Ex situ characterization techniques in molecular beam epitaxy(MBE)have inherent limitations,such as being prone to sample contamination and unstable surfaces during sample transfer from the MBE chamber.In recent years...Ex situ characterization techniques in molecular beam epitaxy(MBE)have inherent limitations,such as being prone to sample contamination and unstable surfaces during sample transfer from the MBE chamber.In recent years,the need for improved accuracy and reliability in measurement has driven the increasing adoption of in situ characterization techniques.These techniques,such as reflection high-energy electron diffraction,scanning tunneling microscopy,and X-ray photoelectron spectroscopy,allow direct observation of film growth processes in real time without exposing the sample to air,hence offering insights into the growth mechanisms of epitaxial films with controlled properties.By combining multiple in situ characterization techniques with MBE,researchers can better understand film growth processes,realizing novel materials with customized properties and extensive applications.This review aims to overview the benefits and achievements of in situ characterization techniques in MBE and their applications for material science research.In addition,through further analysis of these techniques regarding their challenges and potential solutions,particularly highlighting the assistance of machine learning to correlate in situ characterization with other material information,we hope to provide a guideline for future efforts in the development of novel monitoring and control schemes for MBE growth processes with improved material properties.展开更多
We report molecular beam epitaxial growth and electrical and ultraviolet light emitting properties of(AlN)m/(GaN)n superlattices(SLs),where m and n represent the numbers of monolayers.Clear satellite peaks observed in...We report molecular beam epitaxial growth and electrical and ultraviolet light emitting properties of(AlN)m/(GaN)n superlattices(SLs),where m and n represent the numbers of monolayers.Clear satellite peaks observed in XRD 2θ-ωscans and TEM images evidence the formation of clear periodicity and atomically sharp interfaces.For(AlN)m/(GaN)n SLs with an average Al composition of 50%,we have obtained an electron density up to 4.48×10^(19)cm^(-3)and a resistivity of 0.002Ω·cm,and a hole density of 1.83×10^(18)cm^(-3)with a resistivity of 3.722Ω·cm,both at room temperature.Furthermore,the(AlN)m/(GaN)n SLs exhibit a blue shift for their photoluminescence peaks,from 403 nm to 318 nm as GaN is reduced from n=11 to n=4 MLs,reaching the challenging UVB wavelength range.The results demonstrate that the(AlN)m/(GaN)n SLs have the potential to enhance the conductivity and avoid the usual random alloy scattering of the high-Al-composition ternary AlGaN,making them promising functional components in both UVB emitter and AlGaN channel high electron mobility transistor applications.展开更多
基金supported by the National Key R&D Program of China(Grant No.2021YFB2206503)National Natural Science Foundation of China(Grant No.62274159)+1 种基金CAS Project for Young Scientists in Basic Research(Grant No.YSBR-056)the“Strategic Priority Research Program”of the Chinese Academy of Sciences(Grant No.XDB43010102).
文摘Ex situ characterization techniques in molecular beam epitaxy(MBE)have inherent limitations,such as being prone to sample contamination and unstable surfaces during sample transfer from the MBE chamber.In recent years,the need for improved accuracy and reliability in measurement has driven the increasing adoption of in situ characterization techniques.These techniques,such as reflection high-energy electron diffraction,scanning tunneling microscopy,and X-ray photoelectron spectroscopy,allow direct observation of film growth processes in real time without exposing the sample to air,hence offering insights into the growth mechanisms of epitaxial films with controlled properties.By combining multiple in situ characterization techniques with MBE,researchers can better understand film growth processes,realizing novel materials with customized properties and extensive applications.This review aims to overview the benefits and achievements of in situ characterization techniques in MBE and their applications for material science research.In addition,through further analysis of these techniques regarding their challenges and potential solutions,particularly highlighting the assistance of machine learning to correlate in situ characterization with other material information,we hope to provide a guideline for future efforts in the development of novel monitoring and control schemes for MBE growth processes with improved material properties.
基金Project supported by the National Key R&D Program of China(Grant No.2022YFB3605600)the National Natural Science Foundation of China(Grant No.61974065)+3 种基金the Key R&D Project of Jiangsu Province,China(Grant Nos.BE2020004-3 and BE2021026)Postdoctoral Fellowship Program of CPSF(Grant No.GZC20231098)the Jiangsu Special ProfessorshipCollaborative Innovation Center of Solid State Lighting and Energy-saving Electronics。
文摘We report molecular beam epitaxial growth and electrical and ultraviolet light emitting properties of(AlN)m/(GaN)n superlattices(SLs),where m and n represent the numbers of monolayers.Clear satellite peaks observed in XRD 2θ-ωscans and TEM images evidence the formation of clear periodicity and atomically sharp interfaces.For(AlN)m/(GaN)n SLs with an average Al composition of 50%,we have obtained an electron density up to 4.48×10^(19)cm^(-3)and a resistivity of 0.002Ω·cm,and a hole density of 1.83×10^(18)cm^(-3)with a resistivity of 3.722Ω·cm,both at room temperature.Furthermore,the(AlN)m/(GaN)n SLs exhibit a blue shift for their photoluminescence peaks,from 403 nm to 318 nm as GaN is reduced from n=11 to n=4 MLs,reaching the challenging UVB wavelength range.The results demonstrate that the(AlN)m/(GaN)n SLs have the potential to enhance the conductivity and avoid the usual random alloy scattering of the high-Al-composition ternary AlGaN,making them promising functional components in both UVB emitter and AlGaN channel high electron mobility transistor applications.
