The Study On Microstructure And Optical Properties Of Boron Nitride Thin Films

Boron nitride is an artificial III-V semiconductor material,and while hexagonal boron nitride functions as a good thermal conductor and insulator,it also matches the lattice of graphene so that it can serve as a substrate for graphene devices or Insulated gate materials have broad application prospects in the field of deep ultraviolet optoelectronic devices and high power microelectronic devices.Therefore,in recent years,the growth and preparation of high-quality hexagonal boron nitride films have become a research hotspot.However,due to the harsh growth conditions,it is difficult to obtain a uniform hexagonal boron nitride film with high purity and high crystallinity.In addition,there are few studies on the stability and microstructure of hexagonal boron nitride films prepared by physical vapor deposition.In this paper,hexagonal boron nitride thin films were prepared on Si(100)substrates by RF magnetron sputtering.The sputtering time,substrate temperature,and sputtering power,substrate negative bias and nitrogen-argon ratio in sputtering gas were changed respectively,then using Fourier infrared spectrometer,atomic force microscope,scanning electron microscope,X-ray photoelectron spectrometer and X-ray diffractometer and other equipment on the optical properties,crystal quality,morphology characteristics,and elemental composition of hexagonal boron nitride films,tested and characterized the influence of different process parameters on the performance of the hexagonal boron nitride film.The influence of various process parameters on the microstructure and optical properties of hexagonal boron nitride films was comprehensively analyzed.At last,we have prepared high quality hexagonal boron nitride film,the main work includes the following sections:1.Comparing the effects of different preparation processes on the stability of hexagonal boron nitride films:(1)The high temperature baking of the vacuum chamber can effectively improve the stability of the film samples,and they substantially does not occur deliquescence in the air in 72 hours;(2)Samples prepared by this method all have a high degree of c-axis preferred orientation with a characteristic peak peak at 26.8°.2.Change the target sputtering time(30 min to 120 min):(1)The intensity of the infrared characteristic peak of the film sample is getting bigger and bigger,and the quality of the crystallization is getting better and better.At the initial stage of sputtering,the hexagonal boron nitride film with c-axis perpendicular to the substrate is mainly formed;(2)the surface roughness of the film sample is getting larger and larger,and the height fluctuation of columnar particles is largest at 8.3 nm at 120 minutes;(3)The thickness of the film sample grows linearly,and the deposition rate is around 6 nm/min.3.Change the substrate deposition temperature(100 °C ~ 400 °C):(1)The halfwidth of the infrared characteristic peak of the film sample is getting smaller and smaller,and the crystallizing quality is enhanced;(2)Surface The roughness is getting larger and larger,the RMS value is 3.265 nm at 400 °C,and the height fluctuation of columnar particles reaches a maximum of 10.46 nm.4.Change the target's sputtering power(100 W ~ 300 W):(1)The intensity of the infrared characteristic peak of the film sample is getting bigger,and the quality of the crystal is getting better;(2)The columnar particles on the surface of the film are getting larger and larger.The height fluctuation reaches 12.66 nm and the roughness increases to 2.1 nm at 300 W.(3)The film thickness increases from 315.7 nm to 937.4 nm.At 300 W,the maximum deposition rate is 7.81 nm.5.Change the substrate's negative bias voltage(0 V to-150 V):(1)The intensity of the infrared characteristic peak of the sample increases first and then decreases,the best crystallization quality is at-45 V.At the same time,the position of the characteristic peak shifts toward high wave numbers,which indicates that the internal stress is getting larger;(2)The surface roughness of the film increases continuously,-150 V When the RMS value reached a maximum of 22.8 nm.When the negative bias was too large,the internal stress of the sample was too large,and the film showed delamination.6.Change the ratio of nitrogen to argon in the gas component(60:0 ~ 1:1):(1)The intensity of the infrared characteristic peak of the film sample is getting bigger,and the quality of the crystallization is getting better and better;(2)The surface roughness of the film is getting larger and larger with a maximum of 2.56 nm;(3)The thickness of the film sample increases first and then decreases,and when the ratio of nitrogen to argon is 1:3,get maximum rate is 6.76 nm.(4)The increase in the proportion of nitrogen in the sputtering gas helps to suppress the oxygen element content,and also balances the boron to nitrogen ratio in the film sample,making the stoichiometric ratio closer to 1: 1.