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Chalcogenide lone pair semiconducting materials are important materials due to their prospective applications in thermoelectrics, phase change memories, topological insulators etc. Investigating these lone pair semiconductors for versatile applications, different electronic properties were studied by researchers world-wide. Analyses of these semiconducting materials in bulk and thin films for electronic properties like dark and photo-conductivity, photosensitivity, carrier concentration, carrier type, relaxation time and thermopower are the major constituents while accepting them for applications. This review stresses on the electronic properties of several binary, ternary and quaternary lone pair chalcogenide systems. The electronic properties are generally discussed on the basis of chemical ordering in system. A brief discussion on some theoretical background of conduction mechanism has also been incorporated for new researchers in this field. Potential applications of chalcogenide semiconducting materials have been outlined.

Superparamagnetic nanoparticles have astounding applications in the field of biomedical. Co-precipitated Nd3+ doped Mn0.5Zn0.5NdxFe2−xO4, where x = 0, 0.025, 0.050, 0.075, 0.1 ferrite nanoparticles are examined utilizing various characterization methods at room temperature. XRD, FE-SEM and FTIR analysis reveal the origination of cubical spinel ferrite structure. A transition from paramagnetic to superparamagnetic nature has been observed with Nd3+ addition (x > 0.025). To comprehend the relationship of structural and magnetic properties a cation distribution has been proposed and found to be in agreement with experimental observations. Absorption spectra show a red shift with Nd3+ doping. PL spectra show a blue shift in band edge emission upto x = 0.050. The results obtained from UV–visible spectroscopy and PL spectroscopy show an anti-Stokes shift with Nd3+ doping owing to the photon upconversion process. The obtained magnetic results in fusion with optical results for ferrite nanoparticles are prospective in imaging and biomedical applications.

Te-based chalcogenide glasses own the most comprehensive infrared window among amorphous materials and have far-infrared applications such as CO2 detection. Nevertheless, the glass forming ability and thermal stability decrease for higher Te content chalcogenide glasses. Here, we report the effect of Ga addition on Te-based chalcogenide glasses by presuming that the addition of Ga may develop the configurational disorder and hence may improve the glass forming ability and thermal stability. Ge10Te80Se10-xGax (x = 0, 2, 4, 6, 8, 10 at %) bulk chalcogenide glassy alloys have been synthesized via melt quench technique. The role of Ga is studied through a semi-empirical approach. The result shows that the system is in rigid mode (total number of mechanical constraints >3). The density of the system shows an increase which is further supported by a decrease in free volume percentage. Mean bond energy and glass transition temperature have also been investigated. The energy gap shows a decrease with increase in Ga at. % and the behavior are correlated with the decrease in average single bond energy (72.7 kJ/mol to 69.7 kJ/mol) and electronegativity (2.14–2.06) of the system. From the results of covalent character (>90%), it is estimated that the compositions may be used to form stable glasses, which may be helpful in the development of an infrared system.

In this work, un-doped and manganese ion (Mn2+)-doped zinc selenide (ZnSe) quantum dots (QDs) were investigated by measuring photoluminescence (PL) and photoluminescence excitation (PLE) spectra in the temperature range from 300 to 77 K. Intense blue and orange PL were observed for ZnSe and Mn@ZnSe QDs, respectively. The intensity of PL spectra is found to be exceedingly dependent on temperature. The highest PL intensity is obtained at 77 K and then reduced with rising temperature up to 300 K. To understood the temperature-dependent PL origin and mechanism, the PL spectra with different excitation and PLE spectra at different PL wavelengths were investigated at decreasing temperature (300 - 77 K) and vis-a-vis. The calculated activation energy values come out to be 42.2 and 66.4 meV for ZnSe and Mn@ZnSe QDs, respectively. Furthermore, the lifetimes of Mn@ZnSe QDs were discussed at different temperatures. The absolute sensitivity (S) for the temperature sensor is calculated, and the maximum S values come out to be 0.58% K−1 at 225 K and 0.44% K−1 at 250 K for ZnSe and Mn@ZnSe QDs, respectively. The wide range linearity in temperature-dependent PL and moderate activation energy values suggest that the prepared QDs can be cast for a PL-intensity-based optical temperature sensor.

Se–Te materials have shown promise in optoelectronic applications. A combination of enhanced optical and mechanical properties represents a good candidate for optical limiting devices. Here, we report the influence of Ag additive on the optical and mechanical properties of ( S e 70 T e 30 ) 100 − x A g x ( 0.0 ≤ x ≤ 8.0 a t . % ) chalcogenide thin films. The reflectance spectra of amorphous thin films have been analyzed in the spectral range 0.3 μm–2.5 μm. The optical parameters are obtained using reflectance spectra of the thin films. The refractive index increases with the addition of Ag, while the optical band gap decreases from 1.40 eV to 1.11 eV. The reduction in the optical band gap is correlated with the raise in the concentration of defect states and the disorder. The nonlinear refractive index and nonlinear susceptibility have been evaluated and found to show an augmented response with Ag content. The value of ( χ ( 3 ) ) increases from 3.44 × 10−11 esu to 7.66 × 10−11 esu and n2 from 3.98 × 10−10esu to 8.08 × 10−10esu. The mechanical properties have also been analyzed theoretically and ultrasonically with Ag incorporation to SeTe thin films.

In this work, the effect of visible light on the structural, morphological and optical properties of $$(\hbox {Ge}_2\hbox {Sb}_2\hbox {Te}_5)_{100-x}\hbox {Ag}_x$$ ( $$\hbox {x} = 0, 1$$ and 3) thin films prepared by thermal evaporation was studied. Deposited thin films were exposed to visible light of intensity $$10^{4}$$ and $$10^{5}$$ Lux for the duration of 2, 4, 8 and 20 h. Prepared samples were characterized with X-ray diffraction (XRD), Scanning electron microscope (SEM) and UV–Vis–NIR spectrophotometer. The amorphous nature of as-deposited and visible light exposed thin films was confirmed by XRD. The SEM images did not show significant change in the morphology of thin films after visible light exposure. The optical transmission of as-deposited and exposed thin films was measured by UV–Vis–NIR spectrophotometer in the wavelength range of 500–3300 nm. Optical transmission was used to calculate the absorption coefficient and optical band gap. Photo-darkening (decrease in optical band gap) with light exposure was observed in $$(\hbox {Ge}_2\hbox {Sb}_2\hbox {Te}_5)_{100-x}\hbox {Ag}_x$$ ( $$\hbox {x} = 0, 1$$ and 3) thin films. Photo-darkening may be attributed to the enhanced lone pair-lone pair interactions which broaden the valence band and hence decrease the optical band gap. Thus, change in optical parameters is because of change in local structure of deposited thin films.

Mn-Zn ferrites have shown various remarkable applications e.g. in magnetic amplifiers, power transformers and electromagnetic interference etc. due to their high initial permeability. Mn–Zn ferrite powder ( Mn 0.5 Zn 0.5 Fe 2 O 4 ) has been prepared by the co-precipitation method and subsequently sintered at three different temperatures i.e. 973 K, 1173 K, 1373 K. Optical properties have been correlated with the structural properties. For structural properties X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy (FTIR) have been employed. It has been observed that there is an increase in crystallite size with sintering from 973 K to 1373 K and FTIR confirms the formation of bond between metal ion and oxygen ion at the octahedral site and tetrahedral site. A red shift has been confirmed from UV–visible absorption spectra and photoluminescence spectra have been reported with an increase in sintering temperature.

Superparamagnetic nanoparticles are very important in biomedicine due to their various applications like drug delivery, gene delivery in the body and also used for hyperthermia. In the present work, superparamagnetic nanoparticles of Mn 0.5 Zn 0.5 Gd x Fe 2-x O 4 ( x = 0, 0.025, 0.050, 0.075, 0.1) ferrites have been prepared by co-precipitation method. Thorough characterizations (XRD, FTIR, FE-SEM, EDS, VSM and fluorescence spectroscopy) have proved the formation of cubical spinel superparamagnetic nanoparticles of soft ferrites. A cation distribution has been proposed for the determination of various important theoretical parameters for these samples. With the addition of Gd 3+ nanoparticles have shown the superparamagnetism at room temperature confirmed by VSM analysis. Photoluminescence (PL) spectra shows a blue shift (for x = 0.025, 0.075) which may be due to quantum confinement.

Ge2Sb2Te5 (GST) is considered to be one of the most prominent phase change materials for data storage applications. The UV–Vis–NIR transmittance spectra of (Ge2Sb2Te5)100-xSmx (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2) thin films are utilized to analyze the effect of rare earth element Sm on the optical behaviour of GST. The linear and nonlinear optical studies of GST on Sm incorporation provide the understanding of electron transport properties and band structural details. The optical parameters such as absorption coefficient (α) and the refractive index are obtained through transmission data and are analyzed for Sm doped GST thin films. There is significant change of the absorption coefficient near the optical band gap for (Ge2Sb2Te5)100-xSmx thin films. The optical dispersion parameters are analyzed to understand the material's structure. The optical band gap, Urbach energy, and disorder of Sm doped GST thin films are analyzed for band structure modification details on Sm addition. The free career concentration to electron effective mass ratio and high-frequency dielectric constant for (Ge2Sb2Te5)100-xSmx thin films are analyzed. Optical conductivity, dielectric constant, surface and bulk energy loss function and tan δ loss function for (Ge2Sb2Te5)100-xSmx thin films are obtained. The optical non-linear parameters are analyzed to understand the dependence of the polarizability of GST on Sm addition. The incorporation of Sm leads to the change in local bonding environment which may improve the switching mechanism of phase change memory devices.

Chalcogenide glasses (ChG) has emerged as important materials due to their potential applications in infrared optics for communication, imaging, limiting, remote sensing and laser power delivery etc. Examining ChG for their various applications, different properties of these were under immense investigation by various researchers from nearly every part of the world. Study of ChG for optical properties like optical band gap and refractive index are the backbone while considering them for applications. The present review focuses on the optical properties of various binary, ternary and quaternary chalcogenide systems. Subsequently applications and future prospects of ChG have been sketched. The attracting prospective applications have drive us to put the review on optical properties of chalcogenide thin films both comprehensive and expedient to new as well as established researchers in this area.

In this work, manganese doped zinc selenide (Mn@ZnSe) quantum dots (QDs) were prepared via a direct aqueous route. The X-ray diffraction pattern reveals the crystalline cubic zinc blende structure of QDs. With Mn2+ doping, a new high-intensity orange photoluminescence (PL) band centered at around 580 nm obtained owing to 4T1 → 6A1 of Mn2+ ion transitions (for orange QLEDs). The freshly prepared water-dispersible QDs were treated under the UV-radiation for the photoactivation process, which enhanced the PL quantum efficiency from 5 % to 17.3 %. The response of QDs towards different metals was recorded in terms of absorption, PL and PL-lifetime. Among the numerous metals, Pb2+ shows strong PL quenching and the corresponding Stern-Volmer plot showed linearity with the detection limits of 29.8 × 10−6 M in ultrapure water. The developed Mn@ZnSe QDs could act as a non-toxic sensor to sense hazardous lead in drinking water.

In present investigation, the effect of phase change, induced via sintering, from hematite (Fe2O3) to pure spinel structure on structural and optical properties in coprecipitated Mn0.4Zn0.6Fe2O4 nanoferrites has been studied. The Mn0.4Zn0.6Fe2O4 nanoparticles have been sintered at three temperatures 700 °C, 900 °C, and 1100 °C for 3 h. The presence of hematite (Fe2O3) phase in samples sintered at temperatures 700 °C and 900 °C has been observed from XRD. The crystallite size of the sintered samples has been found to increase on increasing the sintering temperature from 700 °C to 900 °C and then decrease for 1100 °C. Pure cubic spinel structure having single-phase has been obtained at 1100 °C. A cation distribution has also been proposed. Two absorption bands in the range 445 cm−1-473 cm−1, as well as 556 cm−1-582 cm−1, have been recognized in FTIR spectra and that indicates the formation of metal ion oxygen bond in spinel structure. With the rising sintering temperature, the peak position in the absorption spectra has been noticed to shift toward lesser wavelength, i.e., from 266 nm to 261.18 nm. The optical band gap shows shrinkage with the augmentation in the crystallite size on elevating the sintering temperature from 700 °C to 900 °C, while the optical band gap shows a broadening on raising the sintering temperature to 1100 °C. Photoluminescence study on the sintered samples has also been performed to examine the impurity levels and defects in samples. Stokes shift has been observed in all three samples.

The phase change materials (PCM) are recognized for their use in optical and electrical memory devices. The stability of phase change control depends on the effective alteration of structural configurations. The structural transitions of Ge2Sb2Te5 (GST) PCM on Samarium (Sm) addition are investigated. The possibility of structural units to attain various configurations on Sm addition and their stability are theoretically analysed using the negative correlation energy barrier. The phase change phenomenon of Sm added GST is explained through the bond alternation mechanism. The criterion for the structural modification efficiency (CSME) is calculated from metallicity (M) values. The increase in the values of M and CSME signifies an increase in the rigidity of the network and the possibility of formation of various structural configurations during phase transition respectively. The threshold switching voltage is calculated and found to increase on Sm addition to GST indicating faster crystallization speed for efficient storage applications.

Cd 1− x Co x S dilute magnetic semiconductor nanofilms (0≤ x ≤0.08 at%) deposited by chemical bath deposition have been investigated using grazing angle x-ray diffraction, atomic force microscopy and vibrating sample magnetometer. The introduction of Co 2+ ions in CdS structure induces structural disorders and hence, results in degradation of crystallinity. The crystallite size, interplanar spacing and lattice parameter ratio decrease with increasing Co 2+ concentration in CdS. The diamagnetic state of CdS disappears with increase in Co concentration and films with x >0.02 exhibit ferromagnetism. This may be explained in terms of the spin–orbit interactions and Co 2+ ion induced the lattice defects and phase separation.

Tellurium-based glasses are suitable for storage devices due to their rapid amorphous-to-crystalline transformation. Alloys of Ge 19−y Se 63.8 Sb 17.2 Te y (y = 0, 2, 4, 6, 8, 10 at.%) have been synthesized using melt quench technique. Glass transition and crystallization kinetics of alloys have been investigated using differential thermal analysis at different heating rates (5, 10, 15, and 20 K min−1). The thermal stability of synthesized alloys has been investigated. Resistance to devitrification has been analyzed on the basis of activation energy for crystallization.

We report linear and non-linear optical properties of a new quaternary chalcogenide glass series Ge19-ySe63.8Sb17.2Tey (y = 0, 2, 4, 6, 8, 10). In linear optical properties; refractive index, extinction coefficient and the Tauc gap are reported and their variation with Te content has been discussed. In non-linear properties; third order nonlinear susceptibility and non-linear refractive index has been discussed. The variation of non-linear refractive index has also been reported with normalized photon energy. A correlation between the Tauc gap and nonlinear refractive index has been discussed. Results indicate that these materials may find applications in modern optical devices.

Steady state current-voltage characteristics of the amorphous (Se80Te20)98Y2 (Y = Ag, Bi, Ge, Cd) semiconductors at different temperatures are reported. The measurements were performed using direct-current voltage bias to understand the basic conductivity mechanism and to evaluate the impact of each substituent on electrical response. The space charge limited conduction mechanism, and the density of states near Fermi level have been calculated. The difference in electrical response due to different substitutions in the glassy matrix is analyzed.

Chalcogenide glasses are remarkable materials for remote sensors, infrared imaging and infrared fibers due to their transparency in Far-infrared (IR) region. Far-IR absorption spectra of Ge 19 Se 81 − x Sb x ( x = 0, 4, 8, 12, 16, 17.2, 20) and Ge 19 − y Se 63.8 Sb 17.2 Te y (y = 0, 2, 4, 6, 8, 10) have been obtained in the range of 30–350 cm − 1 . Three possible bond arrangement approaches viz . chain-crossing model (CCM), random-covalent-network model (RCNM) and chemical bond approach (CBA) have been used to discuss the formation of bonds. Results are explained on the basis of GeSe 4 , GeSe 2 and SbSe 3 isolated structural units which have appeared in Ge–Se–Sb system while Se 6 Te 2 rings, GeTe 4 tetrahedron, GeTe 2 , GeSe 4 and GeSe 2 structural units have appeared for Ge–Se–Sb–Te system.

Chalcogenide glasses find extensive applications in infrared (IR) devices and optical communication. Optical parameters of Sb10Se65Ge25−yIny thin films, deposited by the thermal evaporation technique, have been analyzed using ultraviolet–visible-near IR spectroscopy. The transitions in the forbidden gap are indirect. The effect of indium (In) alloying on the nonlinear optical parameters has been studied. A shift in optical absorption edge towards higher wavelength shows that the width of the localized states changes, which affects the optical parameters of the system. The high nonlinearity of these glasses makes them suitable for optical regeneration and Raman amplification.

Chalcogenide glasses are promising materials for threshold and memory switching. Alloys of Ge19Se81 − xSbx (x = 0, 4, 8, 12, 16, 17.2, 20) have been prepared by melt quench technique. Differential thermal analysis has been used to characterize samples at different heating rates (α = 5, 10, 15, 20 K/min). Glass transition temperatures, crystallization temperature, melting temperature, activation energy for glass transition and crystallization have been determined. Thermal stability of alloys has been analyzed in terms of ease by which atomic rearrangements take place and the resistance to devitrification. The correlation between thermal stability and glass forming ability has also been studied.

Differential thermal analysis (DTA) has been employed to investigate the effect of Ge addition on the glass transition behavior and crystallization kinetics of Sb10Se90−xGex (x = 0, 19, 21, 23, 25, 27) alloys. The three characteristic temperatures viz. glass transition (T g), crystallization (T c), and melting (T m) have been determined and found to vary with the heating rates and Ge content. Thermal stability and glass forming tendency have been evaluated in terms of ΔT (= T c − T g) and reduced glass transition temperature. The activation energies for glass transition and crystallization have been used to analyze the nucleation and growth process. The activation energy analysis also determines the suitability of alloys to be used in switching applications. Results have been interpreted in terms of bond energies and structural transformations in the investigated alloys.

Chalcogenide glasses exhibit good optical properties because of their ability to transmit in the infrared region. Far-Infrared transmission spectra give an insight into the absorbed frequencies of the light corresponding to the characteristic vibration of the isolated molecular units. Ge and In have been used as additives in Sb10Se90 and Sb10Se65Ge25 alloys, respectively. The role of Ge on the formation of a 3-dimensional network, through the apparition of GeSe4 and GeSe2 units at the expense of SbSe3 and Se8 groups, is evidenced, due a higher tendency of Ge to spontaneously form linkages with the other elements of the medium. When Ge is substituted by In, the glass rearranges due to the progressive disappearance of GeSe2 and GeSe4 units. SbSe3 and Se8 reappear accompanied by InSe4 and In–In units. These results are comforted by the calculation of the bond probabilities and vibration frequencies.

Chalcogenides are promising material for various optical applications. Transmission spectra of thermally evaporated thin film of Ge19Se81−xSbx (where x = 0, 4, 8, 12, 16, 17.2, 20) have been obtained in the spectral range of 400–2400 nm. Refractive index has been found to increase with increase in Sb content while optical band gap has been found to decrease up to x = 17.2 and thereafter increases. The results have been explained on the basis of change in the density of dangling bonds. Results indicate that the observed characteristics favour the application of these materials in optical filters.

The present article deals with the differential scanning calorimetric (DSC) study of Se–Te glasses containing Sn. DSC runs are taken at four different heating rates (10, 15, 20 and 25 K min−1). The crystallization data are examined in terms of modified Kissinger, Matusita equations, Mahadevan method and Augis and Bennett approximation for the non-isothermal crystallization. The activation energy for crystallization (E c) is evaluated from the data obtained at different heating rates. Activation energy of glass transition is calculated by Kissinger’s relation and Moynihan theory. The glass forming tendency is also calculated for each composition. The glass transition temperature and peak crystallization temperature increases with the increase in Sn % as well as with the heating rate.

Chalcogenide glasses are suitable for far-infrared and imaging applications. In the present study, Sb10Se90-xGex (x=0, 19, 21, 23, 25, 27) system has been chosen to study structural transformations via physical parameters. Bulk samples with x = 0, 19, 21, 23, 25 and 27 have been prepared using the melt-quenching technique. A theoretical study of the ternary glass system revealed that there was a significant change in the structural environment of the system due to rigidity percolation, which took place as Se was replaced by Ge, and hence resulted in changes in other physical parameters of the system.

Selenium-based glasses are attractive candidate materials because of their low transmission losses and other optical properties. In the present paper, samples of Ge19Se81-xSbx (x = 0, 4, 8, 12, 16, 17.2, 20) were prepared by using the melt-quench technique, and their X-ray diffraction spectra were studied. Some of the physical parameters were calculated theoretically. It was observed that the glass transition temperature increased up to x = 17.2 and then decreased whereas the theoretically calculated band-gap decreased with increasing Sb content.

Se–Te alloys are an important system of chalcogenide glasses from application point of view. The incorporation of Sn additive alters the electrical properties of these alloys. The conductivity measurements have been done on the thin films of a-Se85−xTe15Snx (x = 0, 2, 4, 6 and 10 at.%) deposited using vacuum evaporation technique. Both dark (σd) and photoconductivity (σph) show a maximum for x = 6 at.% of Sn, which, decreases on further Sn addition to the binary Se–Te alloy. The dark activation energy (ΔEd) shows a minimum for x = 2 at.% of Sn, but increases on further Sn addition. There is a sharp decrease in photosensitivity (σph/σd) on Sn addition to Se85Te15 alloy. The charge carrier concentration (nσ) calculated with the help of dc conductivity measurements also show a maximum at x = 6 at.% of Sn. The results are explained on the basis of increase in the density of localized states present in the mobility gap on Sn incorporation.

The effect of thermal annealing on the electrical and structural properties has been studied on a thin film of a-Se85Te15 alloy. The dark (σd) and photo-conductivity (σph) increase sharply with the increase in annealing treatment. There is a sharp drop in the photosensitivity (σph/σd) of the thin film sample. The dark activation energy (ΔEd) decreases on thermal annealing treatment. These changes are attributed to the phase transition of the thin film of a-Se85Te15 from amorphous to crystalline phase. This is supported by the x-ray diffraction measurements, which clearly indicate the said phase transition on subjecting the thin film to prolonged thermal annealing treatment.

Electrical measurements have been carried out on a-(Ge 20 Se 80 ) 100− x Cu x ( x = 0.0, 0.5, 1.0, 1.5 and 2.0 at.%) thin films. The dark conductivity ( σ d ) and photoconductivity ( σ ph ) measurements are done in the temperature range 252–349 K. The values of σ d , σ ph increase and dark activation energy (Δ E d ), photo activation energy (Δ E ph ) decrease as the concentration of Cu additive increases (up to 1.0 at.%). Photosensitivity ( σ ph / σ d ) increases and decay time constant ( τ d ) decreases as the concentration of Cu increases (up to 1.0 at.%). The charge carrier concentration ( n σ ) increases with Cu incorporation (up to 1.0 at.%). A reverse in the trend takes place in all these parameters as the Cu concentration is further increased (>1.0 at.%). These results are explained on the basis of change in the density of defect states present in the mobility gap of Ge–Se–Cu alloy.

Electrical measurements are done on Se85−xTe15Inx (x = 0, 2, 4, 6 and 10 at%) thin films. The dark conductivity (σd) increases and the activation energy (ΔEd) decreases as the In concentration increases. The photoconductivity (σph) also increases with the increase in In concentration. The photosensitivity (σph/σd) decreases sharply after the In incorporation. The charge carrier concentration (nσ) is calculated with the help of dc conductivity measurements. The value of nσ increases as the In concentration increases. The results are explained on the basis of an increase in the density of localized states present in the mobility gap.

Nickel-doped cadmium sulphide dilute semiconductor nanofilms (Cd1−x Ni x S, 0 ≤ x ≤ 0.09) have been investigated using atomic force microscopy, scanning electron microscopy, Fourier infrared transform and UV–Vis spectroscopy. With increasing Ni content a decrease in average crystallite size (26–10 nm) and surface roughness has been found. A red shift in optical band gap has been observed with decrease in average crystallite size, which is against quantum confinement.

Se based glasses are suitable optical materials and may be used for high speed communication fibers. Third order nonlinear susceptibility has been evaluated from changing refractive index using Wang approximations. Nonlinear behavior of Ge19Se81−xSbx (where x = 0, 4, 8, 12, 16, 17.2, 20) has been predicted using suitable relation between linear refractive index and nonlinear refractive index.

Third order non-linear optical properties are of great interest because of their potential applications in telecommunication devices. Third order non-linear susceptibility (χ(3)) and non-linear refractive index (n2) of SbSeGe glassy alloys have been calculated using linear refractive index and Wemple DiDomenico parameters. The values of χ(3) and n2 decrease as Ge concentration increases in the Sb10Se90 system.

We have grown 45–60 nm thick uniform smooth cadmium sulphide (CdS) nanofilms via a chemical bath deposition technique at different deposition temperatures (Td = 50, 60, 70, 80 and 90 °C) and these have been studied using x-ray diffraction, scanning electron microscopy, atomic force microscopy and a UV–Vis–NIR spectrophotometer. The growth rate increases with increasing Td up to 70 °C and then decreases. The structural analysis shows that CdS nanofilms exist in cubic or polymorph phases. The surface analysis indicates that the morphology of the films changes with increasing Td. CdS nanofilms grown at Td = 70 °C show high transmittance, low absorbance with a higher band gap.