tech-2023_01(106)

№ 1 (106) январь, 2023 г. ABSTRACT The main goal of the research was to study the dependence of current on voltage, temperature dependence of current, and the influence of conductivity on light of (medium thickness alloyed with iodine solution in 8% alcohol and mercerized with NaOH) The grade \"Komolot-79\" cotton fibers (CF) with semiconducting properties. The study was conducted in the temperature range (296-360 K) and voltage range (0-100 V). The sample doped with iodine is much higher than the undoped sample current was observed. It was observed that the current flowing through the sample fully obeyed Ohm's law. The value of the deep surface activation energy obtained as a result of introducing iodine into the cotton fiber was determined. It has been experimentally established that the electrical conductivity of iodine-doped cotton fibers grade \"Komolot-79\" increases with increasing temperature according to the law σ = σ exp (- Еt / kТ), where Еt = 0,74 eV. АННОТАЦИЯ Основной целью исследований было изучение зависимости тока от напряжения, температурной зависимости тока и влияния электропроводности на свет (средняя толщина легирована раствором йода в 8% спирте и мерсеризо- вана NaOH). Сорта «Комолот-79» хлопковые волокна (ХВ) с полупроводниковыми свойствами. Исследование проводилось в диапазоне температур (296-360 К) и диапазона напряжений (0-100 В). В образце, легированном йодом, ток намного выше, чем в нелегированном образце. Было замечено, что ток, протекающий через образец, полностью подчиняется закону Ома. Определено значение глубокой поверхностной энергии активации, полученной в результате введения йода в хлопковое волокно. Экспериментально установлено, что электропровод- ность легированных йодом хлопковых волокон марки «Комолот-79» увеличивается с повышением температуры по закону σ = σ exp (-Еt/kТ), где Еt = 0,74 эВ . Keywords: cotton fibers, natural semiconductors, doping, photoconductivity, electrical conductivity, current-voltage characteristic, activation energy. Ключевые слова: xлопок волокон, природные полупроводники, легирование, фотопроводимость, электро- проводность, вольт-амперная характеристика, энергия активации. ________________________________________________________________________________________________ Introduction After washing, the CF was kept in a bath with the solution 20% NaOH in water at 15℃ for 2 minutes. After The success of modern electronic technology is di- removing the CF from the bath, excess NaOH that has rectly related to the development of fine technology for not formed a chemical bond is completely washed off the production of semiconductor materials of germa- with water and samples are dried under standard condi- nium, gallium arsenide, silicon, etc., and the production tions[6]. Then CF cut sides were soaked in 8% alcohol of various devices based on them. At present, almost all solution of iodine and diffused at t=800C for 7 hours. properties of the above semiconductors have been iden- In order to create an ohmic contact and seal the cold tified. To expand the possibilities of semiconductor de- from the external environment, we have developed an vices, it is necessary to identify and explore new electrically conductive adhesive based on graphite and semiconductor materials[1]. liquid glass. Crushed finely granular graphite moved with liquid glass to a thick state. After that, such an elec- Recently, the promising scientific direction \"Natural trically conductive adhesive (R=300 Ohm at a thickness semiconductors\" has begun to develop intensively [2]. of 20 µm and a length of 0.4 sm) was applied to the Research carried out in recent years has shown that cotton end sides. This made it possible to obtain reproducible fibers (CF) have semiconductor properties, their electri- results, measurements. Thus, the samples were made cal conductivity increases with increasing temperature. in the form of a bundle of fibers, in the amount of 5000-6500 pieces laid parallel to each other, with a total When doping CF with iodine, the conductivity in- weight of 4-15 mg. The current-voltage characteristics creases by several orders of magnitude and is sensitive of the fabricated samples are linear. Preliminary meas- to light. Experiments show that the electrophysical prop- urements showed that after doping with iodine, the sam- erties of CF depend on the grade of CF. This mainly ap- ples had n-type conductivity. plies to the superficial area of the CF - the cuticle. Apparently, the cuticles of different varieties of CF dif- Material and Methods fer from each other. At present, the electrophysical prop- erties of CF grades ATM-1, Gulbahor, Golib, Diyor The temperature dependences of the electrical con- doped with iodine have been studied [3–5]. However, ductivity of natural fibers were measured using a contact the electrophysical properties of \"Komolot-79\" grade thermometer and a special heat chamber. The installa- CF alloyed with iodine have not been studied. Expand- tion allows current measurement in the temperature ing the scope of research in this area makes it possible range of 20 - 800С. (Fig.1). to identify the physical patterns occurring in natural semiconductor materials and create various discrete With increasing temperature, the electrical conductiv- semiconductor devices based on them. ity of the semiconductor increases exponentially σ = σ0 exp (-E/kT). If there are donor or acceptor impurities The object of the study were mature CF varieties in the semiconductor, at the temperature of absolute \"Komolot-79\". In order to dope the CF with iodine, first zero there will not be a single free electron (or hole) in the CF with the seed was carefully combed with a fine the impurity semiconductor. As the temperature rises, comb (with a point period of 0.5 mm), then the seeds were cut out from the side. 20

№ 1 (106) январь, 2023 г. impurity electrons will be the first to be released, since is much less than the activation energy of semiconductor the activation energy of an impurity (donor or acceptor) atoms. 1 - contact mercury thermometer, 2 – sample, 3 - heat chamber, 4 – heater, 5 – nanoammeter, 6 - power supply. Figure 1. Electrical circuit for measuring the temperature dependence of the electrical conductivity of natural fibers A further increase in temperature leads to the fact Results and Discussion that the impurity atoms are ionized, and only then does the intrinsic electrical conductivity of the semiconductor We have studied the temperature dependences of the appear. Consequently, at low temperatures, the electrical electrical conductivity in samples of the \"Komolot-79\" conductivity of an extrinsic semiconductor is determined grade CF doped with iodine. In the temperature range by the extrinsic conductivity, and at high temperatures, +20÷800C, the electrical conductivity grows exponen- by its intrinsic conductivity. The larger the band gap Eg, tially with the activation energy En =0.74 eV. This is ap- the more energy an electron must have in order to jump parently due to the fact that iodine in the \"Komolot-79\" into the conduction band, i.e. the higher the temperature variety form deep level with Et= Ec –0.74 eV. At high the semiconductor must be heated to make its own con- temperatures in cold water, destruction can occur. If we ductivity noticeable. assume that the width of the band gap CF is Eg=3.2 eV, then obviously at these temperatures we cannot measure the dependence σ=f(T) in the intrinsic conduction region. Figure 2. Temperature dependence of electrical conductivity of a sample of \"Komolot-79\" grade CF alloyed with iodine At t=80℃ for 7 hours, Arrhenius diagram of this result 21

№ 1 (106) январь, 2023 г. Figure 2 shows the volt-amper characteristic (VAC) Measurement of the kinetics of the phase transition of the \"Komolot-79\" grade CF doped with iodine when illuminated with UV light with hν≈5 eV showed 1-undoped sample (0.2 nA at 100 V), 2 - A sample that the growth of the photocurrent occurs according doped with iodine is in the dark, 3 - sample doped with to an exponential law with a time constant τ=656 sec. iodine under UV light. It can be seen from the figures It decreases as the intensity of UV light increases. After that the VAC has a linear character. turning off the light, the decrease in photoconductivity occurs more slowly than the exponential law. Figure 3. VAC CF grade \"Komolot-79\" at T = 300K, 1-undoped sample (0.2 nA at 100 V), 2 - A sample doped with iodine is in the dark, 3 - sample doped with iodine under UV light Conclusion A sharp increase in the conductivity of iodine-doped CF is the concentration of charge carriers in CF related According to the conclusion, the electrophysical to the increase. Input molecules are located in the defects properties of undoped and iodine-doped \"Komolot-79\" of the polymer lattice and creates a deep layer in the for- cotton fiber were studied. According to the analysis of bidden band, resulting in free charge carriers. This en- experimental results, the electrical conductivity in- sures conductivity even at room temperature. creased by more than 1000 times when doped to the grade \"Komolot-79\" CF mercerized with NaOH. This Thus, for the first time, the electrophysical proper- result means that it is possible to control the conductance ties of cotton fibers of the \"Komolot-79\" grade doped by doped an input to the CF. with iodine were studied. It has been established that io- dine in the \"Komolot-79\" grade CF creates deep level with ionization energy Еn = 0.74 eV. References: 1. Gurusiddayya Hiremath, Mallesh N and Sunil Kumar B. A Comparative Study on Different Semiconductor Materials used for Power Devices and Its Applications. International Journal of Latest Technology in Engineering, Manage- ment & Applied Science (IJLTEMAS) Volume VII, Issue I, January 2018. 2. A.T. Mamadalimov, P.K. Khabibullaev, M. Shermatov. Some problems of modifying the physical properties of cotton fibers. UFJ, 1999 v.1. No. 6, pp. 465-479. 3. Mamadalimov A.T., Oksegendler B.L., Otazhjnov Sh.O., Turaev B.E., Usmanov T.A., Khakimova N.K., and KadIrov Zh.A. Features of the Photoconductivity of Iodine-Doped Cotton Fibers Illuminated in the Fundamental Absorption Range. Technical Physics Letters, 2002. Vol. 28, No. 7, pp.581-583 4. A.T. Mamadalimov A new scientific direction in semiconductor physics: natural semiconductors. “Trends in the development of modern semiconductor physics: problems, achievements and prospects”. Collection of materials of the international online conference. www.e-science.uz May 28, 2020 , from 16-25. 5. N.K. Khakimova. Properties of natural semiconductor fibers. Tashkent. “KALEON PRESS”, 2021, 112 p. 6. Francis J Kolpak Mark Weih John Blackwell. Mercerization of cellulose: Determination of the structure of Mercerized cotton. Polymer Volume 19, Issue 2, February 1978, Pages 123-131. https://doi.org/10.1016/0032-3861(78)90027-7. 22

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Научный журнал UNIVERSUM: ТЕХНИЧЕСКИЕ НАУКИ № 1(106) Январь 2023 Часть 5 Свидетельство о регистрации СМИ: ЭЛ № ФС 77 – 54434 от 17.06.2013 Издательство «МЦНО» 123098, г. Москва, улица Маршала Василевского, дом 5, корпус 1, к. 74 E-mail: [email protected] www.7universum.com Отпечатано в полном соответствии с качеством предоставленного оригинал-макета в типографии «Allprint» 630004, г. Новосибирск, Вокзальная магистраль, 3 16+