scholarly journals First principles simulations of microscopic mechanisms responsible of the drastic reduction of electrical deactivation defects in Se hyperdoped silicon

Author(s):  
Alberto Debernardi

By first principles simulations we systematically investigate Se hyperdoped silicon by computing, for different types of Se complexes, the formation energy as a function of dopant concentration. We identify the...

2013 ◽  
Vol 307 ◽  
pp. 387-390
Author(s):  
Jian Xin Zhu ◽  
Da Wei Jin ◽  
Jian Zhang ◽  
Hong Liang Zhao

NiTi shape memory alloy is considered to be the most important shape memory alloys for its salient superelasticity and shape memory effect,which are displayed in martensitic transformations.In this paper, first-principles plane-wave method is utilized to systemically investigate the geometrical and electronic structures of NiTi (100) surface.Calculated the adsorption of oxygen atoms on the Ti/ NITI different location .The formation energy, Millikan population analysis results show that the Oxygen atoms easy to be adsorbed on the surface of Ti end surface,formation of TiO2.


Crystals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 48 ◽  
Author(s):  
Qing Peng ◽  
Nanjun Chen ◽  
Danhong Huang ◽  
Eric Heller ◽  
David Cardimona ◽  
...  

Point defects are inevitable, at least due to thermodynamics, and essential for engineering semiconductors. Herein, we investigate the formation and electronic structures of fifteen different kinds of intrinsic point defects of zinc blende indium arsenide (zb-InAs ) using first-principles calculations. For As-rich environment, substitutional point defects are the primary intrinsic point defects in zb-InAs until the n-type doping region with Fermi level above 0.32 eV is reached, where the dominant intrinsic point defects are changed to In vacancies. For In-rich environment, In tetrahedral interstitial has the lowest formation energy till n-type doped region with Fermi level 0.24 eV where substitutional point defects In A s take over. The dumbbell interstitials prefer < 110 > configurations. For tetrahedral interstitials, In atoms prefer 4-As tetrahedral site for both As-rich and In-rich environments until the Fermi level goes above 0.26 eV in n-type doped region, where In atoms acquire the same formation energy at both tetrahedral sites and the same charge state. This implies a fast diffusion along the t − T − t path among the tetrahedral sites for In atoms. The In vacancies V I n decrease quickly and monotonically with increasing Fermi level and has a q = − 3 e charge state at the same time. The most popular vacancy-type defect is V I n in an As-rich environment, but switches to V A s in an In-rich environment at light p-doped region when Fermi level below 0.2 eV. This study sheds light on the relative stabilities of these intrinsic point defects, their concentrations and possible diffusions, which is expected useful in defect-engineering zb-InAs based semiconductors, as well as the material design for radiation-tolerant electronics.


2021 ◽  
Vol 245 ◽  
pp. 03003
Author(s):  
Zhaowen Huang ◽  
Benjing Chen ◽  
Jingyang Li ◽  
Lingzhi Zhao

In this paper, based on the first principle method, the mechanism of lithium intercalation and deintercalation of P-Cu alloy as anode material of lithium-ion battery was studied. The results followed that the volume expansion coefficient of Li-P-Cu is small, 59.4650% for Li2PCu3 and 61.4071% for Li2P2Cu, indicating that the introduction of Cu can effectively inhibit the volume expansion of phosphorus. And PCu3 is superior to P2Cu in terms of volume expansion coefficient and lithium intercalation formation energy and good conductivity.


RSC Advances ◽  
2019 ◽  
Vol 9 (59) ◽  
pp. 34158-34165 ◽  
Author(s):  
N. Raja ◽  
D. Murali ◽  
S. V. M. Satyanarayana ◽  
M. Posselt

The temperature dependence of the free formation energy of Ba, Zr and O vacancies in BaZrO3 is investigated for all possible charge states and atomic reservoir conditions.


2012 ◽  
Vol 26 (27) ◽  
pp. 1250179 ◽  
Author(s):  
QINGYU HOU ◽  
YONGJUN JIN ◽  
CHUN YING ◽  
ERJUN ZHAO ◽  
YUE ZHANG ◽  
...  

Anatase TiO 2 supercells were studied by first-principles, in which one was undoped and another three were high N -doping. Partial densities of states, band structure, population and absorption spectrum were calculated. The calculated results indicated that in the condition of TiO 2-x N x (x = 0.0625, 0.125, 0.25), the higher the doping concentration is, the shorter will be the lattice parameters parallel to the direction of c-axis. The strength of covalent bond significantly varied. The formation energy increases at first, and then decreases. The doping models become less stable as N -doping concentration increases. Meanwhile, the narrower the band gap is, the more significant will be the redshift, which is in agreement with the experimental results.


2016 ◽  
Vol 30 (30) ◽  
pp. 1650217 ◽  
Author(s):  
Sihao Xia ◽  
Lei Liu ◽  
Yike Kong ◽  
Honggang Wang ◽  
Meishan Wang

In order to investigate the influences of different Al constituents on Ga[Formula: see text]Al[Formula: see text]N nanowires, the formation energy, stability, band structure, densities of states and optical properties of Ga[Formula: see text]Al[Formula: see text]N nanowires with different Al constituents are calculated using first-principles plane-wave ultrasoft pseudopotential method. Results show that Ga[Formula: see text]Al[Formula: see text]N nanowires become more stable with increasing Al constituent. Bandgap of Ga[Formula: see text]Al[Formula: see text]N nanowires increases as the Al constituent increases but with a lower amplification compared with bulk Ga[Formula: see text]Al[Formula: see text]N. The peaks of static dielectric constants show a decreasing trend and move towards high-energy side as Al constituent increases. The absorption of Ga[Formula: see text]Al[Formula: see text]N nanowires shows an interesting phenomenon that it firstly increases and then decreases slightly as the Al constituent increases. Reflectivity of Ga[Formula: see text]Al[Formula: see text]N nanowires is much smaller than that of the bulk. The optical properties of Ga[Formula: see text]Al[Formula: see text]N nanowires show a blueshift effect as Al composition increases. According to these calculations, it is found that Ga[Formula: see text]Al[Formula: see text]N nanowires are appropriate to be applied into photoelectric detecting materials by adjusting the Al constituent of Ga[Formula: see text]Al[Formula: see text]N nanowires.


2018 ◽  
Vol 32 (14) ◽  
pp. 1850178 ◽  
Author(s):  
Xuefeng Lu ◽  
Xu Gao ◽  
Junqiang Ren ◽  
Cuixia Li ◽  
Xin Guo ◽  
...  

Bandgap tailoring of [Formula: see text]-Si3N4 is performed by single and co-doping by using density functional theory (DFT) of PBE functional and plane-wave pseudopotential method. The results reveal that a direct bandgap transfers into an indirect one when single-doped with As element. Also, a considerate decrease of bandgap to 0.221 eV and 0.315 eV is present for Al–P and As–P co-doped systems, respectively, exhibiting a representative semiconductor property that is characteristic for a narrower bandgap. Compared with other doped systems, Al-doped system with formation energy of 2.67 eV is present for a more stable structure. From charge density difference (CDD) maps, it is found that the blue area between co-doped atoms increases, illustrating an enhancement of covalent property for Al–P and Al–As bonds. Moreover, a slightly obvious “Blue shift” phenomenon can be obtained in Al, Al–P and Al–As doped systems, indicating an enhanced capacity of responses to light, which contributes to the insight for broader applications with regard to photoelectric devices.


2015 ◽  
Vol 17 (7) ◽  
pp. 5485-5489 ◽  
Author(s):  
M. N. Amini ◽  
R. Saniz ◽  
D. Lamoen ◽  
B. Partoens

With the help of first-principles calculations, we investigate the VZn–NO–H acceptor complex in ZnO. We find that H plays an important role, because it lowers the formation energy of the complex with respect to VZn–NO, a complex known to exhibit p-type behavior. However, this additional H atom also occupies the hole level of VZn–NO making the VZn–NO–H complex a deep acceptor.


2013 ◽  
Vol 2013 ◽  
pp. 1-4 ◽  
Author(s):  
Deng-Feng Li ◽  
Min Luo ◽  
Bo-Lin Li ◽  
Cheng-Bing Wu ◽  
Bo Deng ◽  
...  

By using first principles calculations, we propose a codoping method of using acceptors and donors simultaneously to realize low-resistivity and high carrier concentration p-type ZnS with wurtzite structure. The ionization energy of singleNScan be lowered by introducing theIIIZn-NS(III = Al, Ga, In) passivation system. Codoping method in ZnS (2N, III) has lower formation energy comparing with single doping of N since III elements act as reactive codopants.


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