%0 Journal Article %1 Liu2009 %A Liu, Jefferson Zhe %A Zunger, Alex %D 2009 %J Journal of Physics: Condensed Matter %K alloys cubic nitrides order three_component %N 29 %P 295402 %R 10.1088/0953-8984/21/29/295402 %T Thermodynamic theory of epitaxial alloys: first-principles mixed-basis cluster expansion of (In, Ga)N alloy film %U http://stacks.iop.org/0953-8984/21/i=29/a=295402 %V 21 %X Epitaxial growth of semiconductor alloys onto a fixed substrate has become the method of choice to make high quality crystals. In the coherent epitaxial growth, the lattice mismatch between the alloy film and the substrate induces a particular form of strain, adding a strain energy term into the free energy of the alloy system. Such epitaxial strain energy can alter the thermodynamics of the alloy, leading to a different phase diagram and different atomic microstructures. In this paper, we present a general-purpose mixed-basis cluster expansion method to describe the thermodynamics of an epitaxial alloy, where the formation energy of a structure is expressed in terms of pair and many-body interactions. With a finite number of first-principles calculation inputs, our method can predict the energies of various atomic structures with an accuracy comparable to that of first-principles calculations themselves. Epitaxial (In, Ga)N zinc-blende alloy grown on GaN(001) substrate is taken as an example to demonstrate the details of the method. Two (210) superlattice structures, (InN) 2 /(GaN) 2 (at x = 0.50) and (InN) 4 /(GaN) 1 (at x = 0.80), are identified as the ground state structures, in contrast to the phase-separation behavior of the bulk alloy.

@article{Liu2009, abstract = {Epitaxial growth of semiconductor alloys onto a fixed substrate has become the method of choice to make high quality crystals. In the coherent epitaxial growth, the lattice mismatch between the alloy film and the substrate induces a particular form of strain, adding a strain energy term into the free energy of the alloy system. Such epitaxial strain energy can alter the thermodynamics of the alloy, leading to a different phase diagram and different atomic microstructures. In this paper, we present a general-purpose mixed-basis cluster expansion method to describe the thermodynamics of an epitaxial alloy, where the formation energy of a structure is expressed in terms of pair and many-body interactions. With a finite number of first-principles calculation inputs, our method can predict the energies of various atomic structures with an accuracy comparable to that of first-principles calculations themselves. Epitaxial (In, Ga)N zinc-blende alloy grown on GaN(001) substrate is taken as an example to demonstrate the details of the method. Two (210) superlattice structures, (InN) 2 /(GaN) 2 (at x = 0.50) and (InN) 4 /(GaN) 1 (at x = 0.80), are identified as the ground state structures, in contrast to the phase-separation behavior of the bulk alloy.}, added-at = {2011-01-07T16:54:53.000+0100}, author = {Liu, Jefferson Zhe and Zunger, Alex}, biburl = {https://www.bibsonomy.org/bibtex/240bc155bca8db88bb04049f37b481425/lopusz}, description = {Thermodynamic theory of epitaxial alloys: first-principles mixed-basis cluster expansion of (In, Ga)N alloy film}, doi = {10.1088/0953-8984/21/29/295402}, interhash = {205aa74db079accbfcb3673c0c96dbb6}, intrahash = {40bc155bca8db88bb04049f37b481425}, journal = {Journal of Physics: Condensed Matter}, keywords = {alloys cubic nitrides order three_component}, number = 29, pages = 295402, timestamp = {2011-10-15T22:54:17.000+0200}, title = {Thermodynamic theory of epitaxial alloys: first-principles mixed-basis cluster expansion of {(In, Ga)N} alloy film}, url = {http://stacks.iop.org/0953-8984/21/i=29/a=295402}, volume = 21, year = 2009 }