Growth Of GaN Epilayer With The Novel Transition Layers Of Sputtered AlN And Graphene

GaN-based semiconductor materials are widely used in light-emitting diodes,laser diodes,and high electron mobility transistors due to their large bandgap,large breakdown-field strength,high saturation mobility,high irradiation resistance,and wide bandgap controllability.And other fields.However,at present,most of the GaN materials in applications are derived from heteroepitaxial growth,and there are bound to be higher density defects,and these defect densities always restrict the performance of GaN-based semiconductor devices.For more than 30 years people have been looking for ways to improve the crystal quality of GaN materials.However,almost all methods require an additional process flow,leading to a substantial increase in the cost of material preparation.Magnetron sputtering AlN nucleation layer technology has been widely used due to its low cost and obvious advantages of reducing dislocations.However,there are still many problems in its dislocation reduction mechanism and promotion in the field of electronic devices.On the other hand,graphene as the most representative two-dimensional material,its combination with nitride materials such as GaN can provide many possibilities for future development,such as the transfer of nitride epitaxial layer,enhance the thermal conductivity of electronic devices,Two-color detectors and so on.The basis of these applications is the preparation of GaN epitaxial materials with high crystalline quality and high resistance on graphene.However,there are still few related reports,especially the mechanism of its epitaxial growth need to be further studied.This article mainly focuses on the research of magnetron sputtering AlN nucleation layer and graphene transition layer and preparation of high-quality GaN materials.The AlN achievements are as follows:1.Based on magnetron sputtering AlN nucleation layer,a high quality GaN material was prepared,and its dislocation reduction mechanism was revealed.Compared to the conventional process of growing AlN nucleation layer by MOCVD,the dislocation density of GaN material based on magnetron sputtering AlN nucleation layer decreased by 76%.The characterization of the dislocations by TEM and other analyses revealed that the mechanism of dislocation reduction was due to the formation of faults that blocked the extension of dislocations,thereby reducing the density of dislocations.Further analysis revealed that the stacking faults were due to the dense and flat nucleation islands of magnetron sputtered AlN and the strong lateral growth mode of GaN growth.In addition,the growth mode can be controlled by adjusting the V/III ratio to suppress the occurrence of stacking faults,and a GaN material having a?002?plane FWHM of 35 arcsec is obtAlNed.This result is of great significance for the subsequent growth of GaN based on magnetron sputtering AlN nucleation layer and graphene.2.Innovatively propose"magnetron sputtering/MOCVD composite AlN transition layer structure",and successfully fabricate GaN materials with megohm level and high resistance properties based on this structure,and deeply study the effect of AlN insertion layer on impurity combination..It was found that when the V/III of the AlN insertion layer is relatively low,3-D growth mode is caused,which causes a large amount of impurities to be incorporated into the GaN material,and when the V/III ratio is too high,the GaN material is converted into an N-plane,resulting in The concentration of oxygen impurities rises dramatically,and both of these conditions cause background carrier concentration to increase.When the V/III ratio is moderate,GaN enters a two-dimensional step-flow growth mode,which reduces the ability of the impurity to bind and makes the GaN material obtain high resistance.3.Based on the"magnetron sputtering/MOCVD composite AlN transition layer structure",a buffer layer structure of AlN/GaN superlattice is proposed,and an AlGaN/GaN heterostructure with excellent electrical properties is successfully prepared.By optimizing the buffer layer structure,the diffusion of impurities into the interior of the GaN material is further suppressed,so that the concentrations of the three main impurities of silicon,oxygen,and carbon are all lower than 10¹⁷/cm3.The AlGaN/GaN heterojunction prepared on this epitaxial structure has excellent electrical properties.4.Based on van der Waals's epitaxial growth theory,unstressed GaN materials were successfully prepared on graphene.Through the gradual optimization of the epitaxy process:graphene preparation,nucleation layer structure,number of graphene layers,and GaN epitaxial layer structure,a stress-free GaN epitaxial material with high crystal quality and film-forming continuity was prepared.The?002?and?102?FWHM reached 811 and720 arcsec.5.A novel transition layer structure of AlN/graphene is proposed based on magnetron sputtering.By transferring the graphene on the substrate of the magnetron sputtering AlN nucleation layer,the crystal quality of the GaN material is greatly improved,the?002?and?102?FWHM reach 269 and 517 arcsec,and the surface roughness is 0.176 nm,and Has high resistance characteristics.Further studies have found that magnetron sputtering of AlN substrates is the key to achieving consistent crystal orientation in GaN materials.At the same time,the phenomenon of stacking fault dislocations in GaN reveals the cause of its lower dislocation density.In summary,this article has conducted comprehensive and in-depth research on structural design,material growth optimization,and characterization analysis of GaN material growth techniques based on magnetron sputtering of AlN and graphene transition layers.Based on magnetron sputtering AlN and GaN materials on graphene research level.The results obtained in this paper provide important guidance and reference for the subsequent research of optoelectronics and electronic devices.