Characteristics of Ohmic Contacts to n-Type Boron Phosphide

• Published in: Japanese Journal of Applied Physics 2013-03, Vol.52 (3), p.031201-031201-8
• Main Authors: Ino, Yuji, Nishimura, Suzuka, Hirai, Muneyuki, Matsumoto, Satoru, Terashima, Kazutaka
• Format: Article
• Language: English
• Subjects: Aluminum; Annealing; Boron phosphides; Contact resistance; Devices; Gold; Ohmic; Titanium
• ISSN: 0021-4922; 1347-4065
• DOI: 10.7567/JJAP.52.031201

We grew n-type boron phosphide (BP) (100) on a p-type Si(100) substrate by hydride vapor phase epitaxy. Electrical contacts are important for electrical evaluations and device applications, but the resistivity of ohmic contacts to BP has been little studied. We evaluated the contact characteristics for Al, Au, In, Ti, and Pt by annealing at temperatures in the range 300--500 °C for annealing times up to 50 min using a circular transmission line model pattern. Ohmic characteristics were obtained for the Al, Au, In, and Ti contacts. For the ohmic samples, we calculated the specific contact resistance $\rho_{\text{c}}$ and observed a metal--BP interface by cross-sectional transmission electron microscopy. The minimum specific contact resistance $\rho_{\text{c}}$ was $2\times 10^{-5}$ $\Omega$ cm 2 for the Au/In/n-BP sample annealed at 500 °C for 50 min. For the present samples, thermionic-field emission is considered to be the dominant carrier transport process across the metal--BP interface.