The p-n conduction type transition in Ge-incorporated Bi2Te3 thermoelectric materials

Wu, Hsin‐Jay; Chen, Bo Yu; Cheng, Hao

doi:10.1016/j.actamat.2016.09.043

Cited by 39 publications

(11 citation statements)

References 27 publications

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“…In this work, we determine the phase diagram of the ternary Bi–Te–Ga system at 523 K by experiments, aiming to depict the utmost solubility of Ga in single-phase Bi 2 Te 3 . Similar to our previous studies, , the Ga-incorporated Bi 2 Te 3 also experiences the p- to n-type transition with increasing dopant concentration. Moreover, the p–n transition zone point coincides well with the phase boundary separating the single-phase Bi 2 Te 3 and the neighboring multiple-phase regions.…”

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confidence: 89%

“…It is noteworthy that the multicomponent high- zT alloys generally having their compositions fall in the narrow and specific regions where PF and κ attain the optimal balance. A phase diagram could be viewed as a compass that navigates toward those high- zT zones. − Notwithstanding the importance, the phase diagram of the Bi–Te–Ga ternary system is still left unavailable. In this work, we determine the phase diagram of the ternary Bi–Te–Ga system at 523 K by experiments, aiming to depict the utmost solubility of Ga in single-phase Bi 2 Te 3 .…”

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confidence: 99%

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Unravelling p–n Conduction Transition in High Thermoelectric Figure of Merit Gallium-Doped Bi₂Te₃ via Phase Diagram Engineering

Lin

Yen²,

Tsai³

et al. 2020

ACS Appl. Energy Mater.

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We revisit the well-established Bi2Te3 via phase diagram engineering. Along with a phase diagram in hand, it is realized that the solubility of Ga in Bi2Te3 is coincident with the p–n transition zone in Ga–Bi2Te3 alloys. The best-performing n-type (Bi2Te3)0.93(Ga2Te5)0.07 possesses a peak zT ∼ 1.5 at 300 K, which is attributed to the reduced κ ∼ 1.8 W m–1 K–1 and the low-lying ρ. The p-type Bi1.99Ga0.01Te3 also exhibits a peak zT of 1.2 at 300 K. In other words, the addition of Ga leads to high-zT p-type or n-type bismuth-tellurides, which simplifies the conventional synthesis route that usually involves different dopants.

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confidence: 89%

mentioning

confidence: 99%

Unravelling p–n Conduction Transition in High Thermoelectric Figure of Merit Gallium-Doped Bi₂Te₃ via Phase Diagram Engineering

Lin

Yen²,

Tsai³

et al. 2020

ACS Appl. Energy Mater.

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“…This leads to a shift of the valence and conduction band edges to lower energies with increasing Bi content 19 . In addition, a reverse change in the p-to-n conduction type has also been observed in Bi-doped thermoelectric Ge-Te-Bi materials 20 , resulting in the composition-dependent Seebeck coefficient changing from positive to negative with respect to the doping concentration.…”

Section: Introductionmentioning

confidence: 94%

Conversion of p–n conduction type by spinodal decomposition in Zn-Sb-Bi phase-change alloys

et al. 2020

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Phase-change films with multiple resistance levels are promising for increasing the storage density in phase-change memory technology. Diffusion-dominated Zn 2 Sb 3 films undergo transitions across three states, from high through intermediate to low resistance, upon annealing. The properties of the Zn 2 Sb 3 material can be further optimized by doping with Bi. Based on scanning transmission electron microscopy combined with electrical transport measurements, at a particular Bi concentration, the conduction of Zn-Sb-Bi compounds changes from p-to n-type, originating from spinodal decomposition. Simultaneously, the change in the temperature coefficient of resistivity shows a metal-toinsulator transition. Further analysis of microstructure characteristics reveals that the distribution of the Bi-Sb phase may be the origin of the driving force for the p-n conduction and metal-to-insulator transitions and therefore may provide us with another way to improve multilevel data storage. Moreover, the Bi doping promotes the thermoelectric properties of the studied alloys, leading to higher values of the power factor compared to known reported structures. The present study sheds valuable light on the spinodal decomposition process caused by Bi doping, which can also occur in a wide variety of chalcogenide-based phase-change materials. In addition, the study provides a new strategy for realizing novel p-n heterostructures for multilevel data storage and thermoelectric applications.

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“…On further increasing the temperature electrons become the majority carriers (n-type) [25]. Another reason for a p–n-type transition is Ge substituting Bi/Te in Bi 2 Te 3 [26]. Our XRD does not show any phase transition.…”

Section: Resultsmentioning

confidence: 82%

“…There is transition of from p-type to n-type behavior with increasing temperature which may be attributed to bipolar diffusion [25–26] and phase transitions [27–28]. In the chalcogenide AgBiSe 2 , there is an exchange of Ag and Bi atoms in the lattice during the phase transition from rhombohedral to cubic that results in the change from p-type to n-type behavior.…”

Section: Resultsmentioning

confidence: 99%

Enhancement in thermoelectric properties due to Ag nanoparticles incorporated in Bi₂Te₃ matrix

Gupta¹,

Agarwal²,

Bathula³

et al. 2019

Beilstein J. Nanotechnol.

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The present study aims to see the enhancement in thermoelectric properties of bismuth telluride (Bi2Te3) annealed at different temperatures (573 and 773 K) through silver (Ag) nano-inclusions (0, 2, 5, 10, 15 and 20 wt %). Transmission electron microscopy (TEM) images of Ag incorporated in Bi2Te3 annealed at 573 K shows tubular, pentagonal, trigonal, circular and hexagonal nanoparticles with sizes of 6–25 nm (for 5 wt % Ag ) and 7–30 nm (for 20 wt % Ag). Ag incorporated in Bi2Te3 annealed at 773 K shows mainly hexagonally shaped structures with particle sizes of 2–20 nm and 40–80 nm (for 5 wt % Ag) and 10–60 nm (for 20 wt % Ag). Interestingly, the samples annealed at 573 K show the highest Seebeck coefficient (S, also called thermopower) at room temperature (p-type behavior) for 5% Ag which is increased ca. five-fold in comparison to Ag-free Bi2Te3, whereas for samples with the same content (5% Ag) annealed at 773 K the increment in thermopower is only about three-fold with a 6.9-fold enhancement of the power factor (S 2σ). The effect of size and shape of the nanoparticles on thermoelectric properties can be understood on the basis of a carrier-filtering effect that results in an increase in thermopower along with a control over the reduction in electrical conductivity to maintain a high power factor yielding a high figure of merit.

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The p-n conduction type transition in Ge-incorporated Bi2Te3 thermoelectric materials

Cited by 39 publications

References 27 publications

Unravelling p–n Conduction Transition in High Thermoelectric Figure of Merit Gallium-Doped Bi₂Te₃ via Phase Diagram Engineering

Unravelling p–n Conduction Transition in High Thermoelectric Figure of Merit Gallium-Doped Bi₂Te₃ via Phase Diagram Engineering

Conversion of p–n conduction type by spinodal decomposition in Zn-Sb-Bi phase-change alloys

Enhancement in thermoelectric properties due to Ag nanoparticles incorporated in Bi₂Te₃ matrix

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The p-n conduction type transition in Ge-incorporated Bi2Te3 thermoelectric materials

Cited by 39 publications

References 27 publications

Unravelling p–n Conduction Transition in High Thermoelectric Figure of Merit Gallium-Doped Bi2Te3 via Phase Diagram Engineering

Unravelling p–n Conduction Transition in High Thermoelectric Figure of Merit Gallium-Doped Bi2Te3 via Phase Diagram Engineering

Conversion of p–n conduction type by spinodal decomposition in Zn-Sb-Bi phase-change alloys

Enhancement in thermoelectric properties due to Ag nanoparticles incorporated in Bi2Te3 matrix

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Unravelling p–n Conduction Transition in High Thermoelectric Figure of Merit Gallium-Doped Bi₂Te₃ via Phase Diagram Engineering

Unravelling p–n Conduction Transition in High Thermoelectric Figure of Merit Gallium-Doped Bi₂Te₃ via Phase Diagram Engineering

Enhancement in thermoelectric properties due to Ag nanoparticles incorporated in Bi₂Te₃ matrix