Surface Plasmons Enhanced Light Emission From ZnO-based Films And Mulitple Quantum Wells

With wide direct band-gap and large exciton binding energy, ZnO is expected to be a promising novel light-emitting material. In order to promote the application of ZnO-based optoelectronc devices, it’s essential to realize the band-gap engineering of ZnO, and improvement of luminescnce properties of ZnO-based materials. Recently, surface plasmons (SPs) arising from a collective of electrons in metals have been widely utilized to realize luminescence enhancement of semiconductors and devices. ZnO, ZnCdO films and ZnO/ZnMgO multiple quantum wells (MQWs) were studied in this thesis. We focused our attention on enhancing the photo-luminescence of those materials by SPs, and analyzed the enhancement mechanism. The primary work is described as follows:(1) ZnO and ZnCdO films were prepared on silicon substrates by pulsed laser deposition (PLD) method. PL results showed that the samples were of good optical quality. The light emission peak was effectively engineered by alloying CdO with ZnO.(2) Metal films were deposited by electron beam evaporation (EBV), and metal nanoparticles were fabricated by the reverse micellar method. Meanwhile, metal micro-patterns and nano-patterns were fabricated by standard photolithography and polystyrene (PS) nanosphere template, respectively.(3) Al nanoparticles prepared by the reverse micellar method were utilized to improve the light emission properties of ZnO and ZnO/ZnMgO MQWs, with PL enhancement ration of7and1.5at room temperature, respectively. The influence of the metal thickness had been studied, and the mechanism lying under the PL enhancement was investigated by SEM, XPS and temperature-dependent PL measurements.(4) A ZnCdO/Metal/Substrate structure was utilized to enhance the photo luminescence of ZnCdO films. PL enhancement ration of7.1and21.2was achieved with Ag film and micro-pattern, respectively. Such improved structure can avoid the reflection loss of the incident and emission light, and protect the ZnCdO films against admage by various chemical classes during the patterning process.