Heteroeklem güneş hücreleri için saçtırma yöntemi ile büyütülmüş molibdan oksit ve magnezyum katkılı çinko oksit yük taşıyıcı tabakaların karakterizasyonu.

Group IV semiconductors can easily be doped by group III and V elements to possess p and n type behavior, respectively, which enables homojunction solar cell designs. However, most of the compound semiconductors including CIGS, CdTe and perovskite can intrinsically be either n or p type. Therefore, heterojunction structures with well-aligned conduction bands between the absorber and electron transport layer (ETL) and well-aligned valence bands between the absorber and hole transport layer (HTL) are required. This thesis aims to investigate structural, optical and electrical properties of molybdenum oxide (MoOx) HTL and magnesium-doped zinc oxide (ZnxMg1-xO) ETL fabricated by reactive rf magnetron co-sputtering for heterojunction solar cells. MoO3 is a semiconductor with a band gap of 3.3 eV; however, defect states in oxygen-deficient MoOx make it act like a high work function metal. In this study, oxygen vacancies were created both by stoichiometry control during deposition and by post annealing. Defect states formation near the valance band edge and its influence on work function of the material were analyzed by X-ray photoelectron spectroscopy (XPS). Crystallographic properties of MoOx films were examined by X-ray diffraction (XRD). Refractive indices, extinctionvi coefficients and thicknesses of thin films were determined by spectroscopic ellispsometry. Finally, transmittance and reflectance spectra of MoOx thin films were measured. ZnOx is an alternative ETL to replace conventional ones due to its relatively low cost and high electrical conductivity. In this study, band gap of ZnxMg1-xO was altered by Mg doping. Optical band gap studies were conducted by Tauc plot analysis using transmission spectra. Crystal structures of the samples were measured by XRD to illustrate adverse effect of Mg doping and healing effect of introducing oxygen during deposition. Spectroscopic ellipsometry characterization was performed to determine optical constants of thin films. Finally, perovskite solar cells were fabricated using sputtered ZnOx.M.S. - Master of Scienc

Yüksek Verimli PERC Güneş Pilleri için Pikosaniye Atımlı Lazer ile Lazer Doping Yoluyla Seçici Emitör Oluşumu

In this study, we develop a POCl3 diffusion recipe so that we obtain a thicker phosphosilicate glass layer for laser doping. The formation of a laser doped selective emitter is achieved by utilizing an industrial-type picosecond pulsed laser operating at 532 nm (green) wavelength () and pulse repetition rate (frep) of 1 MHz. To demonstrate the selective emitter concept, sheet resistance reduction of the laser processed region after tube furnace diffusion is provided. In addition, produced samples are metalized and the difference of contact resistivities of both homogenous emitter and laser doped emitter is shown. By applying a moderate amount of heat accumulation on the surface, specific contact resistivity of the laser doped region is reduced to around 3 mΩ.cm2. We report process details and results in this paper

Electrical, optical and surface characterization of reactive RF magnetron sputtered molybdenum oxide films for solar cell applications

Thin films of molybdenum oxide (MoOx) were fabricated by radio frequency (RF) reactive magnetron sputtering technique with various oxygen flow rates and the deposition pressure fixed at 4 mTorr. The stoichiometry, composition, chemical binding energy, electrical, and optical properties of the sputtered MoOx films were examined. The deposited films were characterised by x-ray photoelectron spectroscopy (XPS), capacitance-voltage measurement (CV), spectroscopic ellipsometer (SE), and ultraviolet-visible spectroscopy (UV-VIS). XPS studies of the film indicated the presence of Mo5+ and Mo6+ oxidation states within the film. The deposited sputtered films were semiconducting in nature with the highest work function of 5.92 eV observed for MoOx. The stoichiometry for RF sputtered MoOx (x < 3) was found to be 2.73. CV analysis indicated that density of defect states in the MoOx films decreased with the corresponding increase in the oxygen flow rate. SE studies have shown that the refractive indices of the as-deposited films ranged from -1.8-2.05 at nominal wavelength of 632.8 nm. Similarly, high transmittance and large band gap values of sputtered MoOx were observed. It was proved that deposited MoOx is of n-type character with the Fermi level variation observed within the band gap of MoOx upon changing the oxygen flow rate

Mechanical and optical properties of SiO2 thin films deposited on glass

The optical and mechanical properties of amorphous SiO2 films deposited on soda-lime silicate float glass by reactive RF magnetron sputtering at room temperature were investigated in dependence of the process pressure. The densities of the films are strongly influenced by the process pressure and vary between 2.38 and 1.91 g cm(-3) as the pressure changes from 0.27 to 1.33 Pa. The refractive indices of the films shift between 1.52 and 1.37, while the residual compressive stresses in the deposited films vary in the range from 440 to 1 MPa. Hardness and reduced elastic modulus values follow the same trend and decline with the increase of process pressure from 8.5 to 2.2 GPa and from 73.7 to 30.9 GPa, respectively. The abrasive wear resistance decreases with the density of the films

Fotovoltaik malzemelerin fotolüminesans haritasının çıkarılması

Önerilen birleştirilmiş tez projesinin amacı, yukarıda bilgilerin verilen 10 öğrencinin de tezleri çerçevesinde üretikleri örneklerin fotolüminesans haritalarının çıkarılmasıdır. Proje çerçevesinde, ODTÜ Güneş Enerjisi Araştırma ve Uygulama Merkezinde bulunan fotolüminesans sistemi iyileştirilecek, aşağıda detayları verilen ölçümler yapılacak, sonuçlar incelenecek, uygun olanlar rapor edilecek ve yayınlanacaktır.Proje kapsamında fotolüminesans yöntemi ile çalışılacak sistemler şunlardır.1) Güneş hücreleri için yüksek kaliteye sahip silisyum 2) Güneş hücreleri için özgün sıyırma yöntemi ile elde edilmiş ince silisyum3) Güneş hücreleri için perovskite (CH3NH3PbI3)4) Silisyum üzerine üretilmiş tek kristal germanyum tabakaları5) Optik üst çevirim eldesi için erbiyum silika

Mechanical and optical properties of SiO2 thin films deposited on glass

The optical and mechanical properties of amorphous SiO2 films deposited on soda-lime silicate float glass by reactive RF magnetron sputtering at room temperature were investigated in dependence of the process pressure. The densities of the films are strongly influenced by the process pressure and vary between 2.38 and 1.91 g cm(-3) as the pressure changes from 0.27 to 1.33 Pa. The refractive indices of the films shift between 1.52 and 1.37, while the residual compressive stresses in the deposited films vary in the range from 440 to 1 MPa. Hardness and reduced elastic modulus values follow the same trend and decline with the increase of process pressure from 8.5 to 2.2 GPa and from 73.7 to 30.9 GPa, respectively. The abrasive wear resistance decreases with the density of the films