A Comparative Optimization of Electrical Properties and Surface Morphology of Ti/Al/Ta/Au Ohmic Contacts in AlGaN/GaN HEMTs on Si(111), Sapphire, 4H-SiC Substrates

Abstract:

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In the process of characterizing AlGaN/GaN HEMTs on Si (111), Sapphire, 4H-SiC substrates, various Rapid Thermal Annealing (RTA) conditions for the Ti/Al/Ta/Au ohmic contact process and the resulting surface analysis have been investigated. In order to achieve a low ohmic contact resistance (RC) and a high quality surface morphology, we tested seven steps (800 °C to 920 °C) annealing temperatures and two steps (15, 30 sec) annealing times. According to these annealing temperatures and times, the optimal ohmic resistance of 3.62 × 10-6 Ohm • cm2 on Si(111) substrate, 9.44 × 10-6 Ohm • cm2 on Sapphire substrate and 1.24 × 10-6 Ohm • cm2 on 4H-SiC substrate are obtained at an annealing temperature of 850 °C and an annealing time of 30 sec, 800 °C and an annealing time of 30 sec and 900 °C and an annealing time of 30 sec, respectively. The surface morphologies of the ohmic contact metallization at different annealing temperatures are measured using an Atomic Force Microscope (AFM). AFM morphology Root Mean Square (RMS) level determines the relationship of the annealing temperature and the annealing time for all of the samples. According to these annealing temperatures and times, the optimal ohmic surface RMS roughness of 13.4 nm on Si(111) substrate, 3.8 nm on Sapphire substrate and 2.9 nm on 4H-SiC substrate are obtained at an annealing temperature of 850 °C and an annealing time of 30 sec, 800 °C and an annealing time of 30 sec and 900 °C and an annealing time of 30 sec, respectively.

Info:

Periodical:

Advanced Materials Research (Volumes 538-541)

Edited by:

Liancheng Zhao, Haowei Wang and Changfa Xiao

Pages:

2207-2210

DOI:

10.4028/www.scientific.net/AMR.538-541.2207

Citation:

S. J. Cho et al., "A Comparative Optimization of Electrical Properties and Surface Morphology of Ti/Al/Ta/Au Ohmic Contacts in AlGaN/GaN HEMTs on Si(111), Sapphire, 4H-SiC Substrates", Advanced Materials Research, Vols. 538-541, pp. 2207-2210, 2012

Online since:

June 2012

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$35.00

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