Phase stability of monolayer Si1-Ge alloys with a Dirac cone
Xiaoyang Ma1, Tong Yang1, Dechun Li2
1Department of Physics, National University of Singapore, 2 Science Drive 3, 117551, Singapore. phyfyp@nus.edu.sg.
Abstract:
The phase stability and electronic properties of two-dimensional Si1-xGex alloys are investigated via the first-principles method in combination with the cluster expansion and Monte Carlo simulations. The calculated composition-temperature phase diagram indicates that at low temperatures (below 200 K) monolayer Si1-xGex alloys energetically favor phase separation, whereas when the temperature is increased above 550 K, Si1-xGex alloys can be stabilized and thereby form solid solutions across the whole composition range. Special quasi-random structures were constructed to model the monolayer Si1-xGex. The Si1-xGex alloys are found to possess a robust Dirac cone against composition variation. These results provide a guideline for the experimental realization of Si1-xGex alloys and monolayer Si1-xGex alloys are believed to hold great potential for realization of applications in nanoelectronics and nano-optoelectronics.
Related Concept Videos
Valence Bond Theory
Types of Semiconductors
Semiconductors
Metals such as copper (Cu), zinc (Zn), or lead (Pb) have low resistivity and feature conduction bands that are either not fully occupied or overlap with the valence band, making a bandgap non-existent. This allows electrons in the highest energy levels of the valence band to easily transition to the conduction band upon gaining...
Biasing of Metal-Semiconductor Junctions
In Schottky junctions, where the semiconductor is n-type, applying a positive voltage to the metal relative to the semiconductor reduces its Fermi...
Fermi Level Dynamics
Electron affinity in semiconductors refers to the energy gap between the minimum of its conduction band and the vacuum level and it is a critical parameter in determining how easily a semiconductor can accept additional electrons.
The work...
Stability of Substituted Cyclohexanes
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...


