Length versus radius relationship for ZnO nanowires grown via vapour phase transport

We model the growth of ZnO nanowires via vapour phase transport and examine the relationship predicted between the nanowire length and radius. The model predicts that the lengths of the nanowires increase with decreasing nanowire radii. This prediction is in very good agreement with experimental data from a variety of nanowire samples, including samples showing a broad range of nanowire radii and samples grown using a lithographic technique to constrain the nanowire radius. The close agreement of the model and the experimental data strongly support supporting the inclusion of a surface diffusion term in the model for the incorporation of species into a growing nanowire

Effect of the polymer emission on the electroluminescence characteristics of n-ZnO nanorods/p-polymer hybrid light emitting diode Effect of the Polymer Emission on the Electroluminescence Characteristics of n-ZnO Nanorods/p-Polymer Hybrid Light Emitting D

Abstract Hybrid light emitting diodes (LEDs) based on zinc oxide (ZnO) nanorods and polymers (single and blended) are fabricated and characterized. The ZnO nanorods were grown by the chemical bath deposition method at 50 o C. Three different LEDs, either with blue emitting, orange-red emitting or their blended polymer together with ZnO nanorods were fabricated and studied. The current-voltage characteristics show good diode behavior with ideality factor in the range of 2.1 to 2.27 for all the three devices. The electroluminescence spectrum (EL) of the blended device has an emission range from 450nm to 750nm, due to the intermixing of the blue emission generated by the poly(9,9-dioctylfluorene) denoted as PFO with orange red emission produced by the poly(2-methoxy-5(20-ethyl-hexyloxy)-1,4-phenylenevinylene) 1,4-phenylenevinylene) symbolize as MEH PPV combined with the deep band emission (DBE) of the ZnO nanorods i.e. it covers the whole visible region and manifested as white light. The CIE colour coordinates showed bluish, orange-red and white emission from the PFO, MEH PPV and blended LEDs with ZnO nanorods, respectively. These results indicate that the choice of the polymer with proper concentration is critical to the emitted colour in ZnO nanorods/p-organic polymers LEDs and careful design should considered to obtain intrinsic white light sources

Effect of the polymer emission on the electroluminescence characteristics of n-ZnO nanorods/p-polymer hybrid light emitting diode

Hybrid light emitting diodes (LEDs) based on zinc oxide (ZnO) nanorods and polymers (single and blended) were fabricated and characterized. The ZnO nanorods were grown by the chemical bath deposition method at 50A degrees C. Three different LEDs, with blue emitting, orange-red emitting or their blended polymer together with ZnO nanorods, were fabricated and studied. The current-voltage characteristics show good diode behavior with an ideality factor in the range of 2.1 to 2.27 for all three devices. The electroluminescence spectrum (EL) of the blended device has an emission range from 450 nm to 750 nm, due to the intermixing of the blue emission generated by poly(9,9-dioctylfluorene) denoted as PFO with orange-red emission produced by poly(2-methoxy-5(20-ethyl-hexyloxy)-1,4-phenylenevinylene) 1,4-phenylenevinylene) symbolized as MEH PPV combined with the deep-band emission (DBE) of the ZnO nanorods, i.e. it covers the whole visible region and is manifested as white light. The CIE color coordinates showed bluish, orange-red and white emission from the PFO, MEH PPV and blended LEDs with ZnO nanorods, respectively. These results indicate that the choice of the polymer with proper concentration is critical to the emitted color in ZnO nanorods/p-organic polymer LEDs and careful design should be considered to obtain intrinsic white light sources

Phase Retrieval of Vitreous Floaters in Presence of Aberrations

Maģistra darbs ir uzrakstīts latviešu valodā uz 45 lapaspusēm. Tas satur 34 attēlu, 4 tabulas, un 46 atsauces uz literatūras avotiem. Darba mērķis: Izvērtēt, kā optiskās sistēmas parametri ietekmē stiklveida ķermeņa apduļķojumu fāzes noteikšanu optiskās sistēmas aberāciju klātbūtnē. Metode: Aberāciju/apduļķojumu simulācijas, optisko parametru ietkmes izvērtēšana MATLAB vidē. Rezultāti un analīze: Apduļķojumi ir rekonstruējami aberāciju klātbūtnē. Ja trokšņa un fona amplitūda ir vienāda, fons kvalitāti pazemina vairāk. Bitu dziļuma pazemināšana samazina trokšņa un fona efektu. Datu ieguves biežuma palielināšana uzlabo rekonstrukcijas kvalitāti. Secinājumi: Troksnis, bitu dziļums, fons, datu ieguves biežums ietekmē apduļkojumu fāzes noteikšanu.Master thesis is written in Latvian on 45 pages. It contains 34 images, 4 tables, 46 references to literature sources Purpose: To evaluate how optical systems affects detemination of vitreous floater phase in optical system aberration presence. Methods: Aberration/floater simulation, evaluation of different optical systems in MATLAB. Results and analysis: Vitreous floaters can be retrieved in presence of aberrations. If the amplitude of noise and background is equal, the background compromises the quality of the phase more. Lowering the bit depth reduces the effect of noise and background. Increasing the oversampling ratio improves the quality of the phase. Conclusion: Noise, bit depht, oversampling, background affects determination of floater phase