Abstract
Dislocations exhibit a number of exceptional electronic properties resulting in a significant increase in the drain current of MOSFETs if defined numbers of these defects are placed in the channel. Measurements on individual dislocations in Si refer to a supermetallic conductivity. A model of the electronic structure of dislocations is proposed based on experimental measurements and tight-binding simulations. It is shown that the high strain level on the dislocation core—exceeding 10 % or more—causes locally dramatic changes in the band structure and results in the formation of a quantum well along the dislocation line. This explains experimental findings (two-dimensional electron gas, single-electron transitions). The energy quantization within the quantum well is most important for supermetallic conductivity.
Highlights
Dislocations are one-dimensional crystal defects influencing many of the physical and mechanical properties of crystalline solids [1, 2]
Dislocations exhibit a number of exceptional electronic properties resulting in a significant increase in the drain current of metal–oxide–semiconductor field-effect transistors (MOSFETs) if defined numbers of these defects are placed in the channel
It is shown that the high strain level on the dislocation core—exceeding 10 % or more—causes locally dramatic changes in the band structure and results in the formation of a quantum well along the dislocation line
Summary
Dislocations are one-dimensional crystal defects influencing many of the physical and mechanical properties of crystalline solids [1, 2] The analysis of their electronic properties is of particular interest for semiconductor devices because dislocations detrimentally effect. In p-type silicon dislocations form channels for electrons with supermetallic conductivity which is about eight orders of magnitude higher than of the surrounding Si matrix [13] This exceptional property and their dimension (length of a few micrometers and a cross-sectional area of the defect core of about 1 nm2) characterize dislocations as native nanowires embedded in a perfect crystalline matrix. The present paper presents an experimental and theoretical description of the electronic properties of dislocations based on the strain in the dislocation core This allows us to explain the supermetallic behavior as well as deep levels proved by DLTS.
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