The objectives of this research are to synthesize and characterize thin films of high resistivity undoped, and semi-conducting p- and n-doped polycrystalline diamond and AlN thin films suitable for the fabrication of high temperature electronic devices, and to investigate the fabrication of high temperature microelectronic devices where silicon devices are not useful.
The approach consists of synthesis of diamond films by microwave plasma enhanced chemical vapor deposition and measurement of their electrical and mechanical properties. The influence of process parameters on the composition, crystal quality, mechanical strength, and the electrical properties of the films will be studied. Advanced materials characterization techniques will be used to characterize nanoscale microstructure, which will be related to the properties of the films. Electrical properties such as I-V and C-V behaviors and carrier concentration will be measured over a range of temperatures. Young?s moduli will be measured on existing Michelson interferometer system. Fabrication of devices such as Schottky diodes, pressure sensor, and a voltage multiplier stack will be investigated.
On a broader scale, the proposed research has potentials for enormous payoffs by developing electronics for operation above 500oC for aircraft, spacecraft, automobiles and nuclear reactors thereby reducing engine maintenance costs, and improving reliability and performance efficiencies. An essential and important component of this research will be to provide education and training of graduate students, post-docs, and undergraduate seniors. In addition, minority/women and high school students will be mentored and exposed to this research through programs at our university. A significant outreach to high schools is proposed.
Present day semiconductor technology is based on devices made from silicon material. However, this material performs poorly at high temperatures and breaks down when the electric field across it is very high. Therefore, silicon is unsuitable for device applications where high temperatures and high voltages are involved. Diamond and AlN are wide bandgap semiconductor materials. The large bandgap of these materials makes them tolerate high temperatures, high electric fields, and also high radiation environments. Therefore, the materials and device concepts we have developed can be applied to not only for high temperature and high power electronics, but are also applicable for devices used in high radiation environments such as the core of a nuclear reactor or for use in outer space. Further, the optical emission wavelengths for these two materials are in the ultraviolet regime. Therefore, our research opens up the opportunity to build diamond-on-AlN heterostructure devices for optoelectronics applications. Also, high temperature and high power electronics are used in aerospace, automobile, energy, and defense applications. The development of such technology will lead to improved efficiency, cost savings, and improved reliability in almost every segment of day-to-day life including reduced power consumption, improved automobile and aircraft fuel efficiency, and reduced greenhouse gas emissions and pollution. Our research also placed a significant emphasis on undergraduate and graduate student training. The skills that the students learn in our laboratory include materials synthesis, materials processing, device fabrication and testing. These skills are highly transferable and are valuable to the high-tech industry. The graduates from our research groups have been placed in premier high-technology companies such as Intel. Therefore, our research has directly contributed to the development of human resources essential to maintain the economic and technological leadership of the United States of America.
