The Preparation And Optoelectrical Properties Of Be-,B-Ions-Implanted Gan And H-BN/GaN Heterojunction

Gallium nitride has become a key material for the development of high frequency,high power,high temperature,and radiation resistant semiconductor devices due to its characteristics of high breakdown electric field,good thermal conductivity,high electron saturation rate,and radiation resistance.However,from the preparation of basic materials to the realization of more complex device applications,a series of process treatments and structural designs are needed,among which doping and hetero-growth are two very important parts.As the structure of III-nitride devices becomes increasingly complex,a large number of structures requiring selective doping or transverse doping have been widely studied.The doping in conventional epitaxial growth cannot meet all the needs.The ion implantation doping method which can provide precise regional control becomes an important means to achieve such needs,and it is necessary to conduct in-depth research and understanding of it.At the same time,with the vigorous development of graphene materials,the application potential of the combination of two-dimensional layered materials with unique properties and mature film materials such as gallium nitride has been stimulated.Hexagonal boron nitride,which is the same groupⅢnitride as gallium nitride,is becoming the new focus of this development route.It has been developed and applied in many fields,such as field emission devices,high electron mobility transistors,light-emitting diodes,and ultraviolet photoelectric detectors.Given the above background,this project explores the changes in the structure and optical properties of gallium nitride caused by specific ion implantation.At the same time,high-quality hexagonal boron nitride was grown by direct epitaxy in gallium nitride materials,and high-performance photodetectors were prepared.In this study,beryllium ion implanted doped gallium nitride（Be-GaN）,boron ion implanted doped gallium nitride（B-GaN）,and hexagonal boron nitride/gallium nitride（h-BN/GaN）heterostructures were designed and prepared.The effects of material preparation methods on material qualityanddeviceperformancewerestudiedby various characterization methods,which laid a good foundation for their potential applications.The main contents and conclusions are as follows:（1）A series of studies have been carried out on gallium nitride materials doping through beryllium（Be）,boron（B）implantation,and rapid thermal annealing（RTA）process.Employing atomic force microscopy（AFM）,X-ray diffraction（XRD）,and Raman spectroscopy,two kinds of ion-implanted doped samples have been determined to have the best quality at 1100℃annealing temperature.The formation ofβ-phase beryllium nitride（β-Be₃N₂）grains was observed in several regions in Be-GaN by high-resolution transmission electron microscopy（HRTEM）,and the characteristic Raman vibration modes ofβ-Be₃N₂at 88 and 111 cm^-1were identified.In B-GaN,resonant Raman spectroscopy was used to reveal the optical transition from the band edge transition before doping to the in-band transition caused by impurity levels after doping.The dominant transition energy range was determined to be between 3.357～3.449 e V,and the impurity level location at39～131 me V which away from the band edge was calculated.The impurity activation energies of 116 me V and 66 me V in two temperature zones were obtained by fitting.In addition,in the experiment to study whether h-BN can be generated by increasing the injected ion dose,it is also found that B-GaN is more inclined to generate cubic boron nitride（c-BN）than h-BN by Raman results.（2）A series of studies have been carried out on the direct preparation of vertically standing hexagonal boron nitride（VO h-BN）on GaN epitaxial tablets by the SSVD process.The results show that the preconditioning method of the reaction precursor and the growth temperature has a great influence on the mass of VO h-BN,and the mechanism of limiting the hexagonal boron nitride epitaxial orientation by using the suspension bond slightly exposed on the GaN surface after high-temperature treatment was revealed by HRTEM.The photothermal Raman（OTR）test is also introduced to characterize the thermal conductivity of GaN or its heterogeneous epitaxial thin films,and the role of VO h-BN in enhancing the thermal management of GaN is discussed.（3）High-quality hexagonal boron nitride（FL h-BN）was directly grown by the PECVD process on GaN.The effects of substrate selection,optimal deposition temperature,RF power,and other process parameters on FL h-BN quality were discussed.The results show that the mass of hexagonal boron nitride is affected by the lattice constants and thermal expansion coefficient of different substrates.On the one hand,suitable plasma-assisted RF power can increase the active site on the GaN surface,and improve the deposition quality and deposition rate of h-BN.On the other hand,it can reduce the temperature required for deposition and reduce the surface damage of GaN caused by high temperatures.（4）Research was carried out on the preparation of deep ultraviolet photodetectors based on hexagonal boron nitride and gallium nitride heterostructure.The results show that the device has a maximum optical response of 3680 m A/W and a detection rate of 3.3×10¹³Jones at 280 nm wavelength light source,which is due to the p-n junction and the large gap width difference between them,which enhances the built electric field and reduces the dark current.In addition,the excellent in-plane carrier mobility and thermal management characteristics of the vertically standing hexagonal boron nitride make the detector have a fast response speed and can adapt to the operating conditions in high-temperature environments,and maintain good performance.In summary,based on the needs of the development of GaN-based materials and devices,this paper analyzes the structure and optical analysis of Be and B ion doping,which has been less studied before,and reveals its internal physical mechanism.On the other hand,the direct growth of h-BN on GaN is achieved,which helps to better combine 2D materials in combination with3D materials ofⅢ-nitride.