Optimal Growth Of InN Films On Sapphire Substrates

The progress of semiconductor science and technology affects the development of information technology and promotes the progress of human civilization.The development of human civilization will bring new demand and promote the emergence of new industries,which puts forward higher requirements for Innovative materials.The development and progress of semiconductor materials evolved under this background.III-V semiconductors are the focus of research in recent years.Ga N materials were first widely studied and first applied in blue LED,bringing a revolutionary breakthrough to human lighting technology.For InN materials,due to its low dissociation temperature,it will decompose above600?,and the lack of suitable substrate,it is difficult to prepare highquality InN materials.InN has been considered as a wide band gap semiconductor material for a long time.With the progress of epitaxial technology,it is found that its band gap value is only 0.7e V.InN has the highest migration speed and the smallest effective mass,which makes it have great application prospects in high-frequency and high-speed electronic components and new solar cells.In view of the difficulties in the preparation of high-quality InN films,the optimal growth of InN films on sapphire substrate is studied in this paper.Using RF plasma assisted molecular beam epitaxy equipment,this paper studied the effects of plasma source power and nitrogen flow rate on the characteristics of epitaxial InN buffer layer films on different substrates and sapphire nitriding processes,and the effects of nitrogen flow rate on the morphology and crystal quality of two-step epitaxial InN materials.After ultrasonic cleaning in the early stage,the surface impurities were removed,and then annealed at 600? for 30 minutes.Firstly,the effect of nitriding power on epitaxial InN buffer film during nitriding in sapphire nitriding process is studied.The results show that the surface of the sample is smoother and the film-forming characteristics are better when the plasma power is 400 W.Then,the effect of nitrogen flow rate on epitaxial InN buffer film was studied.The test results show that insufficient nitrogen flow may lead to poor nitriding effect and incomplete Al N film on the surface of sapphire,so that the lattice mismatch is large and the crystal quality is poor during the subsequent growth of InN layer.Then,a thin InN buffer layer is grown by two-step epitaxy on the basis of high-temperature annealing and substrate nitriding,and then highquality InN films are grown on this buffer layer film.In the process of epitaxial growth,the effects of different nitrogen flow rate on the characteristics of epitaxial InN films were studied.The results show that InN grows along the c-axis under the four conditions of nitrogen flow rate of 1.5 sccm,2 sccm,2.5 sccm and 3 sccm,respectively.However,when the nitrogen flow rate is lower than 2.5 sccm,due to the lack of active N atoms,the growth is uneven and the film cannot be formed;When the nitrogen flow rate is too large,it will increase the scattering of in atoms before reaching the substrate,resulting in the increase of dislocation density,the decrease of grain size and the deterioration of crystal quality.When the nitrogen flow is 2.5sccm ? The scanning half peak width is the narrowest and the crystal quality is the best.