Lateral Correlation Length Research Articles

Effect of As4 beam equivalent pressure on the growth dynamics of InAs films grown at low temperature on graphene layers

The present study investigates the growth of InAs films at low temperature on graphene synthesized via molecular beam epitaxy, emphasizing the effect of As4 beam equivalent pressure (5.0 × 10⁻6 Torr (low) and 4.5 × 10⁻⁵ (high)) on the growth dynamics. X-ray diffraction, scanning electron microscopy, and atomic force microscopy, along with correlation functions, revealed that monitoring the As4 beam equivalent pressure affects the structural properties of polycrystalline InAs films grown on the graphene/Si layer. The film thickness (particle size) was found to be 172 ± 10 nm and 216 ± 10 nm (40 ± 2 nm and 42 ± 2 nm) for the InAs layers grown at low and high As4 beam equivalent pressure. The increase in the film thickness and particle size with increasing the As4 beam equivalent pressure is attributed to improved material availability and surface kinetics due to the large migration energy of As compared to In and hence the larger diffusion length of In. Conversely, decreasing As4 beam equivalent pressure raises the roughness scaling exponent and enlarges interface width (0.17 µm and 0.31 µm for films grown at high and low As4 beam equivalent pressure) and lateral correlation length, implying smoother surfaces due to larger particles. These insights are pivotal for fabricating advanced semiconductors, underscoring As4 beam equivalent pressure's role in optimizing InAs films for electronic and optoelectronic applications.

Impact of fractal dimension and lateral correlation length on surface plasmon resonance activity in sputtered silver layers

Fractal and optical characteristics of self-affine surfaces of silver(Ag) thin films deposited through direct current (dc) magnetron sputtering as a function of thickness are investigated and explored here. The surface morphology of Ag thin films is characterized by field emission electron microscopy, and atomic force microscopy technique. The cube counting algorithm is used to extract the fractal dimension of Ag thin film. The surface roughness (interface width) shows monotonic increases with film thickness, while the other parameters, such as lateral correlation length, roughness exponent, and fractal dimension exhibit linear variation with thickness. Our findings reveal distinctive scaling behaviors, with scaling exponents α, β, and 1/z indicating unique growth characteristics. The interface width w increases as a power law of thickness t, w(t)∝tβ, with β=0.39± 0.007, and the lateral correlation length ξ grows as ξt∝t1/z with 1/z=0.14± 0.002. The roughness exponent extracted from height-height correlation analysis is α=0.61–0.41. The self-affine nature of the Ag thin films is further confirmed by the autocorrelation function. X-ray photoelectron spectroscopy (XPS) is used to the confirm the growth of Ag thin film. Additionally, we have studied the role of fractal dimensions and lateral correlation length (ξ) on the surface plasmon resonance (SPR) of Ag thin film. Our results indicate a red-shifting behavior of SPR with increasing interface width (w), lateral correlation length (ξ), and fractal dimensions. This study suggests the significance of not only the roughness exponent and fractal dimension but also the local surface slope in SPR activity in Ag thin films.

Effect of Annealing on Stress, Microstructure, and Interfaces of NiV/B4C Multilayers

The functionality and reliability of nanoscale multilayer devices and components are influenced by changes in stress and microstructure throughout fabrication, processing, and operation. NiV/B4C multilayers with a d-spacing of 3 nm were prepared by magnetron sputtering, and two groups of annealing experiments were performed. The stress, microstructure, and interface changes in NiV/B4C after annealing were investigated by grazing-incidence X-ray reflectometry (GIXR), grazing-incidence X-ray diffraction (GIXRD), X-ray diffuse scattering, and grazing-incidence small-angle X-ray scattering (GISAXS). The temperature dependence experiments revealed a gradual shift in the multilayer stress from compression to tension during annealing from 70 °C to 340 °C, with the stress approaching near-zero levels between 70 °C and 140 °C. The time-dependent experiments indicated that most of the stress changes occurred within the initial 10 min, which showed that prolonged annealing was unnecessary. Combining the X-ray diffraction and X-ray scattering measurements, it was found that the changes in the thickness, interface roughness, and lateral correlation length, primarily due to crystallization, drove the changes in stress and microstructure.

Surfaces properties correlation with optical parameters of thickness dependent self-affine nanostructured SnS thin films: A study based on scaling law

Fractal concepts are employed to investigate the surface properties of tin sulfide (SnS) thin films, which are deposited on Fluorine-doped tin oxide (FTO)- coated glass substrates by the thermal evaporation (TE) technique. The surface topography of each deposited film is captured by AFM. The fractal dimensions of the AFM image were extracted through the Higuchi algorithm, and it is found that the thinner sample surface exhibits the maximum fractal dimension. The autocorrelation function and height-height correlation function are used to investigate the self-affinity behavior of surfaces. Dynamic surface roughening is characterized by different scaling exponents, such as the roughness exponent, the growth exponent, the dynamic scaling exponent, and the steepening exponent. It was observed that the values of average roughness, interface width, lateral correlation length, and mean square local slope are strongly influenced by film thickness. The self-affine fractal nature of thin film is estimated by the roughness exponent; however, island- or mound-type growth with quick surface roughening behavior is predicted by the growth exponent and the dynamic scaling exponent. Further, we have tried to correlate the optical properties such as transmission, reflection, and refractive index with the fractal dimension of SnS thin film. The increase in optical reflection with decreasing roughness indicates that absorber surfaces of the best crystalline films have the lowest reflectivity. The present results suggest that such surfaces, having a maximum fractal dimension and minimum optical reflectance, can be used as photon absorber layers for advanced solar cell devices.

Visualization and quantification of microphase separation in thermoplastic polyurethanes under different hard segment contents and its effect on the mechanical properties

The microstructure and macroscopic properties of thermoplastic polyurethanes (TPUs) are significantly affected by their microphase separation. It is therefore of great interest to quantitatively characterize the microphase separation of TPUs and explore its connection with their mechanical properties. In this work, a method based on atomic force microscopy is proposed to visualize and quantify the microphase separation of polyether TPUs with different hard segment contents. The lateral correlation length was proposed to describe the scale of microphase separation and the microscopic Young's modulus distributions were also obtained for comparison. Results show that the macroscopic Young's modulus of the polyether TPU is consistent with the microscopic Young's modulus only when the lateral correlation length reaches a certain threshold. Besides, the studied polyether TPU exhibits the best overall mechanical properties when it reaches the maximal lateral correlation length. The proposed AFM-based method demonstrates a versatile analytical tool for quantitatively assessing the microphase separation and unveiling the relationship between the microphase separation, microscopic mechanical properties, and the macroscopic properties of TPUs.

Interface and crystallization evolution induced by reactive nitrogen and oxygen sputtering in Ni/Ti multilayer

Ni/Ti multilayers were reactively deposited with a gas mixture of Ar, N2 and O2 using the magnetron sputtering, while (N2 + O2)/Ar flow ratio during the sputtering process was varied. A detailed study on the microstructure evolution and interfacial properties was performed using grazing incidence X-ray reflectivity, X-ray diffraction, X-ray photoelectron spectroscopy, X-ray diffuse scattering, and transmission electron microscopy. With the increase in (N2 + O2)/Ar flow ratio, the grain size in Ni layers first decreases and then increases at a critical point of 25.0 %, followed with the crystal phase transforming from Ni into NiO. The mechanism of microstructure evolution in Ni layers due to N2 and O2 gas incorporation is discussed in this paper. The interfaces of Ni/Ti multilayer are smoothened due to a decrease in the size of Ni grains. Meanwhile, the interfacial effects including the vertical replication of interfacial roughness and the diffusion between adjacent Ni and Ti layers are suppressed for the N2 and O2 gas incorporation. Furthermore, the lateral correlation length of interfacial roughness varies with (N2 + O2)/Ar flow ratio, which presents the relevance with the grain size.

Interface study on the effect of oxygen/nitrogen ratio in Ni/Ti multilayer deposited by reactive sputtering

Since the growth morphology along and perpendicular to the interface is important for supermirror applications, the dependence of this on the reactive gas has been investigated in Ni/Ti multilayers prepared by reactive magnetron sputtering with variable O2/N2 ratios. The interface properties are characterized by GIXRR, XDS, and TEM measurements. Compared to the case without O2, the presence of 20% O2 in the deposition of Ni layers contributes to smooth and abrupt interfaces. It also suppresses the accumulation of interfacial roughness with the increasing number of layers. However, the abundant oxygen content results in a striking degradation of interface quality associated with the crystallization evolution. Moreover, the lateral correlation length of interfacial roughness exhibits a consistent tendency with the grain size as the oxygen content increases. Following the XPS depth profiles, although N2 and O2 gases were applied in the Ni layer deposition, the N and O were only detected in the Ti layers as the compound for the high chemical activity of Ti. The elemental form in the Ni layers corresponds to the crystalline structure inferred by XRD measurements.

Growth dynamics and its correlation with plasmonic properties of silver nanoparticles grown by solid state dewetting

Surface morphology and growth dynamics of silver nanoparticles grown by solid-state dewetting of sputtered precursor silver films are studied using atomic force microscopy (AFM) with advanced statistical analysis. Height-height correlation function (HHCF) and power spectral density function (PSDF) were extracted from AFM data, and scaling exponents αlocal,β,1/z and α were determined using analysis. HHCF analysis reveals that interface width w follows power law dependence with precursor film thickness (t) as ∼t0.48±0.01 for as-deposited films and ∼t1.27±0.08 for annealed films. Similarly, lateral correlation length ξ is observed to scale with precursor film thickness as ∼t0.58±0.08 for as-deposited films and ∼t0.65±0.05 for annealed films. The HHCF and PSDF analysis confirmed mound-like growth of the nanoparticles for the higher thickness of the precursor films. A direct correlation between morphology and the localized surface plasmon resonance (LSPR) properties of the silver nanoparticles is also observed.

Interface tomography of GaInAs/AlInAs quantum cascade laser active regions

We present a high-resolution electron tomography study of buried ultra-thin layers and their interfaces from the active region of a (Ga,In)As/(Al,In)As quantum cascade laser (QCL) test structure. Using a high-angle annular dark-field scanning transmission electron microscopy image series, a three-dimensional (3D) reconstruction of the complex layer structure is obtained. From this 3D information, we determine quantitative values for the chemical width and, simultaneously and independently, the root mean square roughness (rms) and lateral correlation length of the individual interfaces of a cascade using topographic height maps. The interfacial widths are comparably small for all interfaces within a cascade and the layer thicknesses show only a small standard deviation of less than one monolayer. The rms roughness is systematically lower at the direct (Ga,In)As-on-(Al,In)As interface compared to its inverse. In addition, using the one-dimensional height–height correlation function, different lateral correlation lengths along the two perpendicular in-plane directions are detected indicating a distinct anisotropy of the interface morphology. Our accurate and comprehensive results on the QCL test structure will serve as feedback to evaluate the growth process and help to assess the performance of corresponding future laser devices in detail.

Fractal characterizations of MeV ion treated CaF2 thin films.

We present the morphological evolution and fractal characterizations of CaF2 thin-film surfaces modified by bombardment with 100 MeV Au+8 ions at various fluences. Atomic force microscopy (AFM) combined with line profile and two-dimensional power spectral density (2D-PSD) analysis was utilized to investigate the evolution of surface morphology as a function of fluence. The AFM images were utilized to investigate the relationship between fractal dimension, roughness exponent, lateral correlation length, and ion fluence. The surface erosion owing to sputtering was depicted using Rutherford backscattering spectrometry. The structural characteristics' dependency on fluence was explored with the help of glancing angle x-ray diffraction measurements on virgin and irradiated samples. Tensile stress calculated using a peak shift in the glancing angle x-ray diffractogram showed an increase in tensile stress with fluence that caused the surface to crack after the fracture strength of the surface was crossed. 2D-PSD analysis signified the role of sputtering over surface diffusion for the observed surface modifications. Fractal dimensions first increased and then decreased with ion fluence. The lateral correlation length decreased, while the roughness exponent increased with fluence after the threshold value.

Seismic amplitude response to internal heterogeneity of mass-transport deposits

Abstract. Compared to unfailed sediments, mass-transport deposits are often characterised by a low-amplitude response in single-channel seismic reflection images. This “acoustic transparency” amplitude signature is widely used to delineate mass-transport deposits and is conventionally interpreted as a lack of coherent internal reflectivity due to a loss of preserved internal structure caused by mass-transport processes. In this study we examine the variation in the single-channel seismic response with changing heterogeneity using synthetic 2-D elastic seismic modelling. We model the internal structure of mass-transport deposits as a two-component random medium, using the lateral correlation length (ax) as a proxy for the degree of internal deformation. The average internal reflectivity is held approximately constant with increasing deformation by fixing the two component sediment lithologies to have realistic P-wave velocity and density based on sediment core measurements from the study area. For a controlled single-source synthetic model a reduction in observed amplitude with reduced ax is consistently observed across a range of vertical correlation lengths (az). For typical autonomous underwater vehicle (AUV) sub-bottom profiler acquisition parameters, in a simulated mass-transport deposit with realistic geostatistical properties, we find that when ax≈1 m, recorded seismic amplitudes are, on average, reduced by ∼25 % relative to unfailed sediments (ax≫103 m). We also observe that deformation significantly larger than core scale (ax>0.1 m) can generate a significant amplitude decrease. These synthetic modelling results should discourage interpretation of the internal structure of mass-transport deposits based on seismic amplitudes alone, as acoustically transparent mass-transport deposits may still preserve coherent, metre-scale internal structure. In addition, the minimum scale of heterogeneity required to produce a significant reduction in seismic amplitudes is likely much larger than the typical diameter of sediment cores, meaning that acoustically transparent mass-transport deposits may still appear well stratified and undeformed at core scale.

Numerical Investigation of GaN HEMT Terahertz Detection Model Considering Multiple Scattering Mechanisms.

GaN high-electron-mobility transistor (HEMT) terahertz (THz) detectors have been widely studied and applied in the past few decades. However, there are few reports about the influence of GaN/AlGaN heterostructure material properties on the detection model at present. In this paper, a response voltage model for a GaN HEMT THz detector that considers the carrier scattering in a GaN/AlGaN heterostructure is proposed. The phonon scattering, dislocation scattering, and interface roughness scattering mechanisms are taken into account in the classic THz response voltage model; furthermore, the influence of various material parameters on the response voltage is studied. In a low-temperature region, acoustic scattering plays an important role, and the response voltage drops with an increase in temperature. In a high temperature range, optical phonon scattering is the main scattering mechanism, and the detector operates in a non-resonant detection mode. With an increase in carrier surface density, the response voltage decreases and then increases due to piezoelectric scattering and optical phonon scattering. For dislocation and interface roughness scattering, the response voltage is inversely proportional to the dislocation density and root mean square roughness (RMS) but is positively related to lateral correlation length. Finally, a comparison between our model and the reported models shows that our proposed model is more accurate.

Carbon ion beam induced chemical modification and nano-pyramid growth on Si surface

We report the growth of nano-ripple on, initially smooth Si surface due to chemically guided additional instability generation during 10 keV C+ bombardment at grazing (70°) ion incidence. Also, the transformation of the ripple structure to triangular nano-pyramidal structure at higher ion fluence is investigated in details. It is shown that the chemical nature of the surface changes due to silicon carbide formation at the ion impact sites, and the surface becomes a mixture of Si and SiC. The differential sputtering of Si from pure Si and SiC, generates an additional instability which leads to trigger the ripple pattern on the surface. The variation of height amplitude, lateral correlation length and slope angles of the developed structures are investigated and explained in terms of existing continuum theory. At very high ion fluence the transformation of the structure into three dimensional triangle (pyramidal) is revealed and the mechanism is explained in the light of variation of local ion impact angle and its consequent effects.

Multilayer Langmuir Film of Monodisperse Au Nanoclusters: Unusual Growth via Bilayers

The assembly of nanomaterials into thin films is an important area in the nanofabrication of novel devices. The monodispersity of nanoparticles plays an essential role in the resulting quality of the assembled mono- and multilayers. Larger polydispersity leads to smaller lateral correlation lengths and smaller domains of aligned nanoparticles, thus resulting in more point and line defects. Perfectly monodisperse nanoparticles should therefore minimize the number of defects in the assembled films. Despite tremendous progress in reducing the polydispersity of nanoparticles, there has been limited research on the assembly of thin films out of perfectly monodisperse nanoclusters. Here, we show a formation of Langmuir films using perfectly monodisperse gold nanoclusters with composition Au32(nBu3P)12Cl8 exhibiting a diameter of 1.8 nm. Using both in situ and ex situ small-angle X-ray scattering, we show that the monolayer formed on a Langmuir-Blodgett trough exhibits long-range order. Moreover, after compressing the monolayer, we found that the stress accumulated prior to the monolayer collapse triggers a transition to a short-range order not previously reported. If such monolayer is compressed further, the second layer is not formed as in the case of standard nanoparticles. Instead, a growth of islands by an odd number of layers is observed, leading to a thin film with a structure consisting of two different orientations of the hexagonal lattice. Such anomalous behavior may have implications for the possibilities of thin-film formation.

Effect of treatment time and radio frequency power on roughness and wettability of oxygen plasma-etched Cadmium Telluride thin films

The thermal evaporated Cadmium Telluride (CdTe) on Indium tin oxide substrates was etched using Oxygen plasma at various treatment times and radio frequency (RF) power. The roughness and wettability parameters were calculated using atomic force microscopy and contact angle (CA) analysis. The morphology evolution increases the interface width w and the lateral correlation length ξ with etching time and RF power. The local roughness exponent near-0.5 shows the self-affine of the surface during the etching process. The obtained experimental exponents in the present work introduce the universality class of the scaling exponents. The surface hydrophilicity of films was studied using the measurement of the two droplets CA on the film surface and the surface energy. The physical and chemical structure of the surface affected by oxygen plasma causes the surface to become more rough and hydroxyl group formation. Infra-Red spectra of the untreated and etched films using Fourier transform infrared spectroscopy confirmed the presence of the CdTe bond and a hydroxyl group. The wettability behavior of the etched films demonstrated the transition from the Cassie-Baxter state to the Wenzel state. Results show surface energy of the etched films increases, and theirs become hydrophilic.

Diffusion-Induced Ingress of Angiotensin-Converting Enzyme 2 into the Charge Conducting Path of a Pentacene Channel for Efficient Detection of SARS-CoV-2 in Saliva Samples.

Rapid and accurate identification of a pathogen is crucial for disease control and prevention of the epidemic of emerging infectious like SARS-CoV-2. However, no foolproof gold standard assay exists to date. Nucleic acid-based molecular diagnostic tests have been established for identifying COVID-19. However, viral RNAs are highly unstable in handling with poor laboratory procedures, leading to a false negative that accelerates the spread of the disease. Detection of the spike protein (S1) of the SARS-CoV-2 virus through a proper receptor, commonly used in antigen-based rapid testing kits, also suffers from false-negative predictions due to decreasing viral titers in clinical specimens. Organic field-effect transistor (OFET)-based sensors can be highly sensitive upon properly integrating receptors in the conducting channel. This work demonstrates how angiotensin-converting enzyme 2 (ACE2) molecules can be used as receptor molecules of the SARS-CoV-2 virus in the OFET platform. Integration of ACE2 molecules into pentacene grain boundaries has been studied through the statistical analysis of rough surfaces in terms of lateral correlation length and interface width. The uniform coating of ACE2 molecules has been confirmed through growth studies to achieve better ingress of the receptors into the conducting channel at the semiconductor/dielectric interface of OFETs. We have observed less than a minute detection time with 94% sensitivity, which is the highest reported value. The sensor works with a saliva sample, requiring no sample preparation or virus transfer medium. A prototype module developed for remote monitoring confirms the suitability for point-of-care (POC) application at large-scale testing in more crowded areas like airports, railway stations, shopping malls, etc.

Formation of self-organized nano-dimensional structures on InP surfaces using ion irradiation and their wettability: A study based on experimental and theoretical concepts of surface

InP surfaces are bombarded with 50 keV Ar+ ion beam at normal incidence with fluences ranging from∼2 × 1016 to 8 × 1016 ions/cm2. The formation of self-organized nanodots on Indium Phosphide (InP) are captured by Atomic Force Microscope (AFM) and Scanning Electron Microscope (SEM). Uniformity in size of dots is improved for the higher fluences and the surface becomes Indium rich with ion irradiation. Wettability studies show that the surface contact angle (CA) increases with ion irradiation and stabilizes for later fluences. The autocorrelation and height-height correlation function are applied for surface correlation and fractal nature of AFM images. Wetting properties of fractal surfaces are explored. The interface-width is found to increase with the ion fluences. The lateral correlation length is computed using auto-correlation function, while roughness exponent and the fractal dimension were estimated using height-height correlation function. Larger values of interface width indicate the larger self-organized nanodots on the surface. Fractal formations are able to capably disperse or collect mass, energy, and information over large spatial and temporal dimensions. Due to these properties, artificial fractal structures are becoming an essential and fundamental topic of study in applied research.

Microstructural evolution of asphalt induced by chloride salt erosion

A salt-eroded environment can have a significant negative impact on asphalt pavements, especially in the salt-rich regions of east and west China. This research examines the microstructural evolution of asphalt binders due to chloride salt erosion through atomic force microscopy (AFM). The morphology, roughness parameters, statistical functions, lateral correlation length (ξ), interface width (ω), and fractal dimension (Df) are used to study the asphalt surface after chloride treatment. Results from AFM show that chloride salt erosion induces the evolution of the surface local microstructure of the asphalt. The presence of chloride salts will form an unstable amorphous film soluble in water on the surface of the asphalt to wrap the bee-structure. Once the amorphous membrane is destroyed, the bee-structure is re-exposed. As the chloride salt concentration increases, the surface roughness decreases, which is manifested as a decrease in root mean square roughness (Sq). The erosion effect of chloride ions has a significant influence on the ξ and ω of the asphalt samples. The two spatial parameters ω and ξ can provide precise information about the asphalt surface texture together with Sq. Furthermore, the fractal dimension can better reflect the evolution of bee-structures with chloride salt concentration and erosion time. The study results shed light on explaining the essential role of the microstructural evolution of asphalt films which are known as chloride salt erosion.

Thickness effect on scaling law and surface properties of nano-dimensional SnTe thin films

SnTe is an important material because of its applications in mid-infrared photo-detectors. In the present work, the effects of film thickness on scaling law and surface properties (i.e., morphologies and optical properties) of SnTe thin films have been investigated. SnTe thin films of different thicknesses are prepared by means of e-beam evaporation technique. The surface morphology of each film is analyzed by atomic force microscopy (AFM) as well as a scanning electron microscope. The crystallinity of the films is found to increase with increasing film thickness, as confirmed by x-ray diffraction and Raman measurements. Fractal analysis is performed on AFM images to investigate the irregularity of surfaces. It is found that the surface of the thicker sample is rougher than the thinner sample. The autocorrelation function is applied to investigate the self-affine fractal nature of surfaces. The average roughness, interface width, lateral correlation length, local surface slope, and fractal dimension increased with film thickness. The values of roughness exponent, growth exponent, dynamic exponent, and steepening exponent are calculated and found to be α=0.76-0.96, β=0.75, z=1.92, and λ=0.35-0.25, respectively. The scaling exponents together with the other parameters such as the local surface slope indicate that the growth is quasi-3D island/mound type with rapid surface roughening behavior and obeys anomalous scaling. The multiple scattering cross sections of light together with Fourier transform infrared spectroscopy data analyses suggest that the higher crystalline film with a smaller number of defects is infrared-sensitive and may be more suitable for advanced mid-infrared detector applications.

Decoding the topographical features of more realistic SERS active substrates in presence of the probe molecules from statistical considerations: An in-depth study bridging Microscopy with Spectroscopy

This paper reports for the first time the topographical parameters of SERS active substrates, fabricated through Langmuir-Blodgett and self-assembly techniques, in presence of the probe 4- Mercapto Pyridine (4-Mpy) molecules. Prior to this study the topographical parameters of bare SERS active substrates in absence of probe molecules had been investigated. However, correlating the topographical parameters of bare SERS active substrates with the corresponding SERS responses may be incomplete and imprecise, as in reality the SERS signals are collected from the probe molecules only upon adsorption on the substrates. The adsorption of probe molecules on the SERS active substrates can modify their overall morphologies in comparison to the pristine counterparts. The present paper thus reports the topographical features of the SERS active substrates in presence of 4-Mpy molecule from the statistical considerations in terms of lateral correlation length ξ , Hurst or roughness exponents α , root mean square surface roughnesses ω and fractal dimensions D f . Attempts have been made to correlate the topographical features of the substrates in presence of 4-Mpy molecule with their corresponding SERS responses. The chaotic behaviors of the substrates in pristine form and in the presence of 4-MPy molecules are also revealed from the Lyapunov exponents and the 2D phase space trajectories. We believe that the present report will help to correlate the topographical features of more realistic SERS active substrates in presence of probe molecules with their corresponding SERS activities and render significant advancement towards successful fabrications of efficient SERS active substrates in future endeavors. • Surface topographies of the SERS active substrates have been explored in detail. • Topographical features of the substrates were mapped in presence of 4-MPy molecule. • Bare SERS substrates are compared with the same substrate in presence of 4-Mpy. • The chaotic behavior of the substrates has been revealed from Lyapunov exponents.