structures—grown by modified droplet epitaxy—where no wetting layer is connecting the dots. We find a fast carrier relaxation time (30 ps) to the dot ground state, which becomes even faster for increasing the photogenerated carrier injection. This shows that the two–dimensional character of the wetting layer is not relevant in determining the quantum dot capture, in contrast with the conclusions of several models so far presented in literature. We discuss the role of the barrier states as well as the possibility of Auger processes involving the zero-dimensional levels of the quantum dots. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 799-800 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Pb1−x−yCdxSry S/PbS/Pb1−x−yCdxSryS double-heterostructure lasers emitting at a midinfrared wavelength region were fabricated for the first time using molecular beam epitaxy. Effects of the lattice mismatches between active and confinement layers and also between substrate and confinement layers using a tilted substrate on the laser properties were investigated. The maximum pulsed operating temperature increases as the lattice mismatch decreased using a tilted substrate.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Crystal Growth 111 (1991), S. 688-692 
    ISSN: 0022-0248
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Crystal Growth 95 (1989), S. 599-602 
    ISSN: 0022-0248
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Crystal Growth 81 (1987), S. 400-404 
    ISSN: 0022-0248
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Surface Science 296 (1993), S. 199-212 
    ISSN: 0039-6028
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Surface Science 267 (1992), S. 241-244 
    ISSN: 0039-6028
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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