Ternary Chalcopyrite Semiconductors Research Articles

Structural, elastic, electronic, optical and thermoelectric properties of metal based ternary chalcopyrite semiconductor for photovoltaic application: First-principles studies

In this article, the physical properties of XCrS2 (X = Zn, Cd, and Hg) are studied by Density Functional Theory (DFT) using Wien2K code. Stability, along with certain parameters of the crystal structures of the compounds, was evaluated based on PBE-GGA. Mechanical properties reveal that the studied compounds XCrS2 (X = Zn, Cd) are stable, and their elastic constants and Paugh’s ratio exhibit that ZnCrS2 is brittle, whereas CdCrS2 is ductile in nature. Furthermore, HgCrS2 does not satisfy the Born stability criteria. The modified Becke-Johnson (mBJ) potential was used to improve the band gap properties and results depict that the XCrS2 (X = Zn, Cd) compounds have 1.30 and 1.27 eV direct band gaps, respectively. Thermoelectric properties exhibit the highest optical conductivity with energy loss and the strongest absorption is observed for CdCrS2 in the visible region, which also has the best photovoltaic activity. The higher obsorption nature makes this material a good candidate for solar devices. The electrical and thermal conductivity increase with an increase in temperature, and ZnCrS2 has a greater ZT compared to CdCrS2.

Effects of pressure on structural, mechanical, and electronic properties of chalcopyrite compound CuAlS2

First-principles method is performed to investigate the structural, electronic, elastic and mechanical characteristics of the tetragonal CuAlS2 in the pressure range from 0 to 10 GPa. The results indicated that both the lattice constant and cell volume decrease with the increase of pressure, which are matched well with available previous values. The pressure has a more significant influence on the c direction than the a and b direction. The obtained elastic constants reveal the tetragonal CuAlS2 is mechanically stable between 0 and 10 GPa. The bulk, shear, and Young’s modulus are evaluated by Voigt-Reuss-Hill approximation. All these elastic moduli exhibit a monotonic feature as a function of pressure. The Poisson’s ratio, Pugh’s criterion, and Cauchy pressure indicate that ternary chalcopyrite semiconductor CuAlS2 is ductile against pressure. Meanwhile, the analysis of the electronic structures reveals that the states near the valence band top are derived from Cu 3d and S 3p orbitals, and the lowest conduction band is composed of Al 3p and S 3p orbitals. We expect that the findings predicted the physical properties of this compound will promote future experimental studies on CuAlS2.

Size-dependent radiative recombination characteristics of isolated CuInS2 nanocrystals

Ternary chalcopyrite semiconductor nanocrystals of the I–III–VI2 type are potential nontoxic alternatives to Cd- and Pb-based chalcogenide nanocrystals, which can be adopted for light emission and photovoltaic applications. Most I–III–VI2 nanocrystals exhibit luminescence originated from defect-related recombination, which is characterized by a broad spectrum with a large Stokes shift regardless of the size-dependent spectral shift due to the quantum size effect. However, the origin of the luminescence in I–III–VI2 nanocrystals is still under debate, and deeper investigations of the carrier recombination processes are necessary to gain further understanding of the luminescence mechanisms. For this purpose, we investigated the temperature dependence of the luminescence properties of CuInS2 nanocrystals down to cryogenic temperatures to suppress the nonradiative recombination. The intrinsic luminescence properties of the isolated CuInS2 nanocrystals were successfully evaluated by eliminating the influence of the interactions among the nanocrystals, which is different from previous studies on nanocrystal aggregates. Both the thermal quenching behavior and the temperature dependence of the carrier recombination rate could be satisfactorily described using a simple model that assumes a thermally activated nonradiative recombination. The radiative recombination rates of the CuInS2 nanocrystals were found to be 106–107 s−1, and a characteristic cubic dependence of the radiative recombination rate on the nanocrystal diameter was found.

Significant Improvement in Thermoelectric Performance of AgInSe2-Based Composites through In Situ Formation of Ag2Se

As the development of n-type ternary chalcopyrite semiconductors in thermoelectrics (TEs) is relatively slow compared to that of their p-type counterparts, it greatly restricts the fabrication of t...

On the effect of structural disorders on the Urbach’s tails of ternary chalcopyrite semiconductors and related ordered defect compounds

The effect of structural disorders on the Urbach's tails (UTs) in the optical absorption spectra in CuBIIIC2VI, CdBIVC2V ternary chalcopyrite semiconductors and other related CuB3IIIC5VI, CuB5IIIC8VI, and Cu3B5IIIC9VI ordered defect compounds (ODCs) is studied. Analysis of UT in such a large number of ternary compounds with the adjustable parameters P and N permits us to have a better understanding of their physical importance. These parameters are used to explain the variation of Urbach’s energy EU with temperature T. They take into account the basic effect of substitutional disorder caused by molecularity and deviation from stoichiometry and also the handicap in the thermal weight due to the distribution of the resulting additional phonon modes, respectively. They play an important role in determining quantitatively the presence of structural defects. P explains quite well higher values of hνp observed in multinary compounds, and N indicates when an order–disorder phase transition could occur in these materials. It is also found that the energy of phonons involved in the formation of the photon absorption edge hνp in ODCs is higher than that observed in normal CuBIIIC2VI chalcopyrite compounds and increases linearly as the effective cation radius reff increases in the sequence CuB5IIIC8VI→CuB3IIIC5VI→Cu3B5IIIC9VI. The analysis also suggests that the magnitude of these parameters can be very useful in device applications of these materials such as solar cells and thermoelectric power generation.

Low temperature electrical impedance spectroscopy characterization of n type CuInSe2 semiconductor compound

In this report, the ternary chalcopyrite semiconductor n-CulnSe2 (n-CIS112) was studied using impedance spectroscopy (IS) over a wide range of temperatures [80 K, 300 K] and frequencies [20 Hz, 1 MHz]. The ingot was grown by vertical Bridgman technique. The experimental data are analyzed to estimate the activation and relaxation energies. The activation energies agree with those reported from Hall effect measurements. The predominance of both “bulk” and “grain-boundary” contributions to the electrical conduction is confirmed by using impedance and modulus formalism. AC electrical conductivity data σac(ω,T) for n-CulnSe2 are discussed using the theoretical Overlapping Large Polaron Tunneling process.

Characterization of CBD deposited CuInSe2 thin film

Ternary CuInSe2 chalcopyrite semiconductor thin films have been deposited on glass slide substrates by chemical bath deposition technique. The chemical composition of the as-deposited thin film by energy dispersive analysis of X-ray technique showed the film to be near stoichiometric. The X-ray diffraction analysis of the thin film confirmed the tetragonal unit cell structure. All the obtained lattice parameters were in good agreement with the reported data. The crystallite size determined by Scherrer's formula and Hall-Williamsons relation using X-ray diffraction data were in good agreement with each other. The microtopograph study of the as-deposited thin film surfaces by optical and scanning electron microscopy showed that the thin film uniformly covers the entire substrate surface. The atomic force microscopy of the thin film surface showed grains and coalescence between them. The as-deposited thin film possesses direct optical bandgap having value of 1.39eV being analyzed by Ultra violet-Visible-Near infra red spectroscopy. The optical parameters like reflectance R, transmittance T variation with wavelength and extinction coefficient k, dielectric constant εc and refractive index η variation with incident photons hν showed the as-deposited thin film can be used as an absorber in the visible region of spectrum. The electrical transport properties study confirmed the semiconducting and p-type nature of the as-deposited thin film. The obtained results are comprehensively discussed in this paper.

Determination of the basic physical properties of semiconductor chalcopyrite type MgSnT2 (T = P, As, Sb) from first-principles calculations

Abstract

Ab initio study of structural, electronic and optical properties of ternary chalcopyrite semiconductors

In this paper, structural, electrical and optical properties of AgGaX2 (X=S, Se, Te) were studied by using Full Potential Linear Augmented Plane Wave (FP-LAPW) based on density functional theory. Perdew Becke Ernzerhof (GGA-PBE) and Wu Cohen Generalized gradient approximation (GGA-Wc), Engel Voskov Generalized Gradient Approximation (EV) and modified Becke-Johnson exchange potential (MBJ) were used for the exchange correlation potential. GGA-PBE was closed to the other and experimental data for lattice constant, bulk modulus (B) and its first derivative (B′), and MBJ potential was in good agreement with the experiment and other calculations for band gap energy and the optical properties. Band structure, total and partial density of states were plotted to obtain electronic properties and the band gap was direct for all components. By using imaginary and real part of dielectric functions, some optical properties such as reflection coefficient (R), refractive index (n), extinction coefficient (k) were obtained and the role of X atoms (X=S, Se, Te) in optical properties were investigated.

The first-principles study of electrical and thermoelectric properties of CuGaTe2 and CuInTe2

The thermoelectric material is a kind of new functional material, which can convert industrial waste heat and automobile exhaust into the available electric energy by the interaction of carriers. It is widely used in energy, environment, national defense and other fields. For the research of thermoelectric materials, it is the most important to improve the conversion efficiency now. Due to their unique structural properties, the ternary chalcopyrite semiconductors I-III-IV2 (I=Ag, Cu; III=Al, Ga, In; IV=S, Se, Te) display the better thermoelectric performances at high temperature. Many studies show that there are many ways to improve their performances. In order to optimize their thermoelectric efficiencies the structural, elastic and thermoelectric properties of CuGaTe2 and CuInTe2 are studied by employing the density function theory and semi-classical Boltzmann transport theory within the constant time approximation. The electronic band structures are calculated using the Tran-Blaha modified Becke-Johnson potential (MBJ-GGA) and the generalized gradient approximation (GGA). The calculated band gaps with MBJ-GGA of CuGaTe2and CuInTe2 are 0.86 and 0.56 eV, which are more accurate than the calculated values with GGA. The shear modulus, and Young's modulus and sound velocities are determined from the obtained elastic constants. The constant-volume heat capacity is estimated based on the quasi-harmonic Debye model. The calculated temperature dependence of heat capacity agrees very well with the experimental result. Below room temperature, the heat capacity increases quickly with the increasing of temperature. Above room temperature, the heat capacity approaches to the Dulong-Petit limit. In paper, we assume that the lattice thermal conductivities of CuGaTe2 and CuInTe2 are mainly from the phonon scattering. And the phonon scattering is dominated by Umklapp scattering. The calculated lattice thermal conductivities can fit the form kl = A/T-Bin the temperature range of 300-800 K. For CuGaTe2, A = 2869.96 and B = 2.86. The fitting result well approaches to the experimental values and other theoretical results. Based on the calculated band structures with mBJ-GGA potential, the transport properties of CuGaTe2 and CuInTe2 each as a function of chemical potential at various temperatures are investigated. The values of Seebeck coefficient S first increase and then decrease for n-type and p-type doping at low carrier concentrations, which are consistent with the previous results. Electrical conductivity divided by scattering time, i.e. / increases monotonically with chemical potential increasing. The power factor divided by scattering time, i.e. S2/ first increases and then decreases with chemical potential increasing. The magnitude of S2/ increases with temperature increasing. Besides, it is found that the value of S2/ for p-type doping is larger than that for n-type doping. These results show that optimizing the carrier concentration can improve their thermoelectric performances. In order to calculate the electrical conductivity, in this paper we estimate the scattering time from the experiments of Ref.[3]. The CuGaTe2 at 700 K possesses a figure of merit 0.63. These calculated results show that CuGaTe2 and CuInTe2 both are good thermoelectric materials with p-type doping.

Refractive Index and Electronic Polarizability of Ternary Chalcopyrite Semiconductors

Simple models are proposed for the calculation of refractive index n and electronic polarizability α of AI BIII C2VI and AII BIV C2V groups of chalcopyrite semiconductors from their energy gap data. The values of n and α for 2 compounds of AI BIII C2VI family and 12 compounds of AII BIV C2V family are calculated for the first time in this work. The proposed models are applicable for the whole range of energy gap materials. The calculated values are compared with the available experimental and reported values. A fairly good agreement between them is obtained.

Nanorod Formation of Copper Indium (di) Selenide Nanorod Synthesize by Solvothermal Route

The compound belongs to I-III-VI2 group are promising material as an effective light-absorbing materials. Now a day, ternary chalcopyrite semiconductors, especially copper based I-III-VI2 semiconductors have attracted many investigators. They have several desirable features as absorbers in the thin film solar cells. In present work, copper indium (di) selenide have been prepared via solvothermal route. Several methods have been reported to prepare CuInSe2 nanostructures by solution route. In present work, tetragonal chalcopyrite copper indium (di) selenide nanorods has been synthesized by solvothermal method using ethylene diamine as a solvent. Structural analysis had been done by X-ray diffraction (XRD). The surface morphology of the as-grown nanorod has been studied using scanning electron microscopy. The bandgap of as grown nanorods is obtained from UV-Vis spectrum which will applicable to the solar cell devices.

Linear properties of ternary chalcopyrite semiconductors

Linear properties of ternary chalcopyrite semiconductors have been studied. New relations based on plasma oscillations theory of solids have been proposed for calculation of homopolar, heteropolar and average energy gaps, dielectric constant and ionicity of A–C and B–C bonds in AIBIIIC2VI and AIIBIVC2V groups of semiconductors. The values of these parameters for 13 new chalcopyrites of AIIBIVC2V family have been calculated. The calculated values are compared with the available reported values and a fairly good agreement has been obtained.

Fabrication of Cu3Zn3Se ternary compounds by AP-MOCVD

I–II–VI Ternary chalcopyrite semiconductors of Cu1−xZn1−ySe2−δ (Cu3Zn3Se) were successfully fabricated by the atmospheric pressure metal-organic chemical vapor deposition method for the first time. Four major peaks of (112), (220)/(204), (312)/(116), and (400), accompanied by three minor peaks of (103), (211) and (301) were observable in the X-ray diffraction spectra. In particular, the presence of those latter low-intensity peaks featured the formation of the chalcopyrite type Cu3Zn3Se compound. Typical absorption coefficients of the films produced were found to vary from 2.75×104cm−1 to 5.75×104cm−1 over all visible light range and from the same optical absorption spectra the energy gap of the material was extracted to be about 2.02eV. Moreover, the photoluminescence measurement conducted at room temperature also exhibited a strong orange-colored emission line at 1.94eV, which further confirmed that the Cu3Zn3Se ternary compound has been prepared. In addition, the cross-sectional and top-view scanning electron microscopy images characterized the fabricated Cu3Zn3Se compound as a polycrystalline film of thickness about 1–1.3μm and consisting of 1–2.5μm sized grains.

Correlation between ground state properties and plasmon energy of ternary chalcopyrite semiconductors.

Correlation between ground state properties and plasmon energy of ternary chalcopyrite semiconductors.

Second order nonlinear optical properties of AIBIIIC2VI chalcopyrite semiconductors

The second-order nonlinear optical (NLO) properties of ternary chalcopyrite semiconductors have been studied. The NLO tensor coefficients (d36) of the A-C and B-C bonds in AIBIIIC2VI semiconductors and their total contribution to whole family of these compounds have been calculated at 10.6 μm using plasma oscillations theory of solids. The calculated values are compared with the experimental values and the values reported by different workers. Reasonably good agreement has been found between them.

BAND GAP ENGINEERING OF CRYSTAL MATERIALS: BAND GAP ESTIMATION OF SEMICONDUCTORS VIA ELECTRONEGATIVITY

We have developed empirical equations to quantitatively calculate the band gap values of binary ANB8-N and ternary ABC2 chalcopyrite semiconductors from the general viewpoint of chemical bonding processes upon electronegativity (EN). It is found that the band gap of crystal materials is essentially determined by the binding energy of chemical bonds to the bonding electrons, which can be effectively described by the average attractive abilities of two bonded atoms to their valence electrons and the delocalization degree of the valence electrons. The calculated band gap values of a large number of compounds can agree well with the available experimental data. This work provides us an efficient approach to quantitatively predict the band gap values of inorganic crystal materials on the basis of fundamental atom parameters such as EN, atomic radius, etc.

Optoelectronic properties of zinc blende and wurtzite structured binary solids

In this paper, we studied zinc blende (ZB) and wurtzite (Wu) type structured binary solids with conduction electrons and calculated the optoelectronic properties such as high frequency refractive index (n), optical susceptibility (χ), electronic polarizability (αe) and crystal ionicity (fi) using the plasma oscillation theory of solids formalism already employed for ternary chalcopyrite semiconductors. The present method is not limited to tetrahedrally coordinated semiconductors and ternary chalcopyrites, but can be used for all semiconducting compounds. We have applied extended formulae on zinc blende (ZB) and wurtzite (Wu) type structured binary semiconductors and found better agreement with the experimental data as compared to the values evaluated by previous researchers. The high frequency refractive index (n), optical susceptibility (χ), electronic polarizability (αe) and crystal ionicity (fi) of zinc blende (ZB) and wurtzite (Wu) type structure compounds exhibit a linear relationship when plotted on a log–log scale as against the plasmon energy N›ωp (in eV), which lies on a straight line. The results for high frequency refractive index differ from experimental values by the following amounts: ZnS (0%), ZnSe (0%), ZnTe (11%), CdS (11%), CdSe (15%), CdTe (20%), HgSe (5%), BN (20%), AlN (16%), AlP (15%), AlAs (0%), AlSb (13%), GaN (18%), GaP (27%), GaAs (8%), GaSb (7%), InN (8%), InP (5%), InAs (0.3%) and InSb (0.9%); and the results for optical susceptibility differ from experimental values by the following amounts: ZnS (10%), ZnSe (2%), ZnTe (8%), CdS (25%), CdSe (17%), CdTe (7%), AlAs (4.8%), AlSb (16%), GaP (1.6%), GaAs (9.8%), GaSb (22.7%), InP (12.8%), InAs (9%) and InSb (20%) in the present study. Key words: A. semiconductors, D. electronic properties, D. optical properties

Photoluminescence Compounds ZnGa<sub>2</sub>Se<sub>4</sub> and ZnGa<sub>2</sub>Se<sub>4</sub>: Eu<sup>2+</sup>

Photoluminescence (PL) spectra measurements have been carried out in the ternary chalcopyrite semiconductor compounds ZnGa2Se42Se4: Eu2+ using single-wavelength excitation of a Hg lamp with λ = 365 and 375 nm. Measurements were performed at the temperature range of (120 ~ 220 K) and (110 ~ 230 K) for ZnGa2Se4 and ZnGa2Se4:Eu2+, respectively. No PL was observed for both crystals at the temperatures higher than 220 K (ZnGa2Se4) and 230 K (ZnGa2Se4:Eu2+). At temperatures lower than ~220 K and ~230 K one and three lines were observed for ZnGa2Se4 and ZnGa2Se4: Eu at 591 nm and 566, 591, 646 nm, respectively. 566 nm line was assigned as due of the 4f65d→ 4f7 (8S7/2) transition of Eu2+ ions, whereas the rest two lines were attributed to the donor-acceptor recombination pairs. Probability of non-radiation transfers (A = 108 ~109 s-1), energy of optical phonons (hω= 25 ~ 30 meV), Huan Rice parameter (S = 8 ~ 10), energy of thermal quenching (△E = 0.02 ~ 0.06 eV) were determined from the tem-perature dependences of the full width at half maximum (FWHM = Г(T)).

Static and dynamical properties of II–VI and III–V group binary solids

In this paper, we extend to II–VI and III–V group binary solids of zinc blende (ZB) structure with conduction d-electrons the calculation of static and dynamical properties such as bulk modulus (B) and cohesive energy or total energy (Ecoh) using the plasma oscillation theory of solids formalism already employed for ternary chalcopyrite semiconductors. The present method is not limited to tetrahedrally coordinated semiconductors and ternary chalcopyrites, but can be used for all semiconducting compounds. We have applied an extended formula on ZB structured binary semiconductors and found better agreement with the experimental data as compared to the values evaluated by previous researchers. The bulk modulus and cohesive energy of ZB-type structure compounds exhibit a linear relationship when plotted on a log–log scale against the plasmon energy ℏωp (in eV), but fall on a straight line. The results for bulk modulus differ from experimental values by the following amounts: ZnS 0.36%, ZnSe 10%, ZnTe 0.62%, CdS 1.8%, CdSe 7.4% and CdTe 1.6%, AlP 2.6%, AlAs 5.3%, AlSb 4.0%, GaP 0%, AlAs 0%, AlS 4.4%, InP 0%, InAs 0% and InSb 2.1%; and the results for cohesive energy differ from experimental values by the following amounts: ZnS 0.16%, ZnSe 0.73%, ZnTe 0.6%, CdS 7.6%, CdSe 3.5%, CdTe 2.5%, AlP 2.0%, AlAs 3.0%, AlSb 11.1%, GaP 14.6%, AlAs 17.0%, AlSb 8.7%, InP 4.3%, InAs 5.5% and InSb 0.6%.