An Empirical Potential Approach to Wurtzite–Zinc-Blende Polytypism in Group III–V Semiconductor Nanowires

Akiyama, Toru; Sano, Kazuhiro; Nakamura, Kohji; T, Ito

doi:10.1143/jjap.45.l275

Cited by 212 publications

(255 citation statements)

References 24 publications

(31 reference statements)

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“…In the case of GaAs, the critical radius under which wurtzite is expected to be the most stable phase lies between 5 and 25.5 nm, depending on the theory. [25][26][27] Other thermodynamic considerations relate the formation of wurtzite nanowires with a high supersaturation in the catalyst. As nanowires do not grow under thermodynamic equilibrium conditions, kinetic theories have also been used to understand the occurrence of wurtzite nanowires.…”

Section: Introductionmentioning

confidence: 99%

Structural and optical properties of high quality zinc-blende/wurtzite GaAs nanowire heterostructures

et al. 2009

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The structural and optical properties of three different kinds of GaAs nanowires with 100% zinc-blende structure and with an average of 30% and 70% wurtzite are presented. A variety of shorter and longer segments of zinc-blende or wurtzite crystal phases are observed by transmission electron microscopy in the nanowires. Sharp photoluminescence lines are observed with emission energies tuned from 1.515 eV down to 1.43 eV when the percentage of wurtzite is increased. The downward shift of the emission peaks can be understood by carrier confinement at the interfaces, in quantum wells and in random short period superlattices existent in these nanowires, assuming a staggered band offset between wurtzite and zinc-blende GaAs. The latter is confirmed also by time-resolved measurements. The extremely local nature of these optical transitions is evidenced also by cathodoluminescence measurements. Raman spectroscopy on single wires shows different strain conditions, depending on the wurtzite content which affects also the band alignments. Finally, the occurrence of the two crystallographic phases is discussed in thermodynamic terms.

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Section: Introductionmentioning

confidence: 99%

Structural and optical properties of high quality zinc-blende/wurtzite GaAs nanowire heterostructures

et al. 2009

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“…[1][2][3][4][5] One of the consequences related to the large surface-to-volume ratio is the crystallization of nanowires in crystalline structures that are not stable in the bulk form. [6][7][8][9][10][11] In the case of nanowires pertaining to the arsenides and phosphides, it is very common to find rotational twins along with polytypism between wurtzite and zinc-blende structures. Wurtzite is not stable in the bulk form of these compounds.…”

Section: Introductionmentioning

confidence: 99%

Raman spectroscopy of wurtzite and zinc-blende GaAs nanowires: Polarization dependence, selection rules, and strain effects

et al. 2009

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Polarization-dependent Raman scattering experiments realized on single GaAs nanowires with different percentages of zinc-blende and wurtzite structure are presented. The selection rules for the special case of nanowires are found and discussed. In the case of zinc-blende, the transversal optical mode E 1 ͑TO͒ at 267 cm −1 exhibits the highest intensity when the incident and analyzed polarization are parallel to the nanowire axis. This is a consequence of the nanowire geometry and dielectric mismatch with the environment, and in quite good agreement with the Raman selection rules. We also find a consistent splitting of 1 cm −1 of the E 1 ͑TO͒. The transversal optical mode related to the wurtzite structure, E 2 H , is measured between 254 and 256 cm −1 , depending on the wurtzite content. The azimuthal dependence of E 2 H indicates that the mode is excited with the highest efficiency when the incident and analyzed polarization are perpendicular to the nanowire axis, in agreement with the selection rules. The presence of strain between wurtzite and zinc-blende is analyzed by the relative shift of the E 1 ͑TO͒ and E 2 H modes. Finally, the influence of the surface roughness in the intensity of the longitudinal optical mode on ͕110͖ facets is presented.

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“…First, nucleation theories have been developed to investigate the appearance of wurtzite structure as a direction for obtaining pure crystal phases. [13][14][15][16] Second, the calculations of the energy parameters of the band structure of wurtzite GaAs and InP [17][18][19][20] have attracted a significant interest. Finally, the energy structure of the zinc-blende wurtzite heterojunction 8,9 and the piece-wise wurtzite phase material in the NWs 10,21,22 have been studied experimentally using photoluminescence (PL) spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

Valence band structure of polytypic zinc-blende/wurtzite GaAs nanowires probed by polarization-dependent photoluminescence

et al. 2012

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We conducted temperature-dependent measurements of the photoluminescence (PL) polarization on GaAs nanowires (NWs) with polytypic zinc-blende/wurtzite structure in order to probe the symmetry and energy structure of the valence band in the wurtzite segments of the NWs. The low-temperature measurements revealed that in most of the investigated cases, the ground level of the interface excitons responsible for the PL is formed by the heavy hole. To describe the observed temperature dependence of the degree of PL polarization, we developed a theoretical model that allows an estimation of the splitting between the heavy hole and light hole exciton subbands in these NWs. This splitting is smaller than expected in pure wurtzite on the basis of recent first-principles calculations, which may be attributed to the multiple twinned nature of the wurtzite sections, which effectively behave as a polytype of lower hexagonality.

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An Empirical Potential Approach to Wurtzite–Zinc-Blende Polytypism in Group III–V Semiconductor Nanowires

Cited by 212 publications

References 24 publications

Structural and optical properties of high quality zinc-blende/wurtzite GaAs nanowire heterostructures

Structural and optical properties of high quality zinc-blende/wurtzite GaAs nanowire heterostructures

Raman spectroscopy of wurtzite and zinc-blende GaAs nanowires: Polarization dependence, selection rules, and strain effects

Valence band structure of polytypic zinc-blende/wurtzite GaAs nanowires probed by polarization-dependent photoluminescence

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