The main object of this thesis is the diagnostics of the diaphragm discharge generated in water solutions containing supporting electrolytes (mostly NaCl), and description of particular processes before and after discharge breakdown by DC non-pulsed voltage up to 2 kV. Although many applications of electric discharge in liquids have been developed during the last years, the exact mechanism of the discharge ignition is not sufficiently known up to now. Based on this reason, this work is focused on the investigation of processes before the discharge ignition, breakdown parameters and the discharge itself both in the irregular and stable regime. The theoretical part of the work presents proposed mechanisms of the discharge generation in water solutions including the description of particular kinds of known discharges. Diaphragm discharge is one of many possible configurations of electrical discharges in liquids. In fact, electrical discharge in water forms non-thermal plasma, which is generated by high voltage, and many physical and chemical processes are started in plasma channels (so-called streamers). Among physical processes, high electrical field, shock waves and last but not least emission of electromagnetic radiation in visible and ultra-violet radiation belongs. The most important chemical processes are generation of various active species as hydrogen peroxide, and OH radical. Three batch plasma reactors using a diaphragm configuration with different total volume (4 l, 100 ml and 50 ml) are employed in the presented work. The discharge is created in an orifice (a pin-hole) in the dielectric barrier separating two electrode parts of the reactor. DC non-pulsed high voltage up to 4 kV is used for the discharge generation. Electrodes are made of stainless steel or platinum, and they are installed in parallel to the diaphragm in a variable distance from the dielectric barrier in each reactor part. The dielectric barrier is made of PET or Shapal-MTM ceramics with the variable thickness (0.2?2 mm). One pin hole st the diaphragm center with diameter of 0.2?1.5 mm are used in contemporary experiments. Time resolved characteristics of current and voltage are recorded using four-channel oscilloscope which detected their output values. Parameters are measured by the constantly increasing DC voltage with a step of 100 V. The solutions containing sodium chloride electrolyte are used at five different conductivities. Recorded time resolved characteristics determine breakdown moment, and describe current and voltage in particular parts within the static current-voltage curve. The breakdown appeared at lower applied voltage when the electrode distance is enhanced. However, the electrode distances higher than 4 cm does not induce any significant change of the breakdown voltage. The influence of pin-hole diameter is less obvious in the studied range, but a slight enhancement of breakdown voltage is observed with the increasing pin-hole diameter. Current-voltage characteristic curve moves towards lower voltage with the diaphragm thickness enhancement. The work compares the influence of conductivity change on current-voltage characteristics as well as the effect of inorganic salt kind. By the conductivity enhancement, the measured current-voltage curve moves towards lower voltage which means that the breakdown voltage is decreased. Sizes of the reactors do not have any effect on the processes before and after discharge breakdown.

Cette thèse est une contribution aux développements de HEMTS AlGaN/GaN sur substrat de silicium pour des applications basses fréquences sous fortes tensions (typiquement 600V) comme les commutateurs pour la domotique ou les circuits de puissance des véhicules électriques. Elle a été menée en collaboration étroite avec Picogiga International qui a réalisé toutes les épitaxies. Elle est composée de trois parties : développement d'une technologie de fabrication, étude des courants de fuite, amélioration du pouvoir isolant de la barrière et recherche d'un comportement “normally off”. La réalisation de contacts ohmiques peu résistifs est l’étape cruciale de la fabrication des HEMTs AlGaN/GaN de puissance. Une optimisation de l'empilement des métaux utilisés, de la température et du temps de recuit ainsi que la recherche d'un compromis sur la distance métallisation – gaz d'électrons, nous a permis de réaliser des contacts ohmiques proches de l'état de l'art (0,5 Ohm.mm). L’origine des courants de fuite a été systématiquement étudiée sur cinq types d'épitaxies différentes. La distance grille – drain et les courants de fuites ont été identifiés comme étant les deux facteurs limitant la tension de claquage. Selon la structure, les courants de fuite ont lieu soit à travers la grille (~e-8 A/mm à 210V), soit en parallèle au canal (e-5 A/mm). Dans les deux cas, ces courants sont comparables aux courants de fuite au travers du tampon (i.e. courants mesurés entre deux mésas). Ces courants de fuite, ont été attribués aux couches de transition nécessaires à l'adaptation de l'épitaxie des couches de nitrure sur le substrat de silicium. La réalisation de HEMT AlGaN/GaN sur silicium pour les applications à haute tension passera donc par une amélioration de ces couches tampons.Nous avons démontré qu'il est possible d'améliorer l'isolation de la barrière en AlGaN grâce à une hydrogénation du matériau. En effet un traitement de surface des transistors par un plasma hydrogène permet, par diffusion, d'y incorporer de l'hydrogène qui passive les dislocations traversantes. Après traitement, les courants de fuite de grille sont réduits et la tension de claquage est repoussée à 400V avec des courants de fuite de l'ordre de e-6 A/mm. Dans ces conditions, le claquage a alors lieu en surface de l'échantillon, il n'est plus limité que par la distance grille-drain. Ce résultat ouvre la voie à la réalisation de HEMT à forte tension de claquage (V~600V).L’effet du plasma fluoré SF6 sur les caractéristiques électriques des HEMT (AlN/GaN)/GaN (la barrière est en super-réseaux AlN/GaN) a été étudié pour la première fois dans cette thèse. Les ions fluor incorporés dans cette barrière agissent comme des donneurs qui font augmenter la densité du gaz bi-dimensionnel d'électrons et décaler la tension de pincement vers les tensions négatives. Cet effet est à l'opposé de celui observé dans les HEMT à barrière en AlGaN. Ce résultat élimine la possibilité de réaliser les HEMT (AlN/GaN)/GaN “normally off” par un dopage au fluor, une technique simple et efficace qui donne de bons résultats sur les HEMT à barrière AlGaN. D’autre part, il apporte quelques réponses expérimentales aux prévisions théoriques d'utiliser le fluor pour les dopages de type n ou p dans les nitrures d'éléments III. / This thesis is a contribution to the development of AlGaN/GaN HEMTs on silicon substrates for low frequency and applications under high voltages (typically 600V) as switches for home automation or power circuits of electric vehicles. It was conducted in close collaboration with Picogiga who made all epitaxy. It is composed of three parts: development of manufacturing technology, study of leakage currents, improving the insulating barrier and search behavior “normally”.The realization of low resistivity ohmic contacts is the crucial step in the manufacture of AlGaN / GaN HEMTs power. Optimization of the stack of metal used, the temperature and annealing time and the search for a compromise on the distance metallization - electron gas, has allowed us to achieve ohmic contacts around the state s (0.5 Ohm. mm).The origin of the leakage current has been systematically studied in five different kinds epitaxy. The distance gate - drain and leakage currents were both identified as being factors limiting the breakdown voltage. According to the structure, the leakage currents take place either through the grid (~ e-8 A/mm at 210V), or in parallel to the channel (e-5A/mm). In both cases, these currents are comparable to leakage currents through the buffer (ie current measured between two mesas). These leakage currents were attributed to transition layers required for the adaptation of the epitaxial nitride layers on the silicon substrate. Achieving AlGaN HEMT / GaN on silicon for high voltage applications pass through to an improvement in these buffer layers.We have demonstrated that it is possible to improve the insulation of the AlGaN barrier through hydrogenation of the material. In effect a surface treatment by a hydrogen plasma allows, by diffusion, to incorporate hydrogen which passivates the through dislocations. After treatment, the gate leakage current is reduced and the breakdown voltage of 400V is pushed with leakage currents of the order e-6A/mm. Under these conditions, when the breakdown occurs at the surface of the sample, is no longer limited by the gate-drain distance. This result opens the way for the realization of HEMT with high breakdown voltage (V ~ 600V).The effect of plasma fluorinated SF6 on the electrical characteristics of the HEMT (AlN/GaN)/GaN (barrier is AlN/GaN superlattices) was studied for the first time in this thesis. The fluorine ions incorporated in the barrier act as donors that increase the density of the two-dimensional gas of electrons and the shifting to the voltage clamping negative voltages. This effect is opposite to that observed in the HEMT in AlGaN barrier. This result eliminates the possibility of the HEMT (AlN/GaN)/GaN "normally off" by fluorine doping, a simple and effective technique that gives good results on AlGaN HEMT barrier. On the other hand, it brings some experimental answers to theoretical predictions using fluorine doping for n-type or p in III nitrides.

This work investigates the fundamental device limits related to operational voltage constraints and linearity in state-of-the-art silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) in order to support the design of robust next-generation high-frequency transceivers. This objective requires a broad understanding of how much "usable" voltage exists compared to conventionally defined breakdown voltage specifications, so the role of avalanche-induced current-crowding (or "pinch-in") effects on transistor performance and reliability are carefully studied. Also, the effects of intermodulation distortion are examined at the transistor-level for new and better understanding of the limits and trade-offs associated with achieving enhanced dynamic range and linearity performance on existing and future SiGe HBT technology platforms. Based on these investigations, circuits designed for superior dynamic range performance are presented.

The Square Kilometre Array (SKA) is a multibillion and a multinational science project to build the world’s largest and most sensitive radio telescope. For a very large field of view, the combined collecting area would be one square kilometre (or 1, 000, 000 square metre) and spread over more than 3,000 km wide which will require a massive count of antennas (thousands). Each of the antennas contains hundreds of low noise amplifier (LNA) circuits. The antenna arrays are divided into low, medium and high operational frequencies and located at different positions to boost up the telescope’s scanning sensitivity.The objective of this work was to develop and fabricate fully on-chip LNA circuits to meet the stringent requirements for the mid-frequency array from 0.4 GHz to 1.4 GHz of the SKA radio astronomy telescope using Monolithic Microwave Integrated Circuit technology (MMIC). Due to the number of LNA reaching figures of millions, the fabricated circuits were designed with the consideration for low cost fabrication and high reliability in the receiver chain. Therefore, a relaxed optical lithography with Lg = 1 µm was adopted for a high yield fabrication process.Towards the fulfilment of the device’s low noise characteristics, a large number of device designs, fabrication and characterisation of InGaAs/InAlAs/InP pHEMTs were undertaken. These include optimisations at each critical fabrication steps. The device’s high breakdown and very low gate leakage characteristics were further improved by a combination of judicious epitaxial growth and manipulation of materials’ energy gaps. An attempt to increase the device breakdown voltage was also employed by incorporating Field Plate structure at the gate terminal. This yielded the devices with improvements in the breakdown voltage up to 15 V and very low gate leakage of 1 µA/mm, in addition to high transconductance (gm) characteristic. Fully integrated double stage LNA had measured NF varying from 1.2 dB to 1.6 dB from 0.4 GHz to 1.4 GHz, compared with a slightly lower NF obtained from simulation (0.8 dB to 1.1 dB) across the same frequency band.These are amongst the attractive device properties for the implementation of a fully on-chip MMIC LNA circuits demonstrated in this work. The lower circuit’s low noise characteristic has been demonstrated using large gate width geometry pHEMTs, where the system’s noise resistance (Rn) has successfully reduced to a few ohms. The work reported here should facilitate the successful implementation of rugged low noise amplifiers as required by SKA receivers.

The content of this thesis is the validation of the method of dynamic testing of solar photovoltaic cells. Testing methods for determining the parameters of the photovoltaic cell replacement scheme has been verified through testing a set of crystalline silicon photovoltaic cells. To accelerate the diffusion capacity measurement and to improve reproducibility of the measurement we propose new method of determining the time constant for diffusion capacitance using a combination of two short pulses. For this method of measurement new scheme for dynamic tester timing has been proposed and implemented.

The continuous increase of the voltage levels in power transmission systems has lead to the occurrence of higher switching transients during their operation. The design of equipment and grid components able to sustain such a stressful operation, requires an intensive study of the electric field stress generated by these transients, and their distribution to the vicinity of each configuration. Sphere-plane gaps are the most theoretically and practically interesting electrode configurations. So far, the majority of the conducted work is referred to the study of the discharge characteristics of this structure. However, a study of the electrostatic electric field is required. An accurate calculation of the electric field can contribute significantly to an even better understanding of the discharge characteristics and the principles behind them. In this project, is presented a simulation approach for the calculation of the electro-static field of a sphere-plane configuration, varying the dimensions of the sphere and the gap distance. For this purpose, a Finite Element Method (FEM) solver was used, in which the configuration was designed and the numerical solution of the problem was implemented. After that, an attempt was performed to specify the breakdown voltage based on the electric field calculation and distribution. Useful results were recorded from both the simulation of the electrostatic model and the calculation of the breakdown voltage. One of the most important findings, was the specification of an approximate relation between the diameters of the sphere and the tube where this is mounted. As a consequence, the study of the electric field distribution became easier, while at the same time an accurate calculation of the breakdown voltage was achieved. A series of validations were performed, through the comparison with the already ex-isting, published and unpublished, experimental tests and a number of conclusions were listed. One of the most significant, was the specification of the correlation between the electrostatic model and test measurements and how these different approaches can be linked to each other in a practically efficient way. At the end, there is a proposal for further work on the subject, and possible improvements of the already conducted work. / Ökningen av spänningsnivåerna i kraftöverföringssystem har lett till högre kop-plingstransienter under drift. Konstruktionen av utrustning och nätverkskomponen-ter som kan motstå en sådan påkänning, kräver en noggrann förstudie av de elektriska fältet som genereras av dessa transienter. Ett gap av sfär-platta är den mest teoretiskt och praktiskt intressanta elektrodkon-figurationen att studera. Hittills har majoritetet av genomfört arbete avsett att studera urladdningsegenskaper för denna struktur. Dock krävs studie av elektrostatiska elek-triska fältet. En noggrann beräkning av elektriska fältet kan bidra till en ännu bättre förståelse för urladdningsegenskaper och principerna bakom dem. I detta projekt presenteras en simuleringsmetod för beräkning av elektrostatiska fäl-tet av en sfär-plan konfiguration, med varierande dimensioner av sfären och gapavstån-det. För detta ändamål har använts en Finite Element Method (FEM) lösning, där kon-figurationen utformades och problemets numeriska lösningen genomfördes. Därefter har gjorts ett försök för att ange genombrottsspänningen baserad på beräkning och distribution av elektriskta fältet. Resultat registrerades från både simulering av elektrostatiska modellen och beräkn-ing av genomslagsspänningen. Ett av de viktigaste resultaten var specifikationen av ett ungefärligt förhållande mellan diametrarna av sfären och röret där sfären är monterad. Som en konsekvens blev studiet av elektriska fältfördelningen lättare, medan en exakt beräkning av genomslagsspänningen uppnåddes. En valideringsserie har genomförts genom jämförelse med de redan existerande, publicerade och opublicerade, experimentella tester och ett antal slutsatser har noterats. En av de mest meningsfulla, var specifikation av sambandet mellan den elektrostatiska modellen och provmätningarna samt hur dessa olika tillvägagångssätt kan kopplas till varandra på ett praktiskt och effektivt sätt. Slutligen finns det ett förslag för fortsatta arbete samt eventuella förbättringar av redan genomfört arbete.

<div>Power semiconductor devices play an important role in many areas, including household</div><div>appliances, electric vehicles, high speed trains, electric power stations, and renewable energy</div><div>conversion. In the modern era, silicon based devices have dominated the semiconductor</div><div>market, including power electronics, because of their low cost and high performance. The</div><div>applications of devices rated 600 V - 6.5 kV are still dominated by silicon devices, but they</div><div>are nearly reaching fundamental material limits. New wide band gap materials such as silicon</div><div>carbide (SiC) offer significant performance improvements due to superior material properties</div><div>for such applications in and beyond this voltage range. 4H-SiC is a strong candidate</div><div>among other wide band gap materials because of its high critical electric field, high thermal</div><div>conductivity, compatibility with silicon processing techniques, and the availability of high</div><div>quality conductive substrates.</div><div>Vertical DMOSFETs and insulated gate bipolar transistors (IGBT) are key devices for</div><div>high voltage applications. High blocking voltages require thick drift regions with very light</div><div>doping, leading to specific on-resistance (R_ON,SP ) that increases with the square of blocking</div><div>voltage (V_BR). In theory, superjunction drift regions could provide a solution because of a</div><div>linear dependence of R_ON,SP on V_BR when charge balance between the pillars is achieved</div><div>through extremely tight process control. In this thesis, we have concluded that superjunction</div><div>devices inevitably have at least some level of charge imbalance which leads to a quadratic</div><div>relationship between V_BR and R_ON,SP . We then proposed an optimization methodology to</div><div>achieve improved performance in the presence of this inevitable imbalance.</div><div>On the other hand, an IGBT combines the benefits of a conductivity modulated drift</div><div>region for significantly reduced specific on-resistance with the voltage controlled input of a</div><div>MOSFET. Silicon carbide n-channel IGBTs would have lower conduction losses than equivalent</div><div>DMOSFETs beyond 6.5 kV, but traditionally have not been feasible below 15 kV. This</div><div>is due to the fact that the n+ substrate must be removed to access the p+ collector of the</div><div>IGBT, and devices below 15 kV have drift layers too thin to be mechanically self-supporting.</div><div>In this thesis, we have demonstrated the world’s first functional 10 kV class n-IGBT with</div><div>a waffle substrate through simulation, process development, fabrication and characterization.</div><div><div>The waffle substrate would provide the required mechanical support for this class of devices.</div><div>The fabricated IGBT has exhibited a differential R_ON,SP of 160 mohm</div><div>.cm², less than half of</div><div>what would be expected without conductivity modulation. An extensive fabrication process</div><div>development for integrating a waffle substrate into an active IGBT structure is described</div><div>in this thesis. This process enables an entirely new class of moderate voltage SiC IGBTs,</div><div>opening up new applications for SiC power devices.</div></div>

The thesis focuses on designing and characterizing SiC 3.3 kV Diffused Metal-Oxide Semiconductor Field-Effect Transistor (DMOSFET)s with a Ron that is significantly lower than that of current commercial devices. The On-state resistance and breakdown voltage are then adjusted by adding a Super-Junction structure. Because of the pillar structure below the p-base area, the depletion will occur both vertically and horizontally and keeps the electric field distribution throughout the drift layer constant. The Super Junction Metal-Oxide Semiconductor Field-Effect Transistor (SJ MOSFET) has a good advantage compared to DMOSFETs. Due to its capacity to tolerate higher breakdown voltages and the fact that it does not require an increase in cell pitch to reach higher voltages, the Super-Junction approach is now the subject of effective research as compared to IGBTs and DMOSFETs. Silicon Carbide , a material with a wide bandgap that facilitates high temperature operation, high blocking voltage, high current flow and high switching frequency, is used to construct the device. In order to maintain a consistent electric field throughout the device, the concentration of the n and p pillars was chosen with a good charge balance between them. The outcomes of designing and simulating a DMOSFET, a Semi-SJ MOSFET, and a Full SJ MOSFET are compared in this research. The semi SJ device resulted in a Ron of 18.4 mΩcm2 and a Vb of 4.1 kV. The full SJ device reached a Ron of 12.4 mΩcm2 and a breakdown voltage of 4.2 kV. One optimized device was chosen from the semi SJ devices and used in several TCAD simulations, and the outcomes were evaluated based on the JFET width, pillar thickness, and charge imbalance between the p and n pillars. In this study, the device was also modelled for 6.5 kV and 10 kV SiC blocking voltage capabilities; the findings are also discussed. / Denna uppsats fokuserar på att utveckla och karakterisera 3.3 kV kiselkarbidbaserade DMOSFET-transistorer med betydligt lägre framspänningsfall jämfört med kommersiella halvledarkomponenter. Framspänningsfallet och spärrspänningen modifieras genom att använda en pelarliknande halvledarstruktur i drift regionen, dvs. en super-junction [SJ] struktur. På grund av pelarstrukturen under p-bas området, uppträder utarmningsområdet av laddningsbärare både vertikalt och horisontellt och ger ett konstant elektriskt fält genom drift-regionen. Super-junction transistorer har flera fördelar jämfört med komponenter i DMOSFET struktur. På grund av sin kapacitet att motstå högre spärrspänningar och genom att strukturen inte behöver en större enhetscellbredd för att nå högre spärrspänning, så är just nu super-junction strukturer i stort forskningsfokus jämfört med IGBT och DMOSFET komponenter. Kiselkarbid, ett material med ett brett bandgap, möjliggör komponenter för höga temperaturer, höga spärrspänningar, höga elektriska strömmar, samt höga växlingsfrekvenser, har använts för att bygga de undersökta komponenterna. För att generera ett konstant elektriskt fält över drift-regionen, så har dopningsnivåerna för n- och p- pelarna valts för att hålla en bra laddningsbalans mellan dem. Simuleringsresultaten av dessa komponentstrukturer, DMOSFET, halv-SJ MOSFET, och hel-SJ MOSFET är jämförda i detta projekt. Halv-SJ MOSFET transistorn resulterade i ett framspänningsfall på 18.4 mΩcm2 och når en spärrspänning av 4.1 kV. Hel-SJ MOSFET strukturen uppnår ett framspänningsfall på 12.4 mΩcm2 och med spärrspänning av 4.2 kV. En optimerad halv-SJ struktur valdes ut för att genomföra ytterligare TCAD simuleringsstudier om effekterna av JFET bredd, pelartjocklek, samt laddningsobalans mellan n- och p- pelarna. I den här studien simulerades även komponentstrukturer för 6.5 kV och 10 kV spärrspänningsklasser; även dessa resultat diskuteras i rapporten.

Ces travaux s’intègrent dans le projet de recherche SUPERSWITCH dans lequel des solutions alternatives à l’IGBT, utilisées dans les convertisseurs de puissance dans la gamme des tenues en tension 600-1200 V, sont envisagées. Les nouvelles structures du transistor MOS basées sur le principe de Super-Jonction tel que le transistor DT-SJMOSFET et sa terminaison originale, la « Deep Trench Termination » se propose comme alternative aux IGBT. Dans ce contexte, cette thèse se focalise sur la caractérisation de la robustesse de la terminaison DT2 adapté à une diode plane. Après avoir effectué un état de l’art sur les composants de puissances à semi-conducteur unidirectionnels en tension, les terminaisons des composants de puissance et la fiabilité des modules de puissance, un véhicule de test a été conçu en vue de réaliser les différents essais de vieillissement accéléré et suivi électrique. La fiabilité de la terminaison DT2 a été évaluée par des essais expérimentaux et des simulations numériques, dont une méthodologie innovante a été proposée. Au final de nouvelles structures ont été proposées pour limiter les problèmes de délaminage et de charges aux interfaces mis en avant dans notre étude. / This work is a part of the research project SUPERSWITCH in which alternatives solutions to the IGBT, are investigated. This solution was used IGBT in power converters in the 600-1200 V breakdown voltage range. The new MOSFET structures based on the super-junction, such as the DT-SJMOSFET and its "Deep Trench Termination", is proposed as an alternative to IGBT. In this context, this thesis focuses on the robustness characterization of the DT2 termination adapted to a planar diode. After a state of the art on unidirectional voltage power components, the power components termination, and power modules reliability, a test vehicle has been designed in order to carry out different accelerated ageing tests and electrical monitoring. The reliability of DT2 termination was evaluated by experimental tests and numerical simulations. An innovative modeling methodology has been proposed. Finally, new structures have been proposed to limit the delamination failure mechanisms and interface charges problems highlighted in this thesis.

This Diploma thesis is focused on physical and chemical effects which contribute to the decomposition of organic dyes by diaphragm discharge generated in water solutions. Due to the application of DC high voltage source in continuous regime, there is an effect of electrolysis contributing to the dye decomposition by diaphragm discharge. The aim of this work was to find out when the electrolysis is running (or when is the moment of discharge breakdown) and which factors influence the breakdown. The other goal was decomposition of selected textile and food organic dyes by electrolysis itself. In the theoretical part, theory about creation of electrical discharges in aqueous solutions is noted and various types of underwater discharges are described. Background researches about underwater electrical discharges used in the world are mentioned as well as the use of diaphragm discharges and various ways how to remove organic dyes from wastewater. Finally, theories of electrolysis, UV-VIS spectroscopy and basis of other analytical methods useful for detection of organic molecules are described. Experimental part is oriented to experiment procedure which was carried out in a reactor with separated electrode areas. Separation was made by dielectric diaphragm with a pinhole in the centre. Its initial diameter was 0.4 mm. Used chemicals and course of experiments are described in this part, too. First, the breakdown moment in the reactor was investigated (i. e. determination, when only electrolysis was operating) by formation of hydrogen peroxide and measurement of dynamic (time resolved) electrical characteristics. Next, decomposition of selected dyes by electrolysis was carried out. As the decomposition was related to decolorization of the solution, UV-VIS spectroscopy in the range of 350–700 nm was used for determination of dye concentration. Next part focused on results presents various factors which had an effect on breakdown of diaphragm discharge. These factors are kind of used electrolyte, initial conductivity of solution, kind of dye, temperature of solution and type of reactor (or solution volume). From the result, the most important factor is initial solution conductivity. After the determination of the breakdown moment, the electrolysis of organic dyes was performed. The applied current was 10 mA, initial conductivity was 500 µS/cm and used electrolyte was NaCl. Moreover comparison of dye decomposition in dependence on the different applied power was realized. From this comparison one can assume, there is no significant contribution of electrolysis (the efficiency is approximately 15 %) to the diaphragm discharge in aqueous solution.