Space-Charge Currents in n-Type GaAs

Yamashita, Akiyasu

doi:10.1143/jjap.6.117

Cited by 4 publications

(4 citation statements)

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“…The decrease of e with increasing carrier concentration is much larger than that of h . The values of h in SiGe measured in the present work are close to those in polycrystalline SiGe reported by other groups 2, 11,14 and are clearly lower than that in Si. 15 No systematic effect of different dopant species, such as Ga, In, or B, in p-type crystals can be detected explicitly.…”

Section: Resultssupporting

confidence: 89%

Temperature dependence of electron and hole mobilities in heavily impurity-doped SiGe single crystals

Yonenaga

Akashi

et al. 2005

Journal of Applied Physics

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Heavily impurity-doped single crystals of Si x Ge 1−x alloy with the composition 0.84Ͻ x Ͻ 1 and large-grained polycrystals with x = 0.80 were grown by the Czochralski technique. The Hall-coefficient measurements of the electron and hole mobilities in the grown crystals were carried out in the temperature range of 300-1000 K and compared with those in undoped SiGe. The Hall mobilities of electrons and holes in SiGe with a carrier concentration of 10 19 -10 20 cm −3 both show a T n , n ϳ 1, temperature dependence up to elevated temperatures. This indicates that the carrier transport process is mainly rate controlled by charged impurity scattering. In single-crystal SiGe free from grain-boundary effects, the hole mobility increases with decreasing Si content at least up to 0.84 and the electron mobility is greater than in Si and polycrystalline SiGe. These results suggest that scattering processes in alloy semiconductors are more complicated than previously thought.

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Section: Resultssupporting

confidence: 89%

Temperature dependence of electron and hole mobilities in heavily impurity-doped SiGe single crystals

Yonenaga

Akashi

et al. 2005

Journal of Applied Physics

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“…The bands are assigned to the intraionic transitions in the isolated Cu ϩ ions as described in earlier works. 3,14 In order to investigate the emission behavior of CaS:Pb, Cu samples, a PL excitation ͑PLE͒ study was carried out. Figure 3 shows PLE spectra of the CaS:Pb, Cu containing 1.0 atom % Cu probed at 430 nm.…”

Section: Resultsmentioning

confidence: 99%

“…1,2 Among the numerous compounds of phosphors available, luminescent center ion-doped alkaline-earth sulfides have been extensively investigated due to their high luminescent yields. [3][4][5] Thin films of phosphor materials offer significant advantages over conventional bulk powders for display applications, such as higher resolution, more uniform density, and increased thermal stability, etc. However, polycrystalline thin-film phosphors are known to exhibit noticeably lower luminescent output than their bulk powder.…”

mentioning

confidence: 99%

“…[7][8][9] Although the correct mechanism of the luminescent transition of CaS:Cu has not been determined, the fact that CaS:Cu exhibited efficient PL and cathodoluminescence ͑CL͒ indicates that the main reason for poor EL performance of CaS:Cu could be poor excitation efficiency under EL excitation conditions. 3,7,8,10 Therefore, improvement of EL performance was attempted by changing the structure of a CaS:Pb EL device which had exhibited efficient EL. 11 CaS:Pb has been known to exhibit efficient blue PL.…”

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confidence: 99%

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Cathodoluminescence and Photoluminescence Properties of CaS Thin Film Codoped with Pb and Cu

Choi

Park

Park³

et al. 2004

J. Electrochem. Soc.

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Luminescent properties of CaS thin films doped with Pb and Cu have been investigated. Under UV and low-voltage electron-beam excitation, the CaS:Pb, Cu thin films exhibited highly saturated blue photoluminescence centered at 430 nm and cathodoluminescence peaked at 415-425 nm at room temperature. Spectroscopic study on CaS:Pb, Cu revealed that the emission characteristics were identical to CaS:Cu, although the excitation spectra resembled that of CaS:Pb film. These results demonstrated the efficient energy transfer from Pb to Cu, confirming successful sensitization. However, the efficient energy-transfer process from Pb to Cu could not be explained by the standard energy-transfer theory. Therefore, instead of a Dexter-type energy transfer, a phononassisted process was proposed as a possible coupling mechanism between Cu and Pb ions in CaS.The use of flat panel displays is increasing rapidly in various applications, including mobile, desktop, and home appliances, etc. The luminescent properties and improvement of phosphor materials have also gained renewed attention for flat panel display applications such as electroluminescent ͑EL͒ and field emission displays. 1,2 Among the numerous compounds of phosphors available, luminescent center ion-doped alkaline-earth sulfides have been extensively investigated due to their high luminescent yields. [3][4][5] Thin films of phosphor materials offer significant advantages over conventional bulk powders for display applications, such as higher resolution, more uniform density, and increased thermal stability, etc. However, polycrystalline thin-film phosphors are known to exhibit noticeably lower luminescent output than their bulk powder. 6 It appears that the greatest challenge in the fabrication of sulfide phosphor thin films is the incorporation of the luminescent ions and/or codopants with the correct charge state uniformly within the host lattice. Deficient stoichiometry and poor crystallinity of the host lattice have also been found to affect the luminescent properties of thin-film phosphors. 5 Calcium sulfide ͑CaS͒ and their solid solutions in polycrystalline form have been the subject of much interest for large-area displays. The introduction of rare earth and/or other dopants in these largebandgap host matrices permits them to be tuned as narrow or broadband visible light-emitting phosphors. Although CaS, a wide-gap semiconductor material, has been commercially used as a host material of phosphor and the photoluminescent ͑PL͒ and EL properties of Cu-doped CaS ͑CaS:Cu͒ powders have already been investigated, little work on CaS:Cu thin films has been carried out. [7][8][9] Although the correct mechanism of the luminescent transition of CaS:Cu has not been determined, the fact that CaS:Cu exhibited efficient PL and cathodoluminescence ͑CL͒ indicates that the main reason for poor EL performance of CaS:Cu could be poor excitation efficiency under EL excitation conditions. 3,7,8,10 Therefore, improvement of EL performance was attempted by changing the structure of a CaS:Pb ...

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