Photo-Induced conductivity of heterojunction GaAs/Rare-Earth doped SnO2

Bueno, Cristina de Freitas; Machado, Diego Henrique de Oliveira; Pineiz, Tatiane de Fátima; Scalvi, Luís Vicente de Andrade

doi:10.1590/s1516-14392013005000060

Cited by 3 publications

(4 citation statements)

References 30 publications

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“…The decay for the heterojunction GaAs/SnO 2 :2%Eu, thermally annealed at 200°C/1 h (sample H1), is shown in the main Figure 1, whereas the decay for the heterojunction treated at 400°C/20 min (sample H2) is shown in the inset of Figure 2. source assures energies lower than 1.65 eV, with no electron-hole pair generated in the SnO 2 (top) layer, and only intrabandgap levels of SnO 2 are excited.However, if the intensity is high enough, the light may penetrate into the GaAs layer and generate electron-hole pairs in this material. Besides, there is possibility of excitation of the 2DEG[17,30].Figure 3illustrates this situation, showing on the right side the ionization of impurities in the SnO 2 layer (top), which present a distribution of energy levels (due to disordered neighborhood), the possibility of 2DEG formation at GaAs/SnO 2 interface (center), and the electron-hole generation in the GaAs layer (bottom). The electrical current in the excitation lamp was 5.5 A (low intensity) and the excitation time was 6 min.…”

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confidence: 82%

On the electrical properties of distinct Eu3+ emission centers in the heterojunction GaAs/SnO2

Bueno

Scalvi

2016

Thin Solid Films

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GaAs/SnO 2 :2%Eu heterojunctions are deposited by resistive evaporation and sol-gel-dip-coating techniques respectively, with the top layer thermally annealed at different temperatures. The sample annealed at 200°C/1 h has a much higher conductivity and a lower deepest level (79 meV) than the sample annealed at 400 o C/20 min, for which the deepest level value is 98 meV. The decay of photo-induced current at room temperature for these heterojunctions shows a decay of 48.8% from the initial value for a sample annealed at 200°C/1 h, compared to a decay of 54.2% from the initial value for a sample treated at 400 o C/20 min. The excitation source has a broad band with energy lower than 1.65 eV, assuring that no electron-hole pair is generated in the SnO 2 (top) layer. The data fitting seems to indicate that, although the grain boundary scattering dominates the mobility, the inclusion of time dependent terms is needed, such as multi-center capture or ionized impurity scattering. Photoluminescence data shows that the main Eu 3+ transition changes from 5 D 0 → 7 F 2 (related to ions located at asymmetric sites such as boundary layer) to 5 D 0 → 7 F 1 (related to ions located at symmetric sites), as the annealing temperature is increased.

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confidence: 82%

On the electrical properties of distinct Eu3+ emission centers in the heterojunction GaAs/SnO2

Bueno

Scalvi

2016

Thin Solid Films

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“…The most remarkable uses of GaAs cover photovoltaics, heterostructures, semiconductor lasers, light-emitting diodes and solar cells [2][3][4][5][6][7][8][9][10] . GaAs has several phases and crystallizes in the cubic zinc blend phase (B3) at ambient conditions.…”

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confidence: 99%

“…orthorhombic Omm2 phase above 25 GPa and hexagonal cinnabar phase between 60GPa and 80 GPa) [2][3][4][5][6][7][8][9][10][11] are not the focus of our study. Apart from many experimental efforts 4,10 , Rino et al 12 calculated phase transition pressure (P T ) as 22 GPa [7][8][9][10][11][12] have extreme motivation on P T , cubic elastic constants and bulk modulus. However, pressure depence of young modulus, shear modulus, elastic wave velocities, Poisson ratio, elastic anisotropy, Kleinman parameter, anisotropy degree are still lacking for GaAs except the analysis of Varshney et al 11 .…”

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confidence: 99%

Phase transition and elasticity of gallium arsenide under pressure

Güler

2014

Mat. Res.

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Geometry optimization calculations were performed for some structural, elastic and mechanical properties of gallium arsenide (GaAs) under pressures up to 25 GPa. On contrast to previous works, a recent Stillinger-Weber type potential was used for the first time to elaborate the pressure dependence aspects of GaAs. B3→B1 phase transition pressure was determined as 17 GPa. Pressure dependence of density, typical cubic elastic constants, bulk, shear, and Young moduli, Poisson ratio, elastic velocities, anisotropy parameter, Kleinman parameter, elastic anisotropy degree, and stability conditions of GaAs were also evaluated. Dverall, our results are satisfactory and can be helpful for future investigations of GaAs under pressure.

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“…These Ce 3+ ions, which act as acceptors in SnO 2 , can trap electrons coming from the ionization of electron-hole pairs in the GaAs layer. Again, holes recombine with the electrons in the SnO 2 layer which is naturally n-type, the overall effect is a decrease in conductivity of the sample [38]. Figure 8 shows current-voltage measurements to the heterojunction sample GS4 (which has the reverse order of deposition as compared to sample SG1, of Fig.…”

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confidence: 99%