Pressure-induced metallic phase transition and elastic properties of indium phosphide III-V semiconductor
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Zhou Zheng Institute of Nuclear Physics and Chemistry, CAEP, Mianyang 621900, China (Received 29 October 2011; accepted 1 February 2012)
In this work, we find that the pressure-induced phase transition of InP from III-V semiconductor phase having zincblende (ZB) crystal structure to metallic phase having rocksalt (RS) structure occurs at a pressure of 8.56 GPa accompanied by an 18% volume collapse. It is found that the nearest In and P atoms bonded as covalent bond. Crystal space of ZB is just occupied by In-P tetrahedrons partly with many interstices, but that of RS is fulfilled by close-packed octahedrons entirely. With pressures, broadened energy band of antibonding state and the reduced density of states (DOS) of bonding state cause the weakening of tetrahedral In-P covalent bonds. And then, ZB is destroyed and rebuilt to RS structure. Some In-5s, In-5p, P-3p and a few P-3s move to unoccupied high energy level, across Fermi level, and migrate from valence band to conduction band, and then generate metallic properties. Furthermore, changes of covalent bond would cause evident variation of elastic properties on the {100} and {110} planes.
I. INTRODUCTION 1–3
For important applications in solar cells, optoelectronic devices4–7 and transferred electron devices,5 the III–V semiconductors, indium phosphide (InP) nanocrystals and nanowires are widely studied.8–11 The phase transition in solid state is one of the most important subjects in solid state physics, and has been discussed in relation to many systems. In the previous studies, it was found that InP has a semiconductor-to-metallic phase transition from zincblende (ZB) to rocksalt (RS) between 10 and 13.3 GPa.12–15 All of these results are experimentally confirmed with the phase transition pressures of about 10.0 GPa,16 10.8 GPa, 10.33 GPa17 and 10.5–11 GPa.12 Though experimental methods bring us the most objective results, the investigation of high-pressure-induced phase transition of III-V semiconductor compound is proliferative and there are many related factors such as electromagnetism, local thermal effect, etc.. DFT is another excellent theoretical method to study phase transition. Perhaps the greatest success of DFT18–24 has been its ability to predict the relative stability of semiconductor phases and determine the pressure at which these transitions occur.18–21 Within the last several years, phase diagrams of a number of solid state systems have been predicted. For example, pseudopotential solid state stability studies for silicon correctly predicted the pressure for a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2012.60 J. Mater. Res., Vol. 27, No. 8, Apr 28, 2012
the transition from diamond structure silicon to white tin (b-Sn) structure silicon. Theoretical studies based on total energy calculations25–29 have clearly predicted a firstorder phase transformation from the ZB structure to the RS structure under hydrostatic pressure. Meanwhile, Arbouche et al.30 studied the structural properties and phase stabil
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