The Role of Strain in the Surface Structures of III-V Alloyed SemiconductorFilms.

Surface Reconstruction;Strain;MBE;STM;DFT;III-V Semiconductors;Materials Science and Engineering;Engineering;Materials Science and Engineering

Bickel, Jessica E.Van Der Ven, Anton ;

University of Michigan

关键词: Surface Reconstruction;    Strain;    MBE;    STM;    DFT;    III-V Semiconductors;    Materials Science and Engineering;    Engineering;    Materials Science and Engineering;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/75875/jebickel_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

As length scales continue to decrease, it is vital to understand the fundamental physical parameters governing surfaces and surface interactions.In semiconductors particularly, surface reconstructions are known to impact film growth, bulk atomic ordering and the development of interfacial structure, all of which can drastically impact device growth.While the parameters that determine surface reconstructions in homoepitaxially grown films are well known and understood, those that impact alloy film growth are less studied.This work examines the impact of strain on alloy surface reconstructions, using the III-V semiconductors as a model system for any covalently bonded crystal structure.The presence of surface reconstruction coexistence in both mixed cation and mixed anion systems suggests that localized strain fields on alloy surfaces stabilize elastic relaxation at boundaries, resulting in more complex surface structures than those seen on binary, unstrained films.Atomic size mismatch strain is shown to induce an ordering in alloyed surface reconstructions that is not seen in the non-alloyed constituent surfaces.Lattice mismatch strain is shown to both stabilize new reconstructions not common to the homoepitaxial system and to induce surface reconstruction coexistence on alloy surfaces.The supplied flux of material is shown to affect the kinetics of transformation between the two coexisting surface reconstructions and an incorporation model for material on the alloy surface is developed.The effects of strained surface reconstructions on subsequent film growth is explored and it is shown that identical films grown on two different surfaces have very different strain relaxation profiles, surface topographies and defect structures.The strain fields of surface reconstructions and defects are also shown to interact which may have an impact on the insertion of dislocations in these films.Combined together, this deep understanding of the role that alloy induced strain plays in surface reconstructions will lead to a more complete understanding of the properties which govern reconstructions in general, and also create the possibility of engineering specific reconstructions which will form more abrupt interfaces, inject specific types of defects, or act as surfaces for subsequent self-assembly.