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an innovative application of deep barrier silicon structures for sensory devices with photoelectrical transformation has been suggested. The principal possibility of the photovoltaic transducer implementation for identification of metallic and semiconductor single-wall carbon nanotubes covered with surfactant in water solution was analyzed in detail. The obtained results are qualitatively explained by local electrostatic influence on the parameters of recombination centers at the silicon surface. This influence can be associated with the dipole moment of molecules absorbed at the surface of the nanotube from surfactant sodium dodecylbenzene sulfonate (SDBS). Moreover, the spatial configuration of charged fragments near the defects at the silicon surface can occur. Another possible reason for carbon nanotubes identification is due to the different polarizability of metallic and semiconductor nanotubes. These results are explained in the frame of Stevenson-Keyes's theory. The reported effect can be further applied as the basis for the control and selection of carbon nanotubes with different conductivity types.

We identified different nano-carbon species such as graphene nanoplatelets, graphite flakes and carbon nanotubes dispersed in N-methyl-2-pyrrolidone using a novel sensor structure based on a “deep” silicon barrier working as a photoelectrical transducer. Each nano-carbon particle has specific signature in both 2D photocurrent distribution and photocurrent dependencies on bias changing surface band-bending. Additionally, all nano-carbon particles have characteristic features in the time-dependent evolution of photocurrent. The obtained results can be explained by the influence of nano-carbon molecules' local electric field on the recombination parameters of defect centers on the silicon surface.

The development of hardware and software for remote control systems can effectively resolve these problems. The article discusses the main steps of modeling analog and digital parts of power supplies and technical solutions for laboratory work in Multisim and Proteus. The important task of developing remotely controlled power supplies based on microcontrollers for research purposes is discussed in detail. Development is carried out by modeling the developed schemes based on digital and analog elements. The algorithm of work and the basic stages of designing the electronic circuit and methods of stabilization with the application of the microcontroller are described in detail. Software application for remote control of the power supply in real-time has been developed. The possibility of conducting remote real experiments in the courses of semiconductor electronics and peripherals was demonstrated.

The basic principles of finite-state machine synthesis and simulation on Proteus CAD and VHDL are discussed. The main steps of designing an electronic circuit of the control and operating finite-state machines that perform the calculation of a given algebraic expression were described. The main steps of consistent performance of a complex task for the development of cross-cutting knowledge and skills, which must be performed by the student in the framework of the normative discipline ware analysed in detail. It is shown that the developed cycle of laboratory works can be successfully implemented in various training courses.

A capability to produce effective sensor structures on the basis of “deep”silicon junction has been substantiated. If the incident light is strongly absorbed by this junction, the photocurrent through it is shown to substantially depend on the recombination characteristics and the charge state of the illuminated surface, provided that the junction parameters are optimal. The depth of the illuminated region is demonstrated to exceed the diffusion length of minority charge carriers. It is found that the larger diffusion length of minority charge carriers corresponds to stronger changes of the photocurrent generated by the illuminated surface area. A possibility to transform the junction from a photodetector into an effective chemical sensor is verified by numerical calculations. The physical mechanisms relating the changes in the effective surface recombination rate and the absorption of polar molecules are discussed. The sensor properties of suggested silicon junctions are analyzed for a number of analytes. Their suitability for the creation of selective chemical sensors (electronic noses) is demonstrated experimentally., В роботi обґрунтовано можливiсть використання кремнiєвого переходу для ефективних сенсорних структур. Показано, що в умовах опромiнення свiтлом з областi сильного поглинання фотострум суттєво залежить вiд рекомбiнацiйних характеристик та зарядового стану поверхнi у випадку оптимальних параметрiв переходу. Визначено, що товщина освiтлюваної областi для такої структури повинна перевищувати довжину дифузiї неосновних носiїв заряду. Визначено також, що бiльшiй довжинi дифузiї вiдповiдають бiльшi змiни фотоструму при адсорбцiї на робочiй поверхнi. З використанням числового моделювання проаналiзовано можливiсть змiни областi застосування переходу вiд фотоперетворювача до сенсорної структури при певному виборi його параметрiв. Обговорено фiзичнi механiзми, якi можуть пов’язувати змiни ефективної швидкостi iз процесами адсорбцiї полярних молекул. Cенсорнi властивостi запропонованих структур дослiджено для декiлькох аналiтiв. Експериментально продемонстровано придатнiсть такої структури для створення хiмiчних сенсорiв, якi мають функцiю селективностi та пiдтримують концепцiю електронного носу.

A concept of new photovoltaic transducer, combining properties of planar p–n solar cell and light-addressable potentiometric sensor (LAPS) is considered for chemical sensor application. The proposed photovoltaic transducer operation principle based on change of surface recombination velocity during gas adsorption. As compared with typical LAPS, the considered sensor has no reference electrode, it is not necessary to apply DC bias voltage and such sensor is applicable not only for liquid but for gas detection also. The influence of p–n junction depth, doping level, diffusion length on photocurrent of planar silicon junction for different value of surface recombination is studied by numerical simulation. It allows optimizing the junction parameters from point of view of its efficient application as a chemical sensor with photovoltaic transducer. The proposed chemical sensor concept was verified by LBIC method on modified industrial solar cell.

The insertion of a thin amorphized layer (AL) in the space charge region of a silicon solar cell is proposed as a way to improve the conversion efficiency due to the impurity photovoltaic effect. Previously, this approach had been applied to a cell with a layer inserted in the emitter by the ion implantation. The insertion of such layer in the space charge region is founded to be preferable, because a better control over the recombination (via energy levels in the band gap and local states of interfaces) can be achieved. The parameters of a modified device are investigated by the numerical simulation, and it is concluded that the layer parameters have a crucial influence on the cell conversion efficiency. Based on our simulation results, the optimal AL and the height of barriers are determined. In such a case, the short circuit current density is improved due to the absorption of photons with energy less than a silicon band gap of 1.12 eV in AL, whereas the open circuit voltage and fill factor remain unchanged. Theoretically, the increase in the efficiency by 1–2% is achievable. In the non-optimal case, the degradation of a short circuit current and the fill factor eliminate the positive effect of an additional photogeneration in AL., Створення тонкого субмiкронного аморфiзованого шару (АШ) в областi просторового заряду кремнiєвого фотоперетворювача може збiльшувати коефiцiєнт корисної дiї за рахунок домiшкового фотоелектричного ефекту. Ранiше цей пiдхiд був застосований до структур з модифiкованим шаром в областi емiтера. Такий шар можна створити за допомогою iонної iмплантацiї. Вбудова шару в область просторового заряду є перспективним пiдходом, оскiльки дозволяє досягти зменшення впливу рекомбiнацiї (через енергетичнi рiвнi в забороненiй зонi та рiвнi, пов’язанi iз локальними станами iнтерфейсiв). Параметри фотоперетворення модифiкованої структури дослiджено методом чисельного моделювання, який дозволяє отримати свiтловi вольт-ампернi характеристики для рiзних параметрiв АШ. На пiдставi цих результатiв визначено оптимальнi параметри АШ. У такому випадку щiльнiсть струму короткого замикання збiльшується завдяки поглинанню фотонiв з енергiєю, меншою нiж ширина забороненої зони кремнiю 1,12 еВ, а напруга холостого ходу та фактор заповнення залишаються майже без змiн. Теоретично, можливо отримати, пiдвищення ефективностi на 1–2% за абсолютною величиною. Це можливо, якщо шар з бар’єром у валентнiй зонi (менше, нiж 0,4 еВ) та бар’єром у зонi провiдностi (менше, нiж 0,1 еВ) створено у площинi, яка вiдповiдає близько 0,3 ширини областi простору заряду. У iншому випадку деградацiя струму короткого замикання i фактора заповнення нiвелює позитивний ефект додаткової фотогенерацiї. Збiльшення напруги холостого ходу на 10–12% (внаслiдок обмеження iнжекцiї в p-базу) супроводжується суттєвою деградацiєю щiльностi струму короткого замикання. Так, для збiльшення напруги холостого ходу шар iз суттєвим потенцiальним бар’єром в зонi провiдностi (близько 0,4 еВ) повинен бути розташованим поблизу базової областi.

Recently, porous silicon has demonstrated the attractive physical properties which offer a potential to design antireflection coatings for solar cells [1,2,3], light emitting diodes [4], for generating of metal impurities [5], as electro- and thermoinsulating material and other applications. It is also considered a material for gas sensors due to its adsorptional ability, strong dependence of luminescence, and conductivity on the gas ambient. In spite of such advantages of the material, it has not yet been applied widely for the gas sensing perhaps because the nature of the adsorption mechanisms has not been studied enough.

The problem of silicon substrate selection for the sensor structure based on deep junction barrier has been investigated. The described sensor is functioning on photoelectrical conversion principle for the illumination with has high absorption coefficient in the silicon. The method of substrate pre-selection with the measurement of capacitance-voltage characteristics has been suggested. As shape of the capacitance-voltage curves in the system liquid analyte/silicon substrate (with or without chemically modified silicon surface) highly depends on charge state of the interface and near-surface band bending, some recommendation for silicon substrate choosing can be used. The obtained results indicate that the shift of the saturation voltage of the capacitance-voltage curves correlates with peculiarities of photocurrent distribution in the deep silicon barrier structure. Based on the results of the research the effective recombination sensors with reproducible characteristics can be fabricated.