Ohmic Contacts to Bulk N-type Gallium Nitride

"Kyma Technologies and NCSU will collaborate to produce ohmic contacts to single crystal gallium nitride (GaN) substrates. We propose to develop metallization schemes for ohmic contacts to GaN substrates for device fabrication. This will be of the utmostimportance for producing devices with a vertical device structure on a native gallium nitride substrate. Gallium nitride devices produced on sapphire have a horizontal structure which increases die size and limits productivity. The objective of Phase Iis to identify viable Ohmic contacts to bulk n-type GaN substrates, and to investigate the polarity-dependence in Ohmic contact characteristics. To achieve this goal, transition metal based Ohmic contacts will be prepared on GaN, and itspolarity-dependency will be explored. These are of great importance since low specific resistivity Ohmic contact will enhance overall device performance. It is also of importance to investigate polarity dependence on Ohmic contact characteristics sincepolarity will significantly influence electrical characteristics of metal-semiconductor contact. Metallization of GaN wafers will be useful in developing various types of microelectronic and optoelectronic devices. The development of ohmic contacts forGaN wafers will result in vertical device structures, and subsequently will increase number of die per wafer. The advent of advanced materials processing technology has ushered in the era of GaN based optoelectronics. In spite of this development, a lackof the availability of native substrates has hindered further progress in GaN based device technology. However, through substantial research and development, bulk GaN substrates are now becoming a reality. Low defect density gallium nitride films willbenefit many microelectronic and optoelectronic devices. This material will lead to the commercialization of blue lasers in data storage and solid-state white lighting. The development of contacts to GaN substrates is fundamental in commercialization ofthese devices. The development of vertical device str