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 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.

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.

Ab initio electronic band structure calculations of half-metallic c alcium pnictides

2007 ◽  
Vol 244 (12) ◽  
pp. 4643-4650 ◽  
Author(s):  
G. Jaiganesh ◽  
R. D. Eithiraj ◽  
G. Kalpana ◽  
M. Rajagopalan
Keyword(s):  
Band Structure ◽  
Ab Initio ◽  
Electronic Band Structure ◽  
Electronic Band ◽  
Half Metallic ◽  
Band Structure Calculations ◽  
Structure Calculations

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.

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