Publications by authors named "Sepideh Gorji Ghalamestani"

III-V ternary nanowires are interesting due to the possibility of modulating their physical and material properties by tuning their material composition. Amongst them InAs Sb nanowires are good candidates for applications such as Infrared detectors. However, this material has not been grown directly from substrates, in a large range of material compositions.

View Article and Find Full Text PDF

We here investigate the growth mechanism of Sn-seeded GaSb nanowires and demonstrate how the seed particle and its dynamics at the growth interface of the nanowire determine the polarity, as well as the formation of structural defects. We use aberration-corrected scanning transmission electron microscopy imaging methodologies to study the interrelationship between the structural properties, i.e.

View Article and Find Full Text PDF

Understanding of the electrical contact properties of semiconductor nanowire (NW) field-effect transistors (FETs) plays a crucial role in the use of semiconducting NWs as building blocks for future nanoelectronic devices and in the study of fundamental physics problems. Here, we report on a study of the contact properties of Ti/Au, a widely used contact metal combination, when contacting individual InSb NWs via both two-probe and four-probe transport measurements. We show that a Schottky barrier of height [Formula: see text] is present at the metal-InSb NW interfaces and its effective height is gate-tunable.

View Article and Find Full Text PDF

The particle-assisted epitaxial growth of antimonide-based nanowires has mainly been realized using gold as the seed material. However, the Au-seeded epitaxial growth of antimonide-based nanowires such as GaSb nanowires presents several challenges such as for example direct nucleation issues and crystal structure tuning. Therefore, it is of great importance to understand the role of seed material choice and properties in the growth behavior of antimonide-based nanowires to obtain a deeper understanding and a better control on their formation processes.

View Article and Find Full Text PDF

The epitaxial growth of antimonide-based nanowires has become an attractive subject due to their interesting properties required for various applications such as long-wavelength IR detectors. The studies conducted on antimonide-based nanowires indicate that they preferentially crystallize in the zinc blende (ZB) crystal structure rather than wurtzite (WZ), which is common in other III-V nanowire materials. Also, with the addition of small amounts of antimony to arsenide- and phosphide-based nanowires grown under conditions otherwise leading to WZ structure, the crystal structure of the resulting ternary nanowires favors the ZB phase.

View Article and Find Full Text PDF

We present a study of InAs/InSb heterostructured nanowires by X-ray photoemission spectroscopy (XPS), scanning tunneling microscopy (STM), and in-vacuum electrical measurements. Starting with pristine nanowires covered only by the native oxide formed through exposure to ambient air, we investigate the effect of atomic hydrogen cleaning on the surface chemistry and electrical performance. We find that clean and unreconstructed nanowire surfaces can be obtained simultaneously for both InSb and InAs by heating to 380 ± 20 °C under an H2 pressure 2 × 10(-6) mbar.

View Article and Find Full Text PDF

Antimonide-based nanowires represent an important new class of material with great promise for both fundamental physics studies and various device applications. We report a comprehensive study on understanding the growth behaviour of GaxIn1-xSb nanowires on GaAs substrates using Au nanoparticles. First, the effect of growth parameters on the morphology and composition of GaxIn1-xSb nanowires is extensively studied over the entire compositional range (from 3 to ~100% of In).

View Article and Find Full Text PDF
Article Synopsis
  • The study explores the growth of GaAs/GaAs(x)Sb(1-x) core-shell nanowires on Si(111) substrates using molecular beam epitaxy, focusing on varying the Sb-content in the shells from 10% to about 70%.
  • The growth process achieves successful integration of the GaAs core's crystal structure into the GaAs(x)Sb(1-x) shells, which are formed in both zinc blende (ZB) and wurtzite (WZ) crystal structures.
  • Results show morphological and structural characteristics that highlight a slower growth rate for the shells on WZ segments compared to ZB segments.
View Article and Find Full Text PDF

The Ga(x)In(1-x)Sb ternary system has many interesting material properties, such as high carrier mobilities and a tunable range of bandgaps in the infrared. Here we present the first report on the growth and compositional control of Ga(x)In(1-x)Sb material grown in the form of nanowires from Au seeded nanoparticles by metalorganic vapor phase epitaxy. The composition of the grown Ga(x)In(1-x)Sb nanowires is precisely controlled by tuning the growth parameters where x varies from 1 to ∼0.

View Article and Find Full Text PDF

We have studied the epitaxial growth of an InP shell on various pure InAs core nanowire crystal structures by metal-organic vapor phase epitaxy. The InP shell is grown on wurtzite (WZ), zinc-blende (ZB), and {111}- and {110}-type faceted ZB twin-plane superlattice (TSL) structures by tuning the InP shell growth parameters and controlling the shell thickness. The growth results, particularly on the WZ nanowires, show that homogeneous InP shell growth is promoted at relatively high temperatures (∼500 °C), but that the InAs nanowires decompose under the applied conditions.

View Article and Find Full Text PDF

This study presents a novel approach for indirect integration of InAs nanowires on 2'' Si substrates. We have investigated and developed epitaxial growth of InAs nanowires on 2'' Si substrates via the introduction of a thin yet high-quality InAs epitaxial layer grown by metalorganic vapor phase epitaxy. We demonstrate well-aligned nanowire growth including precise position and diameter control across the full wafer using very thin epitaxial layers (<300 nm).

View Article and Find Full Text PDF