III-V semiconductors have higher charge carrier mobilities than silicon and are used in photovoltaic devices, optical sensors, and emitters. The high injection velocities obtained with III-V channels allow for faster transistors with low power consumption. However, the large-scale implementation in electronic devices is currently limited by the defective interface formed between III-Vs and their oxides. Clean III-V surfaces are highly reactive in air and form amorphous oxides that lead to a high density of dangling bonds. Satisfying these dangling bonds has been associated with an improvement in electrical performance, directing the development of strategies that decrease the surface reactivity (chemical passivation) and the density of surface states that cause power dissipation (electrical passivation). Sulfur bonds easily to III-V surfaces and has been used to chemically and electrically passivate GaAs. In this work, we investigated liquid phase sulfur chemistries in the chemical passivation of clean InSb(100) and In0.53Ga0.47As(100) surfaces terminated by their group V elements. Our strategy consisted of maximizing the number of bonds between sulfur and antimony or arsenic. A long alkane chain thiol, 1-eicosanethiol (ET, 20 carbon atoms), was used to produce a hydrophobic surface and deposit a dense organic layer by taking advantage of the van der Waals interactions between thiol molecules. The first part of the study involved the optimization of the thiol deposition process on InSb. Self-assembled alkanethiol monolayers were formed by immersing clean InSb substrates in ET solutions in ethanol for 20 h. The layers prevented the formation of detectable oxides for 20 min based on the O Auger x-ray photoelectron spectroscopy (XPS) peak. The thiol layer was completely removed by heating the surface to 227 C in vacuum. In the second part of the study, a 20 h ET deposition was performed on In0.53Ga0.47As(100), and re-oxidation was prevented for up to 4 min based on the O 1s XPS peak. The alkanethiolate layer was removed by heating the samples to 350 C in vacuum. The sulfur coverage after 20 min and 20 h ET depositions was increased by performing a second immersion in (NH4)2S without modifying the thickness of the layer. The best process studied consisted of a 20 h immersion in ET solution followed by a short (NH4)2S step, preventing the formation of oxides for up to 9 min. This is due to the presence of available surface sites and weakly bonded molecules in the layer after a long 20 h ET process. The chemical passivation effect is not uniquely influenced by surface termination, roughness, or lattice constant, but is rather a result of a combination of these factors. Future work will involve the fabrication and electrical characterization of III-V devices modified with various chemical passivation strategies.

This thesis deals with a lifetime measurement of current carriers in silicon solar cell structures. In the first chapter there is a description of several recombination models and their participation at a final effective lifetime value. By using these recombination models in a computer simulation it is possible to receive approximate evaluation of some important silicon solar cell structure parameters. The PC1D simulation program was used for this thesis. For the lifetime measurement of real test-wafers two methods were used: QSSPC (quasi-steady-state photoconductance) and MW-PCD (microwave photoconductance decay). There is a detail description of these methods, used measurements machines and differences between both of them in the chapter four. The main objective of the thesis is mentioned in the last chapter, which is mainly focused on a chemical passivation of silicon wafers and deals with a problem of post-passivation wafer cleaning. There are three passivation techniques mentioned: the iodine in ethanol solution, the iodine and polymer in ethanol solution and the quinhydron in methanol solution. In two cases a results, that are adequate to return the tested wafers in the manufacture process, were achieved.

This master´s thesis deals with an examination of different solution types a for the chemical passivation of a silicon surface. Various solutions are tested on silicon wafers for their consequent comparison. The main purpose of this work is to find optimal solution, which suits the requirements of a time stability and start-up velocity of passivation, reproducibility of the measurements and a possibility of a perfect cleaning of a passivating solution remainig from a silicon surface, so that the parameters of a measured silicon wafer will not worsen and there will not be any contamination of the other wafers series in the production after a repetitive return of the measured wafer into the production process. The cleaning process itself is also a subject of a development.