Effect of n and p-silicon Substrate on Dielectric Constant, Dielectric Loss Tangent of PPy-MWCNTs/TiO2/Al2O3 Structure

Synthesized these novel structures PPy-MWCNTs/TiO2/Al2O3/p-Si and PPy-MWCNTs/TiO2/Al2O3/n- for using in manufactures diodes, sensor, supercapacitors, and electronic devices. The effect of silicon substrate type on electrical and dielectric parameters such as dielectric constant ɛ`, dielectric loss tangent tanδ, Cole –Cole diagram, the width of the depletion layer (Wd), barrier height (Φb), density state of surface (NSS) and series resistance (Rs) of Au/PPy-MWCNTs/TiO2/Al2O3 were discussed in this work. Researchers frequently alter the composite ratio to increase dielectric characteristics; however, in this study, we use a different approach by altering the type of substrate to improve the dielectric and electric properties of the structure. The sign and magnitude of ɛ` and tanδ are affected by the type of silicon substrate, for example, at frequency 2 × 107 Hz, ɛ` for structure on p-Si has both positive and negative value range (-3500 to 200), whereas ɛ` for structure on n-Si exclusively has negative values (-280 to -220). On the other hand, at the same frequency, tanδ has both positive and negative values (-2 to 8) for structure on p-Si, whilst for n-Si has positive values (0.78 to 0.83). At f = 107 Hz, ɛ` has positive values ranging from (0 to 900) for p-Si substrate while for n-Si, ɛ` has both positive and negative values (-500 to 1500).

As seen in Fig. 5(a-a`) at V =-2 V, ɛ` have negative values at high and low frequencies for both cases, whereas at mid frequencies, ɛ` has positive values up to 9000 as seen in figure a, which represents p-type silicon substrate, on the other hand, ɛ` has values up to 5500 as seen in figure a`, which represent n-type silicon. These findings show that the structure on the p silicon substrate has a higher dielectric constant than that on n silicon. At voltage equal -1 V, ɛ` has negative values at high and low frequencies for both structures, though at mid frequencies have positive values as seen in Fig. 4(b-b`). In the case of PPy-MWCNTs/TiO2/ Al2O3/p-Si structure, ɛ` reaches a value of 37,000, which is higher than 14,400 in the case of PPy-MWCNTs/TiO2/ Al2O3/n-Si. At voltages of (0,1 2) V, the ɛ` have the same behavior with the values of 37,000, 18,000, 16,000 in case of PPy-MWCNTs/TiO2/Al2O3/p-Si structure while it takes the following values 25,000, 17,500, 15,000 for PPy-MWCNTs/ TiO2/Al2O3/n-Si structure as seen in figures (c-c`,d-d`,ee`). At low frequencies, the polarity of the electric dipoles is at its highest, and as the frequency rises, the dipoles no longer track the external electric field, and the electric field begins to cover the dipoles behindhand. Henceforth, the polarity of the constituents is affected and converts minimum at the greater frequencies. Figure 5 displays that the value of the dielectric constant and dielectric loss tangent Also, the thermally stimulated scattering of charge carriers and the existence of oxygen vacancies are the chief motives for the decline in ɛ` value at a lesser frequency for extreme measured temperature [36][37][38][39][40][41]. it is significant to rise the dielectric constant of the interfacial layer (ϵ'). In this mode, by means of a high dielectric interfacial thin film, the value of capacitance of metal-oxide-semiconductor capacitor can be significantly improved and it can be used in a varied range of charges/energy imprisonment and storing requests. The usage of great dielectric interfacial thin film does not lone stop inter-diffusion amid semiconductor and metal, it too eases the electric field discount subject in these devices. The dielectric constant ϵ' dependent on frequency of the structure PPy-MWCNTs/TiO2/Al2O3/p-Si for various temperatures and voltages. The value of ϵ' was found to be a strong function of frequency and voltage. This dispersion in the ϵ' values at low frequencies was attributed to the surface states localized at interfacial layer/semiconductor and surface polarization. On the other hand, this dispersion was attributed to the series resistance (Rs) and existence of oxygen vacancies. Figure 6(a, b, c, d, e) shows the dependency of ɛ` and ɛ`` for the structure of PPy-MWCNTs/TiO2/Al2O3/p-Si at various temperatures and voltages, with inset figures of (a`,b`,c`,d`,I) for PPy-MWCNTs/TiO2/Al2O3/n-Si structure. The relation between ɛ` versus ɛ``is recognized as the Nyquist plot, when comparing the structure on the p-Si substrate to that of the n-Si substrate, the semicircles are bigger, cover a larger area, and are more uniformity. With increasing temperature, the midpoint of the semicircular curve moved closer to the origin as temperature increased. It demonstrates that the structure experiences a temporal relaxation phenomenon. The point of connection of the semicircular curve on the actual axis of the complex plane provides an approximation of grain resistance, grain boundary capacitance, grain boundary, and grain capacitance and resistance. Usually, the interference at the low and high frequencies of real impedance provides the approximate value of grain resistance and grain boundary resistance, respectively [42]. Figure 7(a, b, c, d, e) shows the dependency of ɛ` and ɛ`` for the structure of PPy-MWCNTs/TiO2/Al2O3/p-Si at various temperatures and voltages, with inset figures of (a`,b`,c`,d`,I) for PPy-MWCNTs/TiO2/Al2O3/n-Si structure. As displayed in all figures at all voltages. The semicircles of the structure on the p-Si substrate are regular. The area under semicircles is big, the radius increases with rising temperatures except at V = 2 V, whereas in the structure of PPy-MWCNTs/TiO2/Al2O3/n -Si. The semicircles are not regular. the area under the semicircles is seen as small, and the radius increase with increasing temperatures except at V = 2 V. In Fig. 5(c-c``, d-d`, e-e`) both two structures on p and n-Si substrate have the same behavior. The semicircles increase with temperatures increase. The semicircular curves are determined by the relaxation power. The fact that the area or radius of the semicircles decreases with increasing temperature indicates that the temperature is dependent on the relaxation process [43]. The values of Wd, Φb(C-V), and NSS are strongly dependent on frequency due to the quality of the interfacial PPy-MWCNTs/TiO2/Al2O3 layer, Nss, and Rs. The capacitance-voltage and G/w-V characteristics are influenced by the regularity of barrier height and interfacial layer width between metal and semiconductors. As shown in Fig. 8(a-a', b-b'), the Wd values in the structure of PPy-MWCNTs/TiO2/Al2O3/p-Si grow as the frequency increases, however, the Wd values in the structure of PPy-MWCNTs/TiO2/Al2O3/n-Si increase as the frequency decreases.
In Fig. 9(c-c`), the barrier height in both structures increases at low frequency, however, the barrier height in PPy-MWCNTs/TiO2/Al2O3/p-Si decreases significantly more than in PPy-MWCNTs/TiO2/Al2O3/n-Si. As shown in Fig. 9(d`), the barrier height decrease at low and mid frequencies while it increases in the high frequencies, on the other hand, the barrier height raises at low and mid frequencies, but at high frequencies, it decreases for the structure of PPy-MWCNTs/TiO2/Al2O3/p-Si as in Fig. 9(d). Figure 10 illustrates increase the width of the depletion layer and barrier height with frequency at low frequency for two structure on n and p silicon substrates, whilst at mid and high frequency the Wd increase slightly for structure on n-Si, and decrease for structure on p-silicon, but the barrier height decrease on n and p silicon. In Fig. 11. NSS is frequency independent in the structure on the p-Si substrate, however, it increases at low frequencies, whereas the series resistance Rs rises at low frequencies, Fig. 6 (a, b, c, d, e) Fig. 7 (a, b, c, d,  In the structure on the n-Si substrate, both NSS and Rs values rise in low frequencies, whereas NSS rises in mid and high frequencies, whereas Rs remains frequency-independent as seen in Fig. 11. The Na and barrier height behave similarly in both structures, the barrier height in the PPy-MWCNTs/ TiO2/Al2O3/p-Si structure decreases significantly more than in the PPy-MWCNTs/TiO2/Al2O3/n-Si structure, as shown in Fig. 12. All values data for electric parameters Wd, φ b , Nss, Na listed in Table 1 and Table 2 4 Conclusion Synthesized these novel structures PPy-MWCNTs/ TiO2/Al2O3/p-Si and PPy-MWCNTs/TiO2/Al2O3/nfor using in manufactures diodes, sensor, supercapacitors, and electronic devices.The work presented a comprehensive study on the effect of silicon substrate type on the electrical and dielectric parameters of the PPy-MWCNTs/TiO2/Al2O3 structure. The dielectric parameters such as dielectric constant ɛ`, dielectric loss tangent tanδ, Cole -Cole diagram, the width of the depletion layer Wd, barrier height Φb, density state of surface Nss and series resistance Rs have been investigated for Au/PPy-MWCNTs/TiO2/Al2O3 structure deposited on n and p silicon substrates. The sign and value of ɛ` and tanδ are affected by the type of silicon substrate, for example, at frequency 2 × 107 Hz, ɛ` for structure on p-Si has both positive and negative value range (-3500 to 200), whereas ɛ` for structure on n-Si exclusively has negative values (-280 to -220). On the other hand, at the same frequency, tanδ has both positive and negative values (-2 to 8) for structure on p-Si, whilst for n-Si has positive values (0.78 to 0.83). At f = 107 Hz, ɛ` has positive values ranging from (0 to 900) for p-Si substrate while for n-Si, ɛ` has both positive and negative values (-500 to 1500). Other variations of ɛ` and tan δ, as well as Wd, Φb, Rs, and Nss with the variation of the substrate, were explored in detail through the manuscript. Data Availability Data availability statement (also sometimes called a 'data access statement') tells the reader where the research data associated with a paper is available, and under what conditions the data can be accessed. They also include links (where applicable) to the data set.

Declarations
Ethics Approval By obtaining ethical approval the researcher is demonstrating that they have adhered to the accepted ethical standards of a genuine research study. Participants have the right to know who has access to their data and what is being done with it.
Consent to Participate I understand that all information I provide for this study will be treated confidentially.
Consent for Publication I voluntarily agree to take part in this study. I understand I will receive a copy of this consent form. I understand that

Conflicts of Interest/Competing Interests
The authors declare that they have no conflict of interest or competing interests.
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http:// creat iveco mmons. org/ licen ses/ by/4. 0/.