β-Ga₂O₃ Single Crystal Growth By EFG And Its Optical Properties Regulation

Semiconductor materials play an irreplaceable role in the modern information industrialization society,is the cornerstone of modern semiconductor industry and microelectronics industry,supporting the development of electronic information industry.At present,semiconductor materials have mainly experienced three generations of development.Diamond,β-Ga2O3,AIN,BN and other semiconductors with bandgaps larger than the 3.4eV bandgap of GaN are emerging as a new class of ultrawide-bandgap(UWBG)semiconductor materials.In recent years,β-Ga2O3 as a new generation of UWBG transparent semiconductor has attracted extensive attention from researchers in the fields of semiconductor,microelectronics and optoelectronics.The bandgap width of β-Ga2O3 is up to 4.8eV,which is much larger than traditional semiconductor materials,making it has outstanding advantages such as ultra-high breakdown field strength,ultra-large Baliga quality factor and short UV cut-off edge.It has developed rapidly in high voltage power devices,deep ultraviolet optoelectronic devices,and high brightness LED,etc,and has important application value in military,energy,medical,environment and other fields.The research and application of gallium oxide materials and devices is the research and competition focus of Germany,Japan,the United States and other countries.Recently,the basic research and industrialization of gallium oxide materials and devices have shown a remarkable momentum of accelerated development:the device performance keeps breaking record.The single crystal with high quality is in the front end of the UWBG semiconductor industry.It is the foundation of the whole gallium oxide industry in the future,and is the premise and foundation of semiconductor device manufacturing.Therefore,we focuse on the growth of β-Ga2O3 single crystal with high quality and large size,and aims to meet the practical application.The crystal growth process optimization and crystal quality characterization have been systematically studied.At the same time,we also explored the application of transition metal ion doped β-Ga2O3 crystal in the near infrared(NIR)spectroscopy.Ⅰ.Crystal growth,process optimization and device verification of β-Ga2O3 single crystalThe β-Ga2O3 crystal was grown by EFG method.By designing the growth die and improving the structure of the temperature field,the temperature suitable for the growth of β-Ga2O3 crystals with high melting point,volatile and strong absorption of infrared radiation was optimized.The more serious decomposition of Ga2O3 and crucible corrosion in the process of large crystal growth can be overcome effectively by designing dynamic crystal growth atmosphere.The 2-inch β-Ga2O3 single crystal was obtained by optimizing the process parameters such as crystal drawing speed,neck contracting and shoulder laying.And a vertical Schottky diode with an open resistance of 3 mΩ·cm,a switchi4g ratio of 108 at room temperature and an average breakdown field intensity of 2.1 mV/cm was fabricated using the grown,β-Ga2O3 single crystal as the substrate.Ⅱ.Crystal growth and the optical and electrical properties regulation property regulation of Mn2+doped β-G22O3The optical and electrical properties of β-Ga2O3 can be regulated,and its applications in the NIR spectroscopy can be expanded by doping the transition metal ion Mn2+.Mn2+:β-Ga2O3 crystal was first grown by EFG method,and its absorption spectra and CL spectra were characterized.Mn2+:β-Ga2O3 crystal has no obvious absorption in the infrared band,which proves its low carrier concentration.The CL spectrum half peak width is 120 nm,the maximum intensity at 700 nm,which proves that Mn2+:β-Ga2O3 crystal has excellent broadband NIR emission performance.Ⅲ.Crystal growth and the application in broadband NIR LED of Cr3+ dopedβ-Ga2O3The applications in the NIR spectroscopy can be expanded by doping the transition metal ion Cr3+.Cr3+:β-Ga2O3 crystal was grown by EFG method,and their absorption and fluorescence spectra were characterized.Cr3+:β-Ga2O3 crystal has two obvious absorption peaks near 423 nm and 589 nm.And the strong fluorescence peak is about 690nm.The conductivity of Cr3+:β-Ga2O3 crystal is n-type,the carrier concentration is 9.55×1017 cm-3,the carrier mobility is as high as 99.0 cm2c-1s-1,and the resistivity is only 66 mncm-1.In addition,we designed a new vertical structure broadband NIR LED based on Cr3+:β-Ga2O3 crystal due to its transparent conductivity,broadband NIR emission performance.