KMC Simulation Of Nanostructured Thin Film Growth And Its SERS Performance

Surface enhanced Raman scattering(SERS)is a versatile non-destructive and molecular recognition technology,which is widely used in various fields such as the analysis of chemical substances,trace detection.SERS performance is mainly affected by the surface morphology and material of SERS substrate,thus,exploring and designing nanostructured SERS substrate is the primary goal of SERS researches.Currently,the investigations on the SERS substrates is mainly through batch experiments.In actual practice,not only the process parameters during fabrication are very complicated and difficult to finely control the morphology of SERS substrates,batch experiment itself is a long and tedious process.Therefore,a joint of Kinetic Monte Carlo(KMC)simulation,COMSOL finite element analysis and verification experiment method were conducted to investigate the morphology and SERS performance of film SERS substrate.The main work is drawn as below.(1)The growth process and nanostructures of Ag film under various deposition parameters with e-beam evaporation method were simulated using the KMC method in NASCAM.The influence of different deposition angles,temperatures and rates on the film growth process,film morphology,film roughness and density were investigated.The relationship between deposition angle and the film morphology,roughness and density;the influence of deposition temperature on the film growth process,the diameters of the nanocolumn and the film roughness;and the influence of deposition rate on the film growth process and separation distance of nanocolumn were got from the simulation results.It was found that the deposition angle is the most significant factor that affect the morphology and nanostructure of the film.(2)Based on a series nanostructured film with various morphology obtained from KMC result.Approximated nanostructure models were carried out and the local enhanced electrical field of nanostructured film was simulated and calculated in COMSOL as well as SERS enhancement factor.It was got the local enhanced electric field and SERS performance of the Ag film with nanocolumnar and non-nanocolumnar structure,different nanocolumn diameters and different nanocolumn separation.It indicates that the film nanocolumnar structure is the most significant factor that affect the nanostructured film SERS performance.(3)Ag films were fabricated under various deposition angle with e-beam evaporation method to verify the KMC simulation result and COMSOL simulation result.The morphology,roughness and SERS performance of films were characterized and then compared with KMC and COMSOL simulation results.