Boron-oxygen complex yields n-type surface layer in semiconducting diamond

Xiaobing Liu; Xin Chen; David J Singh; Richard A Stern; Jinsong Wu; Sylvain Petitgirard; Craig R Bina; Steven D Jacobsen

doi:10.1073/pnas.1821612116

Boron-oxygen complex yields n-type surface layer in semiconducting diamond

Proc Natl Acad Sci U S A. 2019 Apr 16;116(16):7703-7711. doi: 10.1073/pnas.1821612116. Epub 2019 Apr 1.

Authors

Xiaobing Liu^{1

2}, Xin Chen^{1

2}, David J Singh³, Richard A Stern⁴, Jinsong Wu⁵, Sylvain Petitgirard⁶, Craig R Bina², Steven D Jacobsen⁷

Affiliations

¹ School of Physics and Physical Engineering, Qufu Normal University, Qufu, 273165 Shandong, China; xiaobing.phy@qfnu.edu.cn chenxin@qfnu.edu.cn s-jacobsen@northwestern.edu.
² Department of Earth and Planetary Sciences, Northwestern University, Evanston, IL 60208.
³ Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211.
⁴ Canadian Centre for Isotopic Microanalysis, Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, AB T6G 2E3, Canada.
⁵ Northwestern University Atomic and Nanoscale Characterization Experimental, Northwestern University, Evanston, IL 60208.
⁶ Bayerisches Geoinstitut, University of Bayreuth, 95444 Bayreuth, Germany.
⁷ Department of Earth and Planetary Sciences, Northwestern University, Evanston, IL 60208; xiaobing.phy@qfnu.edu.cn chenxin@qfnu.edu.cn s-jacobsen@northwestern.edu.

Abstract

Diamond is a wide-bandgap semiconductor possessing exceptional physical and chemical properties with the potential to miniaturize high-power electronics. Whereas boron-doped diamond (BDD) is a well-known p-type semiconductor, fabrication of practical diamond-based electronic devices awaits development of an effective n-type dopant with satisfactory electrical properties. Here we report the synthesis of n-type diamond, containing boron (B) and oxygen (O) complex defects. We obtain high carrier concentration (∼0.778 × 10²¹ cm^-3) several orders of magnitude greater than previously obtained with sulfur or phosphorous, accompanied by high electrical conductivity. In high-pressure high-temperature (HPHT) boron-doped diamond single crystal we formed a boron-rich layer ∼1-1.5 μm thick in the {111} surface containing up to 1.4 atomic % B. We show that under certain HPHT conditions the boron dopants combine with oxygen defects to form B-O complexes that can be tuned by controlling the experimental parameters for diamond crystallization, thus giving rise to n-type conduction. First-principles calculations indicate that B₃O and B₄O complexes with low formation energies exhibit shallow donor levels, elucidating the mechanism of the n-type semiconducting behavior.

Keywords: boron; defects; diamond; high pressure; semiconductor.