Molecular Beam Epitaxial Growth Of InAs/AlSb 2DEG Structure

With the development of semiconductor industry technology,the device size of integrated circuits is getting smaller and smaller,and the density is getting higher and higher.Since the operating voltage does not decrease with the size of the device,serious heat dissipation problems are caused.Currently,the most widely used Si-based devices and circuits cannot fully meet the high performance requirements of different functional modules.One possible method to solve the above problems is to employ the high electron mobility materials into device fabrication process.Therefore,we will focus on devices with higher performance and circuit modules under the new material system.Among all possible new materials,Group III-V compound semiconductors are considered as one of the most promising materials.InAs/AlSb high electron mobility transistors are one of the most competitive devices in high speed,low power,and low noise applications.In order to solve the above problems,the epitaxy growth of InAs/AlSb HEMT material sample on GaAs SI substrate by MBE equipment is studied in this thesis.And this structure was transplanted onto Si substrate,and the InAs/AlSb quantum well structure was grown on Si substrate,which laid the foundation for the subsequent device fabrication and the research of heterogeneous integrated circuits.For the study of epitaxial growth of GaAs-based InAs/AlSb high electron mobility transistors,the following results are obtained:?1?Growth Temperature and V/III Ratio for the effect of the AlGaSb buffer layer,the optimum growth temperature and the optimal V/III ratio of the AlGaSb buffer layer were determined by a series of comparative experiments.?2?In InAs/AlSb quantum well growth experiments,thickness of InSb interface and AlSb isolation layer thickness in InAs and AlSb barrier layers were solved by comparative experiments.Atomic force microscopy?AFM?,X-ray diffraction?XRD?,Hall measurement and other measurements are involved.Finally,a material sample with an electron mobility of 20500 cm²/V·s,a carrier concentration of 2.3×10¹² cm^-2,and a surface RMS value of 1.27 nm was grown on a GaAs semi-insulating substrate.The production laid a solid foundation for the device fabrication.A 12%lattice mismatched InAs/AlSb quantum well structure was grown on a Si substrate with a[1 0 0]crystal orientation to[1 1 0]crystal orientation at a 4°tilt angle.The following results were obtained:?1?Using the two-step method,the electron mobility of a sample obtained by growing InAs directly on a Si substrate was 3600 cm²/V·s.By comparing the sample groups,it was found that the growth temperature of the second InAs had a greater influence on the overall quality of the material.It is considered that this is because the process of heating up to the growth temperature of the second layer of InAs is an annealing process for the first layer of InAs.This annealing process reduces the large lattice mismatch in the first layer of InAs.The introduction of penetrating dislocations gives a good base for the growth of the second layer of material.After adding the annealing step,the electron mobility of the grown InAs material was increased to 4640 cm²/V·s,which verified the above conjecture;?2?The structure of a GaAs-based InAs/AlSb high electron mobility transistor was grafted onto a Si substrate.Before growing the InAs/AlSb quantum well structure,an AlGaSb buffer layer is first grown.By introducing the AlGaSb buffer layer,a sample with an electron mobility of 5400 cm²/V·s was obtained,and the surface morphology of the sample was also improved.?3?Under the condition that the GaAsSb/AlGaSb buffer layer was introduced and the GaAs material was first grown on the surface of the Si substrate using the MEE growth method,an InAs material with an electron mobility of 10200 cm²/V·s was obtained.The heteroepitaxial III-V materials on Si provides a solid foundation for the hetero-integrated application.