Raman scattering study of InAs nanowires under high pressure

Abstract

The pressure-dependent phonon modes of InAs nanowires have been investigated by Raman spectroscopy under high pressure up to ∼58 GPa. X-ray diffraction measurements show that InAs nanowires at 21 GPa exhibit a phase transition from a wurtzite to an orthorhombic crystal structure, with a corresponding drastic change in the first-order Raman spectra. In the low-pressure regime, a linear increase in phonon frequencies is observed, whereas splitting between longitudinal and transversal optical phonon modes decreases as a function of applied pressure. The calculated mode Grüneisen parameters and Born's transverse effective charge indicate that the wurtzite InAs nanowires exhibit a more covalent nature under compression.

Phonon dispersion and Raman spectra of wurtzite InAs under pressure

“…[10][11] which can be attributed the difference in context of the present spectrum being for bulk WZ-InAs. Another difference in our spectrum with the earlier experimental spectrum [10][11] is in the value of E 2 H mode. While our calculated E 2 H mode lies in between the TO and LO modes, same is having about 3 cm -1 lower value than TO mode [10].…”

“…However, an intermediate transition to tetragonal phase is suggested at 4.0 GPa based on the pressure dependent decrease of FWHM of TO* (TO + E 2 H) mode. In an another study of pressure dependent Raman scattering in WZ-InAs nanowires an indication of structural phase transition to orthorhombic phase is observed at 21 GPa from X-ray diffraction study [11]. This pressure is however quite larger than the observed phase transition value for ZB to rock salt phase transition in bulk InAs (7.0 GPa) [14].…”

“…This is mainly due to the modified traditional electronic band structure, high electron mobility and small electron effective mass of InAs and thus providing new opportunities for the optoelectronics, photovoltaic and solar cell based semiconducting industry. At ambient conditions, bulk III-V semiconductor materials including InAs exhibit zinc blende (ZB) structure, however, in recent studies it has been shown that wurtzite (WZ) phase which is otherwise not possible in bulk form of III-V semiconductors can exist in the nanoparticles and nanowires (NW) [2,[6][7][8][9][10][11]. WZ phase has been shown to exist in the case of InAs nanowires [8,[10][11].…”

“…At ambient conditions, bulk III-V semiconductor materials including InAs exhibit zinc blende (ZB) structure, however, in recent studies it has been shown that wurtzite (WZ) phase which is otherwise not possible in bulk form of III-V semiconductors can exist in the nanoparticles and nanowires (NW) [2,[6][7][8][9][10][11]. WZ phase has been shown to exist in the case of InAs nanowires [8,[10][11]. This is attributed to the formation of staking faults in the sequence of In-As bilayers during growth of [111] ZB nanowires [9].…”

“…Recently, high pressure Raman scattering experimental studies on InAs nanowires in WZ phase are reported [10][11]. The Raman scattering in general is a powerful technique to understand the vibrational properties of any material and hence is useful in studying the structural and optoelectronic properties and correlating them with each other not only in the case of bulk also at the nanoscale [12][13].…”