Microstructure and field electron emission properties of boron doped diamond films

Abstract

Boron doping into diamond film can improve its conductivity and enhance its applications in electronic device, electrochemical and biomedical sensing devices. In the present study, boron doped diamond films were deposited on Si(100) using trimethylboron as a boron source by microwave plasma chemical vapour deposition with the B/C ratio in the gas mixture varying from 0 to 11 000 ppm. The boron doping resulted in the reduction in grain size of diamond and the increase in crystal imperfection. The number of twins in diamond grains increased for boron doped diamond films deposited at a high B/C ratio. Two new peaks at approximately 500 and 1220 cm⁻¹ resulted from Fano interference in Raman spectra were observed and dominated for heavily boron doped diamond film. Boron doping into diamond films improved their field electron emission properties and remarkably reduced the turn-on electric field. The low turn-on electric field of 15·3 V μm⁻¹ was achieved for boron doped diamond film deposited at B/C = 5600 ppm.

Keywords:

• Chemical vapour deposition
• Diamond film
• Boron doping
• Microstructure
• Field emission

This work was financially supported by the Natural Science Foundation of Jiangsu Province of China (grant no. BK2008419) and PhD Programs Foundation of the Ministry of Education of China for Young Teachers in University (grant no. 200802881003). Support from the NUST Research Funding (project no. ZDJH07) is also gratefully acknowledged.