| The study of amorphous carbon(a-C)film has aroused much of attention in semiconductor film owing to its wide band gap.a-C has become a hot research because it has a wide application prospect in many fields.a-C possess a high resistivity due to there are the large amount of diamond-like sp3 hybridization in it,which limits their applications in semiconductor devices.Doped elements can improve the optical band gap of a-C from 4 to 1 e V,and improve the conductivity of a-C.Also,it can widely expand its application in practice.It has been reported that n-type semiconductor film can be fabricated with nitrogen/phosphorus doped a-C and p-type semiconductors film can be fabricated with boron doped a-C.Boron is one electron less than carbon,which can generate p-type doping in a-C.Although the structure of a-C is disordered in the long-range,the short-range can be regarded as the sp2 in the disordered sp3,which is mixture of sp2 and sp3.There is little studies about the boron incorporate a-C.The researchers mainly focus on changing the content of boron to modify the Eopt,but controlling the content and distributing the doped element are difficult.And there are lack of the explanations about improving the optical band gap thought experiment.Thus,it is important for the internal reason of doped semiconductor a-C to research the boron doping a-C which can modify the Eopt,and study its internal structure.In this work,a-C:B nano-films were prepared by magnetron sputtering to explore the influence of experiment conditions on the deposition rate and the Eopt of the a-C:B.And we get the following results.1.The influence of increasing boron target power,carbon target power,substrate temperature,and working pressure on the deposition rate were explored.The most superior growth rate is uncovered at 200 ?,1.0 Pa,the boron target power is 160 W and the carbon target power is 50 W.The fast deposition rate is 10.55 nm/min.2.The change of the Eopt was explored.The morphology of a-C:B film is granulated nano size about 30~80 nm based on SEM results.Based on the results of Raman,XPS,UV-vis ect.,we find the sythesized a-C:B film is an amorphous in XRD ect.We find that the Eopt of films are decrease with the increasing the boron target power,carbon target power and substrate temperature.The Eopt change from 3.19 e V to 2.78 e V.3.Based on the change of the Eopt,the reason that atom boron caused the band gap change of a-C:B film under the different external energies:(a)With lower energy,the boron atoms can only act on weak ? bonds in sp2 hybridization to destroy the free electrons.Hence,boron atoms act as mixture in a-C films with lower energy.(b)With higher energy,the boron atoms are able to act on ? bond in sp3 hybridization which transfer sp3 hybridization to sp2 hybridization.The intrinsic reason is that the ? bonds are weakest bonds,and ? bonds is stronger than ? bonds.This result is helpful to understand the doping mechanism in a-C and has important scientific significance for further study of amorphous films. |
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