Abstract
Amorphous carbon (a-C) films are attracting considerable attention to due their large optical band gap (Eopt) range of 1–4 eV. But the hopping conducting mechanism of boron doping a-C (a-C:B) is still mysterious. To exploring the intrinsic reasons behind the semiconductor properties of a-C:B, in this work, the boron doping a-C (a-C:B) nano-film was prepared, and the growth rate and Eopt changing were analyzed by controlling the different experimental conditions of magnetron sputtering. A rapid deposition rate of 10.55 nm/min was obtained. The Eopt is reduced from 3.19 eV to 2.78 eV by improving the substrate temperature and sputtering power. The proportion of sp2/sp3 increasing was uncovered with narrowing the Eopt. The shrinking Eopt can be attributed to the fact that boron atoms act as a fluxing agent to promote carbon atoms to form sp2 hybridization at low energy. Furthermore, boron atoms can impede the formation of σ bonds in carbon atom sp3 hybridization by forming B–C bonds with high energy, and induce the sp3 hybridization transfer to sp2 hybridization. This work is significant to further study of amorphous semiconductor films.
Highlights
Semiconductor films are the most common form of amorphous carbon (a-C) films, owing to the superior mechanical, optical, and opto-electronic properties [1,2,3,4,5]
Nitrogen/phosphorus incorporate a-C is n-type semiconductor, and Eopt decreases from 2.5 eV to 1.6 eV
We propose the following reasons for this narrowing Eopt : (a) with lower energy, the boron atoms only act on weakly π bonds of sp2 hybridization in carbon atoms; boron atoms can’t react with carbon atoms, and boron atoms act as mixture in a-C:B films
Summary
Semiconductor films are the most common form of amorphous carbon (a-C) films, owing to the superior mechanical, optical, and opto-electronic properties [1,2,3,4,5]. The superior properties of a-C arise from adjustable Eopt , which can extend to visible light [8,9] This is an effective way to adjust the Eopt with doping boron, nitrogen and phosphorus [10], which can form n-type or p-type semiconductors [11,12]. Nitrogen/phosphorus incorporate a-C is n-type semiconductor, and Eopt decreases from 2.5 eV to 1.6 eV with increasing nitrogen content [11]. Boron doping in a-C negatively affects conductance due to the presence of boron atoms which are void of π electrons, which is detrimental to sp hybridization. The interconvert between sp and sp in a-C:B films were analyzed under different experimental conditions of increasing boron target power, carbon target power, substrate temperature, and working pressure. This work is significant in the development of new functional amorphous semiconductor films
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
