scholarly journals Overcoming Asymmetric Contact Resistances in Al-Contacted Mg2(Si,Sn) Thermoelectric Legs

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6774
Author(s):  
Julia Camut ◽  
Sahar Ayachi ◽  
Gustavo Castillo-Hernández ◽  
Sungjin Park ◽  
Byungki Ryu ◽  
...  
Keyword(s):  
Density Functional ◽  
Electrical Contact ◽  
Electrical Energy ◽  
Thermoelectric Generators ◽  
Electrical Contact Resistance ◽  
Contact Resistivities ◽  
Hybrid Density Functional ◽  
Role Of Zn ◽  
Asymmetric Contact

Thermoelectric generators are a reliable and environmentally friendly source of electrical energy. A crucial step for their development is the maximization of their efficiency. The efficiency of a TEG is inversely related to its electrical contact resistance, which it is therefore essential to minimize. In this paper, we investigate the contacting of an Al electrode on Mg2(Si,Sn) thermoelectric material and find that samples can show highly asymmetric electrical contact resistivities on both sides of a leg (e.g., 10 µΩ·cm2 and 200 µΩ·cm2). Differential contacting experiments allow one to identify the oxide layer on the Al foil as well as the dicing of the pellets into legs are identified as the main origins of this behavior. In order to avoid any oxidation of the foil, a thin layer of Zn is sputtered after etching the Al surface; this method proves itself effective in keeping the contact resistivities of both interfaces equally low (<10 µΩ·cm2) after dicing. A slight gradient is observed in the n-type leg’s Seebeck coefficient after the contacting with the Zn-coated electrode and the role of Zn in this change is confirmed by comparing the experimental results to hybrid-density functional calculations of Zn point defects.

Exploring the role of vacancy defects in the optical properties of LiMgPO4

2020 ◽  
Vol 22 (28) ◽  
pp. 16244-16257 ◽  
Author(s):  
Pampa Modak ◽  
Brindaban Modak
Keyword(s):  
Density Functional Theory ◽  
Optical Properties ◽  
Electronic Structure ◽  
Density Functional ◽  
Structure Calculation ◽  
Hybrid Density Functional Theory ◽  
Functional Theory ◽  
Vacancy Defects ◽  
Hybrid Density Functional

A systematic electronic structure calculation employing hybrid density functional theory has been carried out to explore the role of all possible vacancy defects in neutral and charged states in the optical properties of LiMgPO4.

Electronic Structure and Contact Resistance at the Interface Between Carbon Nanotubes and Copper Pad

2009 ◽  
Author(s):  
Feng Gao ◽  
Jianmin Qu ◽  
Matthew Yao
Keyword(s):  
Carbon Nanotubes ◽  
Electronic Structure ◽  
Contact Resistance ◽  
Density Functional ◽  
Low Voltage ◽  
Local Density ◽  
Electrical Contact ◽  
Average Density ◽  
Electrical Contact Resistance ◽  
Electrical Interconnects

Due to their unique and superior mechanical and electrical properties, carbon nanotubes (CNTs) are a promising candidate as electrical interconnects in nanoscale electronics. A key element in using CNT as electrical interconnects is the full understanding of the mechanical and electrical behavior of the interface between the CNT and copper (Cu) pad. The objective of this paper is to study the electronic structure and the electrical contact resistance at the interface between the open end of a single wall CNT and a Cu pad. To accomplish this, simulation cell consisting of an open-end single wall CNT with each end connected to a Cu electrode was created. The Cu/CNT/Cu system is fully relaxed first before a potential bias is prescribed between the Cu electrodes. The first-principle quantum mechanical density functional and non-equilibrium Green’s function (NEGF) approaches are adopted to compute the transport coefficient, while the current-voltage (I-V) relation is then extracted by invoking the Landauer-Buttiker formalism. The average density of state (DOS) and local density of states (LDOS) are also calculated to obtain the electron energy distribution around Fermi level point. Our simulation results show that electrons are conducted through the Cu/CNT/Cu system. In the low voltage bias regime (0.0∼0.1 V), I-V relationship is found to be linear. At higher voltage (> 2.0 V), the I-V relationship is nonlinear. Our results also show that the electrical contact resistance at the CNT/Cu interface is ∼3.6 kΩ at 0.1 V, and ∼4.8 kΩ at 2.0 V. These results indicate that for open-end CNTs, the contact resistance at the CNT/Cu interface is at least comparable to that of solder/Cu interface.

Optimisation of electrical contact resistance in Bi0.5Sb1.5Te3 for development of thermoelectric generators

2017 ◽  
Author(s):  
Ranu Bhatt ◽  
Anil K. Bohra ◽  
Shovit Bhattacharya ◽  
Ranita Basu ◽  
Sajid Ahmad ◽  
...  
Keyword(s):  
Contact Resistance ◽  
Electrical Contact ◽  
Thermoelectric Generators ◽  
Electrical Contact Resistance

Electrical Contact Resistance at the Carbon Nanotube/Pd and Carbon Nanotube/Al Interfaces in End-Contact by First-Principles Calculations

2011 ◽  
Vol 133 (2) ◽  
Author(s):  
Feng Gao ◽  
Jianmin Qu ◽  
Matthew Yao
Keyword(s):  
Electronic Structure ◽  
Carbon Nanotube ◽  
Contact Resistance ◽  
Density Functional ◽  
Electrical Contact ◽  
Electrical Contact Resistance ◽  
Functional Theory ◽  
Single Walled Carbon Nanotube ◽  
Current Voltage ◽  
Current Voltage Relation

Reported in this paper is a quantum mechanics study on the electronic structure and contact resistance at the interfaces formed when an open-end single-walled carbon nanotube (CNT) is in end-contact with aluminum (Al) and palladium (Pd), respectively. The electronic structures are computed using a density functional theory (DFT), and the transmission coefficient is calculated using a nonequilibrium Green’s function (NEGF) in conjunction with the DFT. The current–voltage relation of the simulating cell is obtained by using the Landauer–Buttiker formula, from which the contact resistance can be determined. Our results show that the electronic structure and electron transport behavior are strongly dependent on the electrode. It is found that the CNT/Pd interface has a weaker bond than the CNT/Al interface. However, the CNT/Pd interface shows a lower electrical contact resistance.

Electronic Structure of O-vacancy in High-k Dielectrics and Oxide Semiconductors

2011 ◽  
Vol 1370 ◽  
Author(s):  
Kee Joo Chang ◽  
Byungki Ryu ◽  
Hyeon-Kyun Noh ◽  
Junhyeok Bang ◽  
Eun-Ae Choi
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Device Performance ◽  
Oxide Semiconductors ◽  
Vacancy Defects ◽  
High K ◽  
Quasiparticle Energy ◽  
O Vacancy ◽  
Hybrid Density Functional

ABSTRACTFirst-principles density functional calculations are performed to investigate the electronic properties of O-vacancy defects in high-k HfO2, Si/HfO2 interface, and amorphous oxide semiconductors. The role of O-vacancy in device performance is discussed by comparing the results of the GGA, hybrid density functional, and quasiparticle energy calculations.

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