Structure Zone Model Research Articles

Effect of abnormally oriented grains on the ferroelectric properties of Al0.65Sc0.35N thin films

The wide bandgap wurtzite Al1-xScxN ferroelectric material is compatible with semiconductor processes and offers advantages such as high remanent polarization (Pr) and high-temperature stability. To clear the relationship between the structure zone model (SZM), abnormally oriented grains (AOGs) and the ferroelectric properties, the Al0.65Sc0.35N films were prepared at various sputtering pressures (0.32–0.90 Pa) and substrate temperatures (200–500 ℃) on low resistance n+-(111) Si substrate by the radio frequency dual-source reactive magnetron sputtering method using Al and Sc targets under pure N2 gas. The introduction of AOGs facilitates compressive stress reduction and promotes ferroelectric switching. However, excessive AOGs will damage the (002) orientation, leading to loss of ferroelectricity. The Al0.65Sc0.35N films synthesized under a sputtering pressure of 0.52 Pa and a substrate temperature of 400 ℃ exhibited a lower leakage current at high electric field, with a Pr value of 154.3 μC/cm2 and a negative coercive field (Ec-) of 3.1 MV/cm at a testing frequency of 1 kHz. The outstanding comprehensive properties support the large potential of Al1-xScxN ferroelectric material for high-performance FeRAM devices.

Influence of magnetron sputtering process parameters on the morphology of palladium thin films: An empirical study

Abstract The heightened initial energy of deposited atoms during the magnetron sputtering process alters the conventional rules of structure zone transformation for film morphology, posing challenges in fabricating Pd films with specific morphologies. This study aims to elucidate the impacts of substrate temperature and sputtering power on the morphology of Pd films and to determine the magnetron sputtering process parameters for preparing Pd films within a typical structure zone. Pd thin films were fabricated by using magnetron sputtering under varying substrate temperatures and sputtering powers. The morphologies of the films were examined through Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). With increasing substrate temperature, the structure zone of Pd films transitions from Zone T to Zone 2, and subsequently to Zone 3. Given that initial energy enhances the diffusion capability of deposited atoms, the threshold temperature for structural zone transformation of Pd films prepared by magnetron sputtering is lower than the critical value suggested by the Structure Zone Model (SZM). While sputtering power does not critically affect the structure zone of Pd films, it influences grain size and preferred orientation. The substrate temperature is the decisive factor affecting the structural zone of thin films, with the critical temperature for structure zone transformation in magnetron sputtering being lower than that proposed by the Structural Zone Model (SZM). Furthermore, the research has determined the magnetron sputtering process parameters necessary for fabricating Pd thin films with specific structure zones. This study paves the way for subsequent enhancements in the hydrogen sensitivity of palladium thin film sensors through morphology control.

Treelike PS-PVD coating: Hierarchical branching by shading and sintering

A structure zone model (SZM) with columnar structures for conventional physical vapor deposition (PVD) has been assigned to plasma spray-physical vapor deposition (PS-PVD) coatings. However, many different comprehensive properties between PS-PVD and conventional PVD coatings reveal the essential different microstructures. In this work, an impact-diffusion model was established based on the impact and diffusion behavior of depositing units. The microstructure formation of PS-PVD coatings was simulated. Results clearly display that the PS-PVD coating shows a novel treelike structure with hierarchical branches rather than a well-known columnar structure. The hierarchical branching is determined by the shadowing effect. Besides, temperature-promoting diffusion of vapor units can generate the in-situ sintering of the coatings. In-situ sintering happens during the deposition process and can govern the branching behavior. A novel treelike SZM is established as an enlargement of the conventional one, marked by successive transformations in branching and densifying. The treelike SZM is experimentally proved by the electron microscopy images and mechanical properties of typical PS-PVD YSZ coatings.

Deposition pressure-controlled phase tailoring and stability of β-W for spintronic applications

Understanding the nucleation and growth of tungsten (W) is technologically important in spin-to-charge interconversion for realizing energy-efficient spintronic devices. Here, we have systematically investigated the effect of Ar deposition pressure (PAr) on the nucleation and growth of W. The observed surface topography as a function of PAr reveals a microstructural transition from zone T to zone 1 in the structure zone model. The physical origin for the increasing roughness as a function of PAr correlates with the surface diffusion of adatoms and growth kinetics in the Volmer–Weber growth mechanism. Grazing incidence x-ray diffraction (GIXRD) results show that W exhibits a structural phase transition from a mixed phase of (α+β)-W to a single phase of β-W as a function of PAr. The analysis of the electron diffraction patterns obtained from the films grown on amorphous-SiNx windows also supports these observations. The observed transition is fundamentally correlated with the growth kinetics in zone T and zone I. Thickness-dependent GIXRD results qualitatively prove that the film grown in zone T exhibits compressive strain, whereas that grown in zone I exhibits only tensile strain. The critical thickness for the phase transition is strongly attributed to the strain during nucleation and growth. The increasing resistivity as a function of PAr corroborates the change in structural phases. Thickness-dependent resistivity measurements correlate with the degree of crystallinity via relative intensity observed from the GIXRD results. Our results strongly suggest that W structural phases can be deterministically controlled via PAr for developing low-power spintronic devices.

Residual stresses prediction in transition metal nitrides sputtered coatings using artificial neural network and experimental evaluation of surface morphology

In the production of transition metal nitride hard coatings under specific deposition conditions, the resulting residual stresses play a critical role in determining the mechanical properties, adhesion, and overall performance of the coatings. In this work, an artificial neural network (ANN) that utilizes feed-forward architecture is used to predict the average residual stress in titanium nitride (TiN) coatings with different coating thickness. These coatings are manufactured under varying bias voltages and temperature on substrate. The impact of variations in coating thickness, bias voltage, and temperature on development of internal residual stresses and changes in microstructure within sputtered coatings have been gathered from existing literature. The data collected is within the context of fibrous (zone I) and mix columnar and fibrous structure (combined zone) as defined by an existing structure zone model. The model is trained with experimental data from literature. The model is trained with experimental data from literature. The validation of the ANN model is carried out by comparing the predictions with experimental results. X-ray diffraction is used to analyze the residual stresses, preferred orientation, and the structure (zone I and combined zone) of produced coatings under different sputtering parameters. The regression and performance curves are used to assess the efficacy of ANN model. The coefficient of determination of trained model and mean square error are 0.9918 and 0.35, respectively. The predicted results show good agreement with experimental and subsequently AFM grain morphology analysis captures the growth mechanisms involved in the residual stresses evolution.

Optoelectronic properties of perovskite thin films derived from lead sulfide via radio frequency magnetron sputtering: effect of the substrate temperature

Methylammonium lead iodide (CH3NH3PbI3; MAPbI3) films were fabricated from sputtered lead sulfide (PbS) films prepared at various substrate temperatures according to the Thornton structural zone model. PbS films were converted to lead iodide (PbI2) and finally to MAPbI3 in a two-step gas-phase reaction. The increase in substrate temperature caused the morphology to change to fibrous interconnected grains, which played an important role in improving the optoelectrical properties of perovskite films. Moreover, enhanced charge transport of MAPbI3 films was observed owing to the fibrous interconnected PbI2 precursor, which was confirmed by a higher absorption coefficient and longer carrier lifetime.

Influence of deposition pressure on the microstructure and mechanical properties of sputter-deposited MoNbTaW refractory multi-principal element alloy thin films

A systematic investigation into the effects of deposition pressure on the microstructure and mechanical properties of MoNbTaW refractory multi-principal element alloy (RMPEA) films deposited on Silicon (100) substrates using direct current magnetron sputtering (DCMS) is presented. The deposition pressure was varied from 3 Pa to 0.3 Pa at a homologous temperature (T/Tm) ≤ 0.1. The crystal structure, surface morphology, cross-sectional microstructure and mechanical properties were studied using X-ray diffraction, scanning and transmission electron microscopy and nanoindentation. X-ray diffraction findings indicate a single-phase BCC structure throughout the pressure range. An evolution in surface morphology was observed, coupled with a transition from a void-rich to a densified microstructure as the deposition pressure decreased, in line with the structure zone model. Additionally, variations in crystallographic orientations were detected, with changes in I(110)/(211) suggesting an interplay between film growth dynamics and crystallographic orientation shifts with the deposition pressure. The mechanical properties have shown significant improvement, with hardness and modulus values increasing from 7GPa to 12 GPa and 135 GPa to 243 GPa, with a decrease in deposition pressure. The study provides insights into the deposition mechanism, highlighting that microstructural changes and variations in crystallographic orientations are influenced by deposition pressure-induced alterations in adatom energy and surface mobility, thus affecting the films' mechanical properties.

Towards lowering energy consumption during magnetron sputtering: Benefits of high-mass metal ion irradiation

The quest for lowering energy consumption during thin film growth by magnetron sputtering techniques becomes of particular importance in view of sustainable development goals. As large fraction of the process energy is consumed in substrate heating for the purpose of providing high adatom mobility necessary to grow dense films, the most straightforward strategy toward more environment-friendly processing is to find alternatives to thermally activated surface diffusion. One possibility is offered by high mass metal ion irradiation of the growing film surface, which has been recently shown to be very effective in densification of transition metal nitride layers grown with no external heating, such that Zone 2 microstructures of the structure-zone model are obtained in the substrate temperature Ts range otherwise typical for Zone 1 growth. The large mass difference between the incident ion and the atoms constituting the film results in effective creation of low energy recoils, which leads to film densification at low Ts. Due to their high mass, metal ions become incorporated at lattice sites beyond the near-surface region of intense recoil generation leading to further densification, while preventing the buildup of residual stress. The practical implementation of this technique discussed in this Perspective employs heavy metal targets operating in the high-power impulse magnetron sputtering (HiPIMS) mode to provide periodic metal-ion fluxes that are accelerated in the electric field of the substrate to irradiate layers deposited from direct current magnetron sputtering (DCMS) sources. A key feature of this hybrid HiPIMS/DCMS configuration is the substrate bias that is synchronized with heavy metal ion fluxes for selective control of their energy and momentum. As a consequence, the major fraction of process energy is used at sputtering sources and for film densification, rather than for heating of the entire vacuum vessel. Model material systems include TiN and metastable NaCl-structure Ti1−yAlyN films, which are well-known for challenges in stoichiometry and phase stability control, respectively, and are of high relevance for industrial applications. This Perspective provides a comprehensive overview of the novel film growth method. After presenting basic concepts, time-resolved measurements of ion fluxes at the substrate plane, essential for selective control of metal ion energy and momentum, are discussed. The role of metal ion mass, energy, momentum, and concentration is described in more detail. As some applications require substrate rotation for conformal coating, a section is devoted to the related complexity in the implementation of metal-ion-synchronized growth under industrial conditions.

Numerical Investigation of Asphalt Concrete Fracture Based on Heterogeneous Structure and Cohesive Zone Model

The fracture behavior of asphalt concrete is closely related to its internal structure. A deep understanding of the relationship between the internal structure and fracture behavior of asphalt concrete is very important for sustainable and durable pavement design. In this paper, a CZM-based FE model was developed to investigate the fracture behavior of asphalt concrete. An image-aided approach was used to generate the 3-D internal heterogeneous structure of asphalt concrete. A series of 2-D cross sections were extracted from the 3-D structure for finite element modeling. Then numerical simulations of SCB tests were conducted and validated with experimental results. With the validated CZM-based FE model, the effects of some critical factors, including temperature, loading rate, aggregate geometry, fracture strength, and fracture energy, on the fracture behavior of asphalt concrete were investigated. The analysis results showed that the average damage of the adhesive elements was higher than that of the cohesive elements at the peak load. At lower temperatures, asphalt concrete tends to crack earlier, and the cracking path tends to be marginally closer to the aggregates. A higher loading rate may induce more, but minor, element damage since the CZM elements in asphalt mortar cannot bear much more stress through deformation. Angular aggregates may induce a higher percentage of damaged elements, especially adhesive-damaged elements. On average, each 10% increase in fracture energy allows the specimen to bear 2.31% more load and 2.82% more displacement. Sufficient fracture energy could improve the ability of asphalt concrete to resist fracture.

Investigation of Optical Properties and Electronic Transfer of Temperature-Dependent ZnO Nanocolumnars Grown by DC Sputtering

The morphology of zinc oxide (ZnO) can determine the distribution of defects in the system, which plays an important role in determining its optical and electronic properties. Here, we investigate the optical and electronic transfer properties of different ZnO surface morphologies. ZnO nanocolumnar was synthesized by direct-current (DC) sputtering followed by annealing using a ratio of T / Tm are 0.15, 0.20, and 0.25. The x-ray diffraction (XRD) results show that an increase in annealing temperature causes an increase in crystal size accompanied by a decrease in lattice strain. Furthermore, the surface morphology of the sample changed with increasing annealing temperature treatment, following the structural zone model. The optical and electronic transfer properties of the samples were investigated in three regions; region 1 ( T / Tm is 0.15), region 2 ( T / Tm is 0.20), and region 3 ( T / Tm is 0.25) using optical modeling. The highest surface electronic transfer was noted in region 2, which is indicated by the highest surface energy loss function (SELF). This research can provide a good understanding in designing optoelectronic systems based on their morphological features. DOI: 10.17977/um024v7i22022p086

Magnetron sputtered NiAl/TiBx multilayer thin films

Transition metal diboride-based thin films are currently receiving strong interest in fundamental and applied research. Multilayer thin films based on transition metal diborides are, however, not yet explored in detail. This study presents results on the constitution and microstructure of multilayer thin films composed of TiBx and the intermetallic compound NiAl. Single layer NiAl and TiBx and NiAl/TiBx multilayer thin films with a variation of the individual layer thickness and bilayer period were deposited by D.C. and R.F. magnetron sputtering on silicon substrates. The impact of the operation mode of the sputtering targets on the microstructure of the thin films was investigated by detailed compositional and structural characterization. The NiAl single layer thin films showed an operation mode-dependent growth in a polycrystalline B2 CsCl structure with a cubic lattice with and without preferred orientation. The TiBx single layer thin films exhibited an operation mode independent crystalline structure with a hexagonal lattice and a pronounced (001) texture. These TiBx layers were significantly Ti-deficient and showed B-excess, resulting in stoichiometry in the range TiB2.64–TiB2.72. Both thin film materials were deposited in a regime corresponding with zone 1 or zone T in the structure zone model of Thornton. Transmission electron microscopy studies revealed, however, very homogeneous, dense thin-film microstructures, as well as the existence of dislocation lines in both materials. In the multilayer stacks with various microscale and nanoscale designs, the TiBx layers grew in a similar microstructure with (001) texture, while the NiAl layers were polycrystalline without preferred orientation in microscale design and tended to grow polycrystalline with (211) preferred orientation in nanoscale designs. The dislocation densities at the NiAl/TiBx phase boundaries changed with the multilayer design, suggesting more smooth interfaces for multilayers with microscale design and more disturbed, strained interfaces in multilayers with nanoscale design. In conclusion, the volume fraction of the two-layer materials, their grain size and crystalline structure, and the nature of the interfaces have an impact on the dislocation density and ability to form dislocations in these NiAl/TiBx-based multilayer structures.

Growth condition effects on the structure evolution and electrical properties of low-melting-point bismuth films

Based on the growth conditions, an expanded structural zone model (SZM) is proposed for polycrystalline low-melting semimetal Bi films.

On the grain size-thickness correlation for thin films

A meta-analysis of published data in combination with measurements on Al, Cu, CuO, CoCrCuFeNi, Ni90Cr10, TiN, and V sputter deposited thin films, demonstrates that the grain size is correlated to the film thickness by a power law. The growth exponent depends on the homologous temperature which is defined as the ratio between the deposition and the melting temperature of the studied material. An average value of the growth exponent close to 0.4 was found for the growth exponent for a homologous temperature between 0.14 and 0.31. Film growth models that depict an evolutionary overgrowth mechanism obtain the same growth exponent. Above a homologous temperature of approximately 0.3, a slightly higher exponent is observed which agrees with the general idea that at higher homologous temperatures the grain size is also influenced by restructuring mechanisms occurring during film growth. At low homologous temperatures (<0.14), a substantially lower exponent was noticed. From a theoretical point of view the growth exponent’s value should be close to zero. The aforementioned boundaries of the homologous temperatures correspond with those observed in published structure zone models that describe the microstructure of physical vapor deposited thin films. The good agreement suggests that the underlying mechanism for the observed boundaries is the atom mobility. This hypothesis was further investigated by a study on the influence of intentionally added impurities on the power law behavior for Al and Cu thin films. For both materials, a similar decrease of the grain size as a function of an increasing impurity-to-metal impingement flux ratio on the substrate was observed. No change of the growth exponent is observed for Al, while the growth exponent becomes almost zero for Cu at sufficiently high impurity-to-metal flux ratios.

Tunable hydrophilicity in a surface nano-textured stainless steel thin film deposited by DC magnetron sputtering

In this article a series of Stainless steel thin films are fabricated by DC power magnetron sputtering of a SUS316 stainless steel target at various argon working pressure. The sample film compositions retain that of an austenitic stainless steel, while XRD spectra reveal that all films possess a single phase, body-centered cubic ferrite crystal structure. At working pressure 6 mTorr and above, the film exhibits a textured surface morphology made up of nano-sized pyramids. Cross-sectional images show that increasing argon pressure cause a microstructural evolution from dense, fibrous grain to coarse tapered grains. This observation agrees with the prediction by Thornton's structural zone model and causes a drastic reduction in static water contact angle (WCA) from ~65° to ~17°. With further increase of argon pressure, a minimum WCA of 11° at 8 mTorr can be achieved. In addition, our textured film deposited at 12 mTorr exhibits both excellent hydrophilicity and low contact angle hysteresis (CAH) at the same time. In summary, this work reports a convenient way of depositing a stainless steel-like hydrophilic coating, in which the wetting properties are tunable via working pressure control.

Role of sputter powers and deposition temperatures towards the growth of nc‐W2N/a‐Si3N4 nanocomposite coating

AbstractIn physical vapour deposition (PVD) processes, deposition parameters such as pressure, power, temperature, etc. are extremely important for process control and coating performance. Among these target power and substrate temperature (Tsub) play a critical role in defining phase, morphology, adhesion, etc. Optimized parameters are very much required for their best performance, deviating from these will affect its performance and quality. Although relevant but they are the less attended parameters. In this work, two series of samples were prepared by varying (i) silicon nitride (Si3N4) target power (50, 75, 90 and 110 W); and (ii) substrate temperatures (200°C–450°C). Their role in the formation and evolution of microstructural and mechanical properties was studied for nc‐W2N/a‐Si3N4 nanocomposite coatings (nc: nano crystalline, a: amorphous). All the coatings were prepared by reactive magnetron sputtering. In the first series, the mechanical performance of nc‐W2N/a‐Si3N4 coatings, prepared by varying Si3N4 target power was compared with pure W2N. It has been shown that coating performance strongly depends on Si3N4 target power. The coating shows maximum enhancement of mechanical properties at 50 W Si3N4 target power. The 50 W can be selected as optimized power for the preparation of nc‐W2N/a‐Si3N4 nanocomposite coatings. In the case of the second series of samples, the role of substrate temperature in different parameters was measured/ calculated and compared. All properties show a strong dependency on Tsub. Field emission scanning electron microscope, shows modification in surface and internal (cross‐section) microstructure of coating on varying Tsub and on mechanical properties. Experimentally observed hardness‐microstructure relationship is in good agreement with theoretical Structure Zone Model (SZM). The above results confirm that excellent quality nc‐W2N/a‐Si3N4 coating can be prepared through magnetron sputtering at 400°C and 50 W of Si3N4 power. These results clearly show the importance of processing parameters for depositing a good quality of coating with excellent properties. These results will help the coating industries to improve their product performance.

Experimental evaluation of the role of oxygen on the growth of MgOx nano-sculpted thin films synthesized by reactive magnetron sputtering combined with glancing angle deposition

In this work, we have studied the influence of oxygen on the chemistry and morphology of nano-sculpted MgOx thin films prepared by magnetron sputtering in glancing angle configuration. First, we have studied the poisoning mechanism of the Mg target by² combining target voltage and deposition rate measurements with chemical analysis of the deposited films by X-ray Photoelectron Spectroscopy. The results reveal a strong metal-to-compound transition at very low oxygen flows, namely < 5% of O2 in the gas mixture. This transition is accompanied by a dramatic decrease of the deposition rate (by 95%) and by the synthesis of fully oxidized films. Then, for thee gaseous mixtures corresponding to the metallic conditions as well as to the edges of the metal-to-compound transition, namely 0%, 2.5% and 5% of O2 in the gas mixture, nano-sculpted films have been grown. From SEM images, it appears that even a slight amount of O2 in the gas mixture strongly affects the morphological features of the films by reducing the width of the tilted columns (by 50% for 2.5% of O2) as well as the intercolumnar space (by 85% for 2.5% of O2). This has been understood by considering the growth mechanism of thin films in reactive conditions and the Structural Zone Model associated with these conditions.

Grain Structure and Electrical Properties of Transparent Indium Oxide Thin Films Prepared by RF Magnetron Sputtering

Transparent conductive films of indium oxide (In2O3) are deposited on a glass substrate by RF magnetron sputtering and their electrical properties are investigated in relation to their microstructure. Sputtering deposition was carried out with variations of normalized substrate temperature (Ts/Tm where Tm is the melting temperature) and argon partial pressure (PAr). At a very low substrate temperature (Ts/Tm &lt; 0.1), the columnar grains with voided grain boundaries are observed in the In2O3 films, which are attributed to the low surface mobility and atomic shadowing effect. With an increase in the substrate temperature, tight grain boundaries are formed between the growing columnar grains. At high temperature (0.3 &lt; Ts/Tm &lt; 0.5), the grain surface is faceted, which is due to the high surface mobility of the sputtered atoms, and development of preferred orientation with grain growth is promoted. The growing morphology is also dependent on the argon partial pressure. At low PAr deposition, an inclined fibrous grain oriented to the target direction and a smooth surface structure is developed. As the PAr increases, a dome-shaped surface structure and columnar grains normal to the substrate are developed due to the scattering effect of the sputtered atoms. The growing morphology with substrate temperature and argon pressure coincides with the Thornton's Structure Zone Model (SZM). The lowest electrical resistivity (2.1×10-2 Ωcm) is observed in the In2O3 films with tight grain boundaries and faceted grains, which corresponds to zone II region of the SZM.

Influence of overstoichiometric boron and titanium addition on the properties of RF magnetron sputtered tungsten borides

In this work, (W,Ti)B2 films with different stoichiometric ratio Ti/W deposited on silicon and 304 stainless steel by radio frequency magnetron sputtering are presented. The coatings were deposited from plasma spark sintered targets obtained from the mixture of pure boron, tungsten and titanium powders. It is shown that during plasma spark sintering process using overstoichiometric boron and a low content of titanium change the WB2 to WB4 phase with almost no secondary phases. Subsequently, the impact of titanium content on the films properties is investigated systematically, including the chemical and phase composition, crystalline structure, surface and cross-section morphology. Simultaneously, nano-indentation test and ball-on-disk tribometery are performed to analyse the hardness and tribological properties of the films. It is shown that deposited films with titanium content of 3.6 and 5.5 at.% are formed in the zone T of the Thornton's Structural Zone Model. In opposite to α-WB2 magnetron sputtered coatings they are more flexible and hard nanocomposite coatings. The results show that the addition of titanium is apparently changing the film structure from nanocrystalline columnar to amorphous, very dense and compact structure with the addition of TiB2 phase. That films are simultaneously hard (H > 37.5 GPa), have high hardness to effective Young's modulus ratio values (H/E⁎ > 0.1) and elastic recovery (We > 60%) appropriate for tough and resistant to cracking materials. The presented (W,Ti)B2 films exhibit also tribological and corrosion properties better than unalloyed coatings.

Investigation of growth characteristics and semimetal-semiconductor transition of polycrystalline bis-muth thin films.

The preferred orientation growth characteristics and surface roughness of polycrystalline bis-muth (Bi) thin films fabricated on glass substrates using the molecular beam epitaxy method were investigated at temperatures ranging from 18 to 150°C. The crystallization and morphology were analyzed in detail and the polycrystalline metal film structure-zone model (SZM) was modified to fit the polycrystalline Bi thin film. The boundary temperature between Zone T and Zone II in the SZM shifted to higher temperatures with the increase in film thickness or the decrease of growth rate. Furthermore, the effect of the thickness and surface roughness on the transport properties was investigated, especially for Bi thin films in Zone II. A two-transport channels model was adopted to reveal the influence of the film thickness on the competition between the metallic surface states and the semiconducting bulk states, which is consistent with the results of Bi single-crystal films. Therefore, the polycrystalline Bi thin films are expected to replace the single-crystal films in the application of spintronic devices.

Investigation of the Fatigue Behaviour of a Ballastless Slab Track–Bridge Structural System under Train Load

To probe into the time-dependent behaviour of the ballastless track–bridge structural system under train load, based on the import of the static and fatigue damage constitutive model of materials to simulate damage deterioration of the structural system and interface cohesive zone model to the interface layer, a three-dimensional nonlinear finite element model of the China Railway Track System Type II (CRTS II) ballastless track–bridge structural system was established using the equivalent static method. Then, using this model, we developed the numerical simulation analysis of the influence law of material damage deterioration on structural system performance under train load and revealed the fatigue evolution of the structural system. The results show that the beam remains in compressed status for the whole process, the track is in compression in the midspan and in tension at the beam end, and the tensile stress is larger near the shear groove under the double-track static load. Under the fatigue load, stiffness degradation of the structural system is not obvious, and integral rigidity of the structural system is dependent on the rigidity of the beam. Strength reduction of the materials caused stress redistribution of the structural system and had a larger effect on the stress of each layer of track structure than on the stress on the beam. The fatigue degradation of the cement-emulsified asphalt (CA) mortar layer material has a significant impact on the structural system, which directly affects structural layer stress variation with the fatigue loading cycle.