Elizabeth City State University's Research Initiation Award entitled - Fabrication and Characterization of Composite Contacts on Wide Band Gap Semiconductor for High Temperature Application in Air - is a collaborative effort between the principal investigator at Elizabeth City State University (ECSU) and faculty at the Center for Materials Research at Norfolk State University (CMR-NSU). The project supports materials research activities by faculty at ECSU and CMR-NSU, as well as research education and training of undergraduate students at ECSU. The project has the potential to contribute to the undergraduate education knowledge base through integration of education and research. It also provides summer research experiences to high school students.
The research objective of the proposal is to explore vacuum sputtered nanolayers (< 100 nm thick) of conducting refractory metals, metal silicides and titanium-tungsten, as oxidation and diffusion barrier layers to protect contacts on Wide Band Gap (WBG) semiconductor devices that will function in a high temperature environment. The effectiveness and reliability of the devices operating at high temperature (> 500º C ) over an extended period of time (> 5000 hours) will depend on the interfacial reactions, oxygen defect and mobility or accumulation of carbon close to the contact/barrier layer interface. Rutherford Backscattering Spectrometry (RBS), Auger Electron Spectroscopy (AES) and Electron Microscopy (TEM & SEM) will be employed to physically characterize interface reaction at such elevated annealing temperatures.
The goal of the Research Initiation Awards (RIA) grant is to initiate viable faculty research activities in a minority serving institution. The research activities are expected to involve undergraduate student participation and executed in collaboration with established research center. At ECSU, the goals of the RIA grants include the following: Goal1: Initiate materials research at Elizabeth City University (ECSU) in collaboration with the Center for Materials Research at Norfolk State University (NSU). Goal 2: To develop and evaluate barrier layers (less than 100 nm thick), as part of the sputter-deposited metallization scheme, that can protect important contact metal on electronic devices operating at an elevated temperature environment (> 500°C) for a long time (> 5000 hours). Goal 3: To investigate the optical properties (reflectance and transmittance) and optical switching in the wavelength region from mid-infrared to ultraviolet as a function of temperature in the environment. Goal 4: Engage undergraduate students at ECSU in collaborative material science research and education. Goal 5: Establish High School Summer Research Internship that engage local high school students in materials research activities over the summer. The two materials research projects under this grant and results: Project 1: Focused on the development of contact metallization for Wide Band Gap (WBG)-based devices that will operate at an elevated temperature environment where a traditional silicon device cannot operate. We study the diffusion properties and effectiveness of sputter-deposited barrier layer (< 100 nm thick), as a part of the composite metallization structure for WBG semiconductor devices. Tantalum rich Ta-Si-N barrier layer was developed and its effectiveness evaluated over hundreds of hours on CVD diamond layer. This work was presented during the fall 2012 Materials Research Society Conference at Boston [1]. The metallization is still been evaluated on WBG based Schottky device, some of our results will be presented during the fall 2013 MRS conference. The abstract has been accepted. Project 2: Focused on depositing transition metal oxides on quartz substrates by reactive magnetron sputtering of transition metal targets in argon, oxygen and nitrogen gas mixtures. The goal of this project is to investigate the optical properties (reflectance and transmittance) and optical switching in the wavelength region from mid-infrared to ultraviolet as a function of temperature in the environment. Vanadium dioxide film that shows thermochromic characteristics have been produce in our research lab. Our research effort to reactively sputter vanadium dioxide films from vanadium target is yet to be successful. We reported some of the work on this project during the fall 2012 MRS conference in Boston [2]. Our abstract to present our recent success in this project was accepted for fall 2013 MRS conference. Important Outcomes and Achievements: Some of the results of this research have enabled the investigators to secure another NSF MRI funding to purchase SEM/EDS for further research/education activities. This instrument will broaden the materials research base at ECSU and encourage interdisciplinary and collaborative research within the university. As a result of the program advertisement at neighboring high schools and at ECSU, the physics program has 5 undergraduates (physics majors) in the university physics 1 course (PHYS 191) this fall 2013. The highest we have had in any one class since the PI joined the faculty at ECSU in 2007. Two articles were published based directly on the results from these projects in 2013. Two abstracts were submitted and accepted for the 2013 Fall Materials Research Society Conference. Seven (7) undergraduate students worked with the PI on these projects during the period of the grant. Majority of the students worked with the PI in the summer as well during the academic year. A total of twelve (12) high school students from neighboring schools worked with the PI and undergraduate students in the summer of 2012 and 2013. The students’ stipend was provided by this grant. The PI took two undergraduate students to fall 2012 MRS conference at Boston. It was their first exposure to international scientific conference and in fact it was their first time flying in airplane. The student presented their poster during the conference. It was a great experience for them and for the PI as well. The travel expenses were covered by the grant. (1) A.V. Adedeji, M.R. Ross, N. Hamden, A.K. Pradhan, T. Isaacs-smith and A.C. Ahyi, Effective refractory metal alloy barrier layer for high temperature microelectronic device applications,MRS Online Proceedings Library / Volume 1519 / 2013 (2) A.V. Adedeji, S.D. Worsley, T.L. Baker, R. Mundle, A.K. Pradhan, A.C. Ahyi and T. Isaacs-Smith, Dynamic properties of spectrally selective reactively sputtered transition metal oxides,MRS Online Proceedings Library / Volume 1494 / 2013
