537 / 2019-03-20 10:24:05

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

Diamond, boron, defects, semiconductor, high pressure

全体主题 > High Pressure Physics and Materials Science

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 ×
10^21 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 B3Oand B4O complexes with low formation
energies exhibit shallow donor levels, elucidating the mechanism of
the n-type semiconducting behavior.