Development of Al-free ohmic contact to n-GaN

Dae Woo Kim, Jun Cheol Bae, Woo Jin Kim, Hong Koo Baik, Cha Yeon Kim, Wook Kim, Yoon Ho Choi, Chin Kyo Kim, Tae Kyung Yoo, Chang Hee Hong, Sung Man Lee

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1 Citation (Scopus)


We have investigated the electrical properties and interfacial reactions of the Si/Ti-based ohmic contacts to Si-doped n-GaN grown by metal organic chemical vapor deposition and the electrical properties were related to the material reactions. Si/Ti contact system was selected because Ti silicides have a low work function comparable to Al and also Si was used widely as an n-type dopant. As the annealing temperature increased, the specific contact resistance of Si/Ti-based ohmic contacts decreased and showed minimum contact resistance as low as 3.86 × 10-6 Ωcm2 after annealing at 900°C for 3 min under N2 ambient. Our experimental results show that the ohmic behavior of Si/Ti-based contacts were attributed to the low barrier height of Ti-silicide/GaN interface, which was formed through the interfacial reaction between Si and Ti layers. In order to clarify the current conduction mechanism of Si/Ti-based contact, temperature dependent contact resistance measurement was carried out for Au(1000 Å)/Ti(400 Å)/Si(1500 Å)/Ti(150 Å) contact system after annealing at 700°C for 3 min. The contact resistance of Si/Ti-based ohmic contact decreased exponentially with the measuring temperature and so it can be concluded that current flows over the low barrier height by thermionic emission.

Original languageEnglish
Article number71
Pages (from-to)855-860
Number of pages6
JournalJournal of Electronic Materials
Issue number7
Publication statusPublished - 2001

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering
  • Materials Chemistry


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