Fuzzy Interface System for the Prediction of Optical Properties of ZnO Thin Film

Abstract

A fuzzy logic approach is widely used in predicting and controlling the process parameters. This paper presents FIS for the prediction of optical properties of aqueous ZnO thin film prepared by spray pyrolysis method. The impact of various process parameters such as precursor concentration, solution flow rate, substrate temperature and annealing temperature on transmittance and band-gap have been considered. FIS modeling and simulation carried out in Matlab using fuzzy logic toolbox. The results obtained from simulation shows good agreement with experimental results. It can predict 95.46% accurate transmittance and 99.45% accurate bandgap values.

Introduction

I. INTRODUCTION

ZnO is highly transparent semiconductor material with wide band-gap energy. It has tremendous applications in optoelectronic devices and sensor technology. The thin films of oxides can be synthesized by various methods. The most common techniques used for preparation of thin films are Silar, CBD, CVD, electro-spinning, electrodeposition, spray pyrolysis, etc. [1].

The spray pyrolysis technique is most widely used to deposit thin films. Physiochemical properties of deposited film are greatly affected due to process parameters [2]. Therefore, to achieve the desire requirements of physiochemical properties one must know about the precise values of process parameters. Generally, researchers decide it by performing literature review and further performing experiments again and again. Hence it is time consuming as well as expensive too. Fuzzy logic simulation approach provides better solution for it [3]. It provides predictive model for the thin film properties [4].

II. MATERIAL AND METHODS

Zinc oxide thin films were deposited on glass substrate by using aqueous solution of Zinc acetate dehydrate, with the help of spray pyrolysis technique. The effect of various process parameters such as precursor concentration, spray rate, substrate temperature and annealing temperature on optical properties i.e., transmittance and band-gap were evaluated. Further, obtained experimental data was used to design fuzzy interface system for the prediction of transmittance and band-gap of ZnO thin film deposited by spray pyrolysis technique. The details of FIS are represented in this paper.

A. Designing of Fuzzy Interface System

The fuzzy interface system model was designed using Matlab fuzzy logic toolbox. Mamdani fuzzy interface model was most widely used due to its accuracy and rules that based upon linguistic variables [5]. Hence in this work also Mamdani fuzzy interface model was used to design the system. The optical properties such as transmittance and band-gap are significantly depending upon input process parameters of spray system, which include precursor concentration, substrate temperature, solution flow rate and annealing temperature. The structure of FIS is as shown in figure 1 given bellow. This figure 1 clearly indicate that inputs are get ANDed together to give desired output of fuzzy interface system.

C. Fuzzy Rules

A set of 22 rules have been defined with the help of actual experimental data. These rules are defined as bellow.

1. If (Concentration is VL) and (Substrate_Temp is M) and (Flow_rate is M) and (Annealing_Temp is M) then (Transmittance is VVH)(Bandgap is VVH) (1)
2. If (Concentration is VH) and (Substrate_Temp is M) and (Flow_rate is M) and (Annealing_Temp is M) then (Transmittance is M)(Bandgap is M) (1)
3. If (Concentration is M) and (Substrate_Temp is H) and (Flow_rate is M) and (Annealing_Temp is H) then (Transmittance is VVH)(Bandgap is VH) (1)
4. If (Concentration is M) and (Substrate_Temp is H) and (Flow_rate is M) and (Annealing_Temp is VH) then (Transmittance is VVH)(Bandgap is VH) (1)
5. If (Concentration is M) and (Substrate_Temp is H) and (Flow_rate is M) and (Annealing_Temp is VVH) then (Transmittance is VVH)(Bandgap is VH) (1)
6. If (Concentration is L) and (Substrate_Temp is M) and (Flow_rate is M) and (Annealing_Temp is M) then (Transmittance is VH)(Bandgap is VH) (1)
7. If (Concentration is M) and (Substrate_Temp is M) and (Flow_rate is M) and (Annealing_Temp is M) then (Transmittance is H)(Bandgap is VH) (1)
8. If (Concentration is H) and (Substrate_Temp is M) and (Flow_rate is M) and (Annealing_Temp is M) then (Transmittance is M)(Bandgap is M) (1)
9. If (Concentration is VVH) and (Substrate_Temp is M) and (Flow_rate is M) and (Annealing_Temp is M) then (Transmittance is L)(Bandgap is L) (1)
10. If (Concentration is M) and (Substrate_Temp is VL) and (Flow_rate is M) and (Annealing_Temp is M) then (Transmittance is VL)(Bandgap is VH) (1)
11. If (Concentration is M) and (Substrate_Temp is L) and (Flow_rate is M) and (Annealing_Temp is M) then (Transmittance is L)(Bandgap is VH) (1)
12. If (Concentration is M) and (Substrate_Temp is H) and (Flow_rate is M) and (Annealing_Temp is M) then (Transmittance is VH)(Bandgap is VH) (1)
13. If (Concentration is M) and (Substrate_Temp is VH) and (Flow_rate is M) and (Annealing_Temp is M) then (Transmittance is VH)(Bandgap is VH) (1)
14. If (Concentration is M) and (Substrate_Temp is VVH) and (Flow_rate is M) and (Annealing_Temp is M) then (Transmittance is VVH)(Bandgap is VH) (1)
15. If (Concentration is M) and (Substrate_Temp is VVH) and (Flow_rate is VL) and (Annealing_Temp is M) then (Transmittance is VVH)(Bandgap is VVH) (1)
16. If (Concentration is M) and (Substrate_Temp is VVH) and (Flow_rate is L) and (Annealing_Temp is M) then (Transmittance is VVH)(Bandgap is VVH) (1)
17. If (Concentration is M) and (Substrate_Temp is VVH) and (Flow_rate is M) and (Annealing_Temp is M) then (Transmittance is VVH)(Bandgap is VVH) (1)
18. If (Concentration is M) and (Substrate_Temp is VVH) and (Flow_rate is H) and (Annealing_Temp is M) then (Transmittance is VVH)(Bandgap is VVH) (1)
19. If (Concentration is M) and (Substrate_Temp is VVH) and (Flow_rate is VH) and (Annealing_Temp is M) then (Transmittance is VVH)(Bandgap is VVH) (1)
20. If (Concentration is M) and (Substrate_Temp is VVH) and (Flow_rate is VVH) and (Annealing_Temp is M) then (Transmittance is VVH)(Bandgap is VVH) (1)
21. If (Concentration is M) and (Substrate_Temp is H) and (Flow_rate is M) and (Annealing_Temp is VL) then (Transmittance is L)(Bandgap is H) (1)
22. If (Concentration is M) and (Substrate_Temp is H) and (Flow_rate is M) and (Annealing_Temp is L) then (Transmittance is VH)(Bandgap is H) (1)

D. Defuzzification

It is the process of converting fuzzy inputs to the crisp output [6, 7].

Different kind of defuzzifyng methods are available some of them are centroid, Mean-Max Membership, Centre of Sums, Centre of Largest Area, Weighted Average Method. To achieve the accuracy of fuzzy reasoning model selection of defuzzification method plays vital role. The ‘centre of area’ method is widely used due to its more accurate and precise results as compared to other methods. Therefore in this work centre of area method was employed [8, 9].

IV. ACKNOWLEDGMENT

The Authors are thankful for Rayat Institute of Research and Development for supporting this work.

Conclusion

A fuzzy logic model for the prediction of transmittance and bandgap of aqueous ZnO thin film deposited via spray pyrolysis technique was successfully designed with Matlab fuzzy logic toolbox. The effect of process parameters on optical properties i.e. transmittance and bandgap was investigated by performing actual experiments. Triangular membership functions were defined for input and output. Fuzzy logic rule base has been constructed by using experimental data which shows the relation between input attributes i.e. precursor concentration, substrate temperature, solution flow rate and annealing temperature with output attributes transmittance and bandgap. For defuzzification ‘Centroid Area Method’ was implemented. The FIS was tested with four data sets of experiments and it shows good agreement with actual experimental data. The prediction results obtained for transmittance of ZnO film shows 95.46% accuracy and that of for bandgap shows 99.45% accuracy. Hence, the fuzzy logic approach can provide cost effective solution for the thin film synthesis with desire optical properties.

References

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Copyright

Copyright © 2023 Nikam S. V., B. T. Jadhav, S. M. Chiwate, G. S. Nhivekar. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.