ZnO and Mg x Zn 1-x O are technologically promising materials for luminescence applications in the ultraviolet (UV) range. ZnO has a bandgap ~3.3 eV, while MgO has a bandgap ~7.5 eV. The alloy system of Mg x Zn 1-x O may provide an optically tunable family of materials capable of efficient luminescence in the range of 3.3 to 7.5 eV, depending on the alloy composition x. To date Mg x Zn 1-x O thin films [1-2] as well as free-standing nanocrystals have been achieved [3]. One of our recent research efforts focuses on the creation of Mg x Zn 1-x O compacted nano- crystalline alloy samples (CNAS) and on studies concerning their optical and material properties. The objective is to achieve a new form of Mg x Zn 1-x O material of luminescence energy by design. Mg x Zn 1-x O CNAS were created via hard-pressing of MgO and ZnO nanocrystals followed by annealing. We based our process on existing technologies: namely we used MgO and ZnO nanocrystals as the parent materials that are readily available in industry and are cost-effective. Figure 1 presents a photograph and an scanning electron microscope (SEM) image of the CNAS. The CNAS’s exhibit room-temperature photoluminescence (PL), as seen in Fig. 2. Moreover, an energy blueshift up to ~1.12 eV was achieved, which is comparable to that observed previously for high quality thin films. This is a significant shift; to put it in perspective, the human eye is sensitive to a range of ~1.5 eV. The CNAS have potential applications in photonic, display, and lighting technologies. 1. A. Ohtomo et al. Appl. Phys. Lett. 72, 2466 (1998). 2. A.K. Sharma, J. Narayan, et al. Appl. Phys. Lett. 75, 3327 (1999). 3. Bergman et al. Appl. Phys. Lett. 88, (2006). Figure 1. Three CNAS placed on a 2” Si wafer. The inset is the SEM image of the CNAS. Figure 2. The PL spectra of CNAS’s. The pure ZnO CNAS has PL energy at 3.31 eV, the Mg 0.1 Zn 0.9 O at 3.57, and the Mg 0.4 Zn 0.6 O at 4.43 eV. Novel Bandgap Engineered Luminescent Materials Leah Bergman DMR

Education and Outreach: The graduate students who are currently involved and supported via this grant are John L. Morrison and Heather Hoeck. Additionally Erin Casey, an undergraduate student, is supported via this grant. John Morrison graduated with a Masters degree in Physics in December 2006, and chose to pursue his Ph.D. degree under the continued supervision of the PI. Erin Casey plans in Spring 2008 to apply to graduate school at the University of Idaho to peruse her Ph.D. in Physics under the supervision of the PI. The PI strongly encourages undergraduate students to continue their higher education in physics. She is currently conducting an undergraduate seminar at the Department of Physics, University of Idaho, the objective of which is to orient students towards research and graduate school in sciences. The PI participates each summer in the NSF- REU program. In the summer of 2007 she hosted two undergraduate students: Erin Casey from the University of Idaho and Adam J. Sypniewski from Alma College, Michigan. The two REU students participated in research concerning the topic of compacted nanocrystalline alloy samples. Novel Bandgap Engineered Luminescent Materials Leah Bergman DMR CAREER Figure 1. The PI presenting a talk on the topic of luminescent materials at the undergraduate seminar.