Engineering of III-nitride semiconductors on low temperature Co-fired ceramics

This work presents results in the field of advanced substrate solutions in order to achieve high crystalline quality group-III nitrides based heterostructures for high frequency and power devices or for sensor applications. With that objective, Low Temperature Co-fired Ceramics has been used, as a non-crystalline substrate. Structures like these have never been developed before, and for economic reasons will represent a groundbreaking material in these fields of Electronic. In this sense, the report presents the characterization through various techniques of three series of specimens where GaN was deposited on this ceramic composite, using different buffer layers, and a singular metal-organic chemical vapor deposition related technique for low temperature deposition. Other single crystalline ceramic-based templates were also utilized as substrate materials, for comparison purposes

Material alternative to ITO for transparent conductive electrode in flexible display and photovoltaic devices

The mechanical stability of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) films spin coated onto a UV treated PET substrate was investigated. It was found that the UV exposure modifies the PET surface and improves the wetting conditions for PEDOT:PSS films deposition. The adhesion strength of PEDOT:PSS to UV treated PET surface was found to be 50 N/cm2 versus 19 N/cm2 to the untreated one. Furthermore, the resistance change of PEDOT:PSS on UV treated PET at 20,000 cycles of bending was measured to be only 3.8%. In contrast, the same polymeric films on untreated PET exhibit 8.7% resistance change and the conventional indium tin oxide (ITO) electrode 23.5%, which demonstrates the superior flexibility of the UV PET/PEDOT:PSS electrodes. The transparency of the produced coatings is 81%. Single layer organic light-emitting device with MEH-PPV electroluminescent polymer was successfully fabricated on UV PET/PEDOT:PSS. The electrical measurements indicate the possibility of using UV PET/PEDOT:PSS as a transparent electrode system, replacing ITO in the flexible optoelectronic devices