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Boltzmann equations and ab initio calculations: comparative study of cubic and wurtzite CdSe.

Abbassi A, Zarhri Z, Azahaf Ch, Ez-Zahraouy H, Benyoussef A - Springerplus (2015)

Bottom Line: With the mBJ approximation the gap found for cubic and wurtzite structure is direct and is equal to 1.85 and 1.7 eV respectively, what corresponds to the experiment results.The optical absorption is significant in the ultraviolet field while it becomes low beyond 600 nm in the visible light for CdSe in different structures.These results can be exploited in several applications of CdSe in optoelectronic devices.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Magnetism and High Energy Physics (URAC 12), Faculty of Sciences, Mohammed V University, B.P. 1014, Rabat, Morocco.

ABSTRACT
The electronic and optical properties of CdSe in two phases, cubic and wurtzite, have been studied by first principal calculations using the density functional theory. The optical parameters such as transmittance, optical absorption, refractive index and extinction coefficient have been investigated. We have calculated also the band structure, and total/partial density of state using the full potential-linearized augmented plane wave method with the local density approximation, generalized gradient approximation and the modified Becke-Johnson functional (mBJ), implemented in the Wien2k package. With the mBJ approximation the gap found for cubic and wurtzite structure is direct and is equal to 1.85 and 1.7 eV respectively, what corresponds to the experiment results. The optical absorption is significant in the ultraviolet field while it becomes low beyond 600 nm in the visible light for CdSe in different structures. From λ = 400 nm the transmittance is stable and reaches 80 %. With Boltztrap package, we have investigated also that with increasing temperature, the electrical conductivity increases. During the calculation, the cubic structure has presented an isotropy. While for wurtzite CdSe, the propagation of waves into system is different in xx and zz directions. These results can be exploited in several applications of CdSe in optoelectronic devices.

No MeSH data available.


CdSe structures, cubic and wurtzite
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Fig2: CdSe structures, cubic and wurtzite

Mentions: We have noted that both structures present DOS with presence of different regions of bands and energy levels. In the case of the cubic structure we observe that a very intense region appears in the conduction band and especially from 4.5 eV. The hexagonal structure as shown in Fig. 2, presents a region with a very intense energy levels in valence and the conduction band. We will make a detailed calculation in the total and partial density of states in order to understand this electronic structure. Fig. 1


Boltzmann equations and ab initio calculations: comparative study of cubic and wurtzite CdSe.

Abbassi A, Zarhri Z, Azahaf Ch, Ez-Zahraouy H, Benyoussef A - Springerplus (2015)

CdSe structures, cubic and wurtzite
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4580675&req=5

Fig2: CdSe structures, cubic and wurtzite
Mentions: We have noted that both structures present DOS with presence of different regions of bands and energy levels. In the case of the cubic structure we observe that a very intense region appears in the conduction band and especially from 4.5 eV. The hexagonal structure as shown in Fig. 2, presents a region with a very intense energy levels in valence and the conduction band. We will make a detailed calculation in the total and partial density of states in order to understand this electronic structure. Fig. 1

Bottom Line: With the mBJ approximation the gap found for cubic and wurtzite structure is direct and is equal to 1.85 and 1.7 eV respectively, what corresponds to the experiment results.The optical absorption is significant in the ultraviolet field while it becomes low beyond 600 nm in the visible light for CdSe in different structures.These results can be exploited in several applications of CdSe in optoelectronic devices.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Magnetism and High Energy Physics (URAC 12), Faculty of Sciences, Mohammed V University, B.P. 1014, Rabat, Morocco.

ABSTRACT
The electronic and optical properties of CdSe in two phases, cubic and wurtzite, have been studied by first principal calculations using the density functional theory. The optical parameters such as transmittance, optical absorption, refractive index and extinction coefficient have been investigated. We have calculated also the band structure, and total/partial density of state using the full potential-linearized augmented plane wave method with the local density approximation, generalized gradient approximation and the modified Becke-Johnson functional (mBJ), implemented in the Wien2k package. With the mBJ approximation the gap found for cubic and wurtzite structure is direct and is equal to 1.85 and 1.7 eV respectively, what corresponds to the experiment results. The optical absorption is significant in the ultraviolet field while it becomes low beyond 600 nm in the visible light for CdSe in different structures. From λ = 400 nm the transmittance is stable and reaches 80 %. With Boltztrap package, we have investigated also that with increasing temperature, the electrical conductivity increases. During the calculation, the cubic structure has presented an isotropy. While for wurtzite CdSe, the propagation of waves into system is different in xx and zz directions. These results can be exploited in several applications of CdSe in optoelectronic devices.

No MeSH data available.