<> "The repository administrator has not yet configured an RDF license."^^ . <> . . "Surface Functionalization of Nickel Oxide and Gallium Nitride for Hybrid Opto-Electronics"^^ . "This thesis examines the influence of surface functionalization\r\nby self-assembled monolayers (SAMs) on two different materials, (i) nickel\r\noxide and (ii) gallium nitride.\r\n(i) Thin solution-processed films of nickel oxide (sNiO) were modified with\r\ndipolar self-assembled monolayers of 4-cyanophenyl-phosphonic acid (CYNOPPA)\r\nto improve the energy level alignment and the chemical compatibility to the donor\r\nin F4ZnPc:C60 organic photovoltaic devices. A detailed analysis of infrared and\r\nphotoelectron spectroscopy showed the chemisorption of the molecules with a\r\nnominal layer thickness of around one monolayer. The spectroscopic results gave\r\nfurther insight into the chemical composition of the SAM. Density functional theory\r\ncalculations were employed to reveal energetically allowed binding configurations of\r\nthe phosphonate anchor group. CYNOPPA successfully increased the work function\r\nof the sNiO up to 5.1-5.2 eV, leading to a well-matched Fermi level of the hole-contact\r\nlayer to the ionization potential of the donor. Unexpectedly, the improved alignment\r\ndid not lead to a higher power conversion efficiency. Instead, a significant reduction\r\nof the fill factor was observed, which was assigned to the formation of a transport\r\nbarrier due to a low conductive interface region. However, it was shown that the\r\nbarrier can be reduced by doping the oxide hole-contact layer and thereby increase\r\nits charge carrier density.\r\n(ii) For the goal of GaN nanowire surface state passivation and control of the corresponding\r\nband bending, different GaN planes were functionalized with self-assembled\r\nmonolayers. A step-by-step procedure of solvent cleaning, plasma treatment and\r\nHCl etching was developed to guarantee clean surfaces for SAM growth. X-ray\r\nphotoelectron spectroscopy (XPS) measurements showed that oxygen as well as\r\ncarbon contents could be reduced to a minimum with this procedure. SAM precursor\r\nwith different anchoring groups were tested to find the best binding partner for\r\nthe GaN surface. The SAM quality and passivation functionality was determined\r\nby Kelvin probe surface photovoltage and contact angle measurements. It was\r\nshown that amines and thiols suffer from low surface coverage on GaN(0001) under\r\nambient conditions. Hence, an oxide template layer was grown for the attachment\r\nof phosphonic acids (PAs). Two phosphonic acids with different intrinsic dipole\r\nmoments were applied to oxidized high quality GaN(0001) and GaN(1100) surfaces\r\ngrown by molecular beam epitaxy. XPS and contact angle measurements revealed\r\ndense monolayer coverage of the PA-SAMs. Despite the oxide buffer layer, the band\r\nbending of the GaN was reduced by the chemisorption and molecular backbones of\r\nthe PAs. Continuous-wavelength photoluminescence (cw-PL) measurements showed\r\nan increase of the total PL intensity, which suggests that a reduction of the band\r\nbending is essential for high luminescence quantum yields."^^ . "2017" . . . . . . . "Sebastian"^^ . "Hietzschold"^^ . "Sebastian Hietzschold"^^ . . . . . . "Surface Functionalization of Nickel Oxide and Gallium Nitride for Hybrid Opto-Electronics (PDF)"^^ . . . "2017_Dissertation_SebastianHietzschold.pdf"^^ . . . "Surface Functionalization of Nickel Oxide and Gallium Nitride for Hybrid Opto-Electronics (Other)"^^ . . . . . . "indexcodes.txt"^^ . . "HTML Summary of #23869 \n\nSurface Functionalization of Nickel Oxide and Gallium Nitride for Hybrid Opto-Electronics\n\n" . "text/html" . . . "530 Physik"@de . "530 Physics"@en . .