Control of Valence States by a Codoping Method in P-Type GaN Materials

1997 ◽  
Vol 468 ◽  
Author(s):  
T. Yamamoto ◽  
H. Katayama-Yoshtoa
Keyword(s):  
Control Method ◽  
Electronic Band Structure ◽  
Ionic Charge ◽  
Electronic Band ◽  
Valence States ◽  
Madelung Energy ◽  
Valence Control ◽  
P Type ◽  
Structure Calculations ◽  
Codoping Method

ABSTRACTWe propose a new valence control method, the “codoping method (using both n- and p-type dopants at the same time)”, for the fabrication of low-resistivity p-type GaN crystals based on the ab-initio electronic band structure calculations. We have clarified that while doping of acceptor dopants, BeGa and MgGa, leads to destabilization of the ionic charge distributions in p-type GaN crystals, doping of Sica or ON give rise to p-type doped GaN with high doping levels due to a large decrease in the Madelung energy. The codoping of the n- and p-type dopants (the ratio of their concentrations is 1:2) leads to stabilization of the ionic charge distribution inp-type GaN crystals due to a decrease in the Madelung energy, to result in an increase in the net carrier densities.

Role of n-Type Codopants on Enhancing p-Type Dopants Incorporation in p-Type Codoped Znse

1998 ◽  
Vol 510 ◽  
Author(s):  
T. Yamamoto ◽  
H. Katayama-Yoshida
Keyword(s):  
Nearest Neighbor ◽  
Electronic Band Structure ◽  
Hole Mobility ◽  
Ionic Charge ◽  
Electronic Band ◽  
Madelung Energy ◽  
P Type ◽  
Structure Calculations ◽  
High Donor

AbstractWe propose materials design for the fabrication of low-resistivity p-type ZnSe crystals using a new doping method which involves simultaneous codoping of both n- and p-type dopants, based on the ab initio electronic band structure calculations. We have clarified that while doping of acceptor dopants, Lizn and Nse, leads to the destabilization of the ionic charge distributions in p-type ZnSe crystals, doping of donor dopants, Inzn, ClSe or ISe gives rise to n-type doped ZnSe with high donor concentration due to a large decrease in the Madelung energy. The codoping of the n- and p-type dopants (the ratio of their concentrations is 1:2) enhances the incorporation of the acceptors in p-type ZnSe crystals due to a decrease in the Madelung energy, resulting in the formation of the p-n-p complexes which occupy nearest-neighbor sites. It results in an increase in the net carrier densities and the hole mobility due to a change in the scattering mechanism from that caused by long-range Coulomb scatters to that by short-range dipole-like ones

Electronic Structures of P-Type Doped CuInS2

1996 ◽  
Vol 426 ◽  
Author(s):  
T. Yamamoto ◽  
H. Katayama-Yoshida
Keyword(s):  
Electronic Structures ◽  
Electronic Band Structure ◽  
Spherical Wave ◽  
Material Design ◽  
Electronic Band ◽  
Design Considerations ◽  
Band Structure Calculations ◽  
P Type ◽  
Structure Calculations ◽  
Codoping Method

AbstractWe have studied the electronic structures of CuIn(S0.875X0.125)2 (X=B, C, N, Si or P) based on the ab-initio electronic band structure calculations using the augmented spherical wave (ASW) method. We have clarified that the physical characteristics of the p-type doped CuInS2 crystals are mainly determined by a change in the strength of interactions between Cu and S atoms. On the basis of the calculated results, we discussed the material design considerations, such as controlling the strength of resistivity for p-type doped CulnS2 materials and converting the conduction type, from n-type to p-type by a codoping method.

Control of Valence States in ZnO by CoDoping Method

2000 ◽  
Vol 623 ◽  
Author(s):  
T. Yamamoto ◽  
H. -K. Yoshida
Keyword(s):  
Electronic Band Structure ◽  
Repulsive Interaction ◽  
Promising Candidate ◽  
Electronic Band ◽  
Low Resistivity ◽  
Band Structure Calculations ◽  
Valence States ◽  
Madelung Energy ◽  
Doped Zno ◽  
Structure Calculations

AbstractWe have investigated the electronic structures of p- or n-type doped ZnO based on ab initio electronic band structure calculations in order to control valence states in ZnO for the fabrication of low-resistivity p-type ZnO. We find unipolarity in ZnO; p-type doping using Li or N increases the Madelung energy while n-type doping using Al, Ga, In or F species decreases the Madelung energy. We have proposed materials design: codoping using N acceptors and reactive codopants, Al or Ga, enhances electric properties in p-type codoped ZnO. It has been already verified by experiments using the N acceptors and Ga reactive donor codopants. We find a very weak repulsive interaction between Li acceptors and the delocalization of the Li-impurity states for Lidoped ZnO, in contrast with the case of N-doped ZnO. On the other hand, we find the compensation mechanism by the formation of 0 vacancy in the vicinity of the Li-acceptor sites. We propose a group VII element, F species, as a promising candidate for use of the reactive codopant as for Li-doped ZnO in order to realize low-resistivity p-type ZnO.

Control of Valence States for Zno And Zns with a Wide-Band Gap by a Codoping Method

2002 ◽  
Vol 719 ◽  
Author(s):  
T. Yamamoto
Keyword(s):  
Electronic Band Structure ◽  
Wide Band ◽  
Electrostatic Energy ◽  
Wide Band Gap ◽  
Electronic Band ◽  
Valence States ◽  
N Doping ◽  
Impurity Bands ◽  
Doped Zno ◽  
Codoping Method

AbstractWe have investigated the electronic structures of p- or n-type doped ZnO and ZnS based on the basis of the analysis of the results obtained by ab initio electronic band structure calculations. We find the doping problems of the two materials. They at highly N-doping levels have the narrow impurity bands at the top of the valence band, where holes are very localized by repulsion effects. As a solution to the doping problems described above, we proposed a codoping method: The deliberate codoping of the donors with N acceptors is essential for the enhancement of N-acceptor incorporation and delocalization of the N-impurity states with the electrostatic energy gain in p-type highly doped ZnO and ZnS.

scholarly journals Analyzing transport properties of p-type Mg2Si–Mg2Sn solid solutions: optimization of thermoelectric performance and insight into the electronic band structure

2019 ◽  
Vol 7 (3) ◽  
pp. 1045-1054 ◽  
Author(s):  
Hasbuna Kamila ◽  
Prashant Sahu ◽  
Aryan Sankhla ◽  
Mohammad Yasseri ◽  
Hoang-Ngan Pham ◽  
...  
Keyword(s):  
Band Structure ◽  
Transport Properties ◽  
Carrier Concentration ◽  
Solid Solutions ◽  
Figure Of Merit ◽  
Electronic Band Structure ◽  
Thermoelectric Performance ◽  
Electronic Band ◽  
P Type ◽  
Insight Into

Figure of merit zT mapping of p-Mg2Si1−xSnx with respect to carrier concentration.

Efficient Discovery of Optimal N-Layered TMDC Hetero-Structures

MRS Advances ◽  
2018 ◽  
Vol 3 (6-7) ◽  
pp. 397-402 ◽  
Author(s):  
Lindsay Bassman ◽  
Pankaj Rajak ◽  
Rajiv K. Kalia ◽  
Aiichiro Nakano ◽  
Fei Sha ◽  
...  
Keyword(s):  
Band Structure ◽  
Physical Properties ◽  
Band Gap ◽  
Electronic Band Structure ◽  
Transport Coefficients ◽  
Optimization Technique ◽  
Bayesian Optimization ◽  
Material Structure ◽  
Electronic Band ◽  
Structure Calculations

ABSTRACTVertical hetero-structures made from stacked monolayers of transition metal dichalcogenides (TMDC) are promising candidates for next-generation optoelectronic and thermoelectric devices. Identification of optimal layered materials for these applications requires the calculation of several physical properties, including electronic band structure and thermal transport coefficients. However, exhaustive screening of the material structure space using ab initio calculations is currently outside the bounds of existing computational resources. Furthermore, the functional form of how the physical properties relate to the structure is unknown, making gradient-based optimization unsuitable. Here, we present a model based on the Bayesian optimization technique to optimize layered TMDC hetero-structures, performing a minimal number of structure calculations. We use the electronic band gap and thermoelectric figure of merit as representative physical properties for optimization. The electronic band structure calculations were performed within the Materials Project framework, while thermoelectric properties were computed with BoltzTraP. With high probability, the Bayesian optimization process is able to discover the optimal hetero-structure after evaluation of only ∼20% of all possible 3-layered structures. In addition, we have used a Gaussian regression model to predict not only the band gap but also the valence band maximum and conduction band minimum energies as a function of the momentum.

Ab Initio Electronic Structure Studies of CuO Multiferroics

2012 ◽  
Vol 488-489 ◽  
pp. 129-132 ◽  
Author(s):  
C. Kanagaraj ◽  
Baskaran Natesan
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Metallic State ◽  
Magnetic Ground State ◽  
Electronic Band ◽  
Functional Theory ◽  
High Tc ◽  
Band Structure Calculations ◽  
Structure Calculations

We have performed detailed structural, electronic and magnetic properties of high - TC multiferroic CuO using first principles density functional theory. The total energy results revealed that AFM is the most stable magnetic ground state of CuO. The DOS and electronic band structure calculations show that in the absence of on-site Coulomb interaction (U), AFM structure of CuO heads to a metallic state. However, upon incorporating U in the calculations, a band gap of 1.2 eV is recovered. Furthermore, the Born effective charges calculated on Cu does not show any anomalous character.This suggests that the polarization seen in CuO could be attributed to the spin induced AFM ordering effect.

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