Tuning the Au‐Free InSb Nanocrystal Morphologies Grown by Patterned Metal–Organic Chemical Vapor Deposition

Abstract

4311www.MaterialsViews.com wileyonlinelibrary.com quantum physical phenomena and spinorbit systems. [18][19][20] Despite these attractive properties, advanced development in InSb-based technology has been diffi cult because of a lack of semi-insulating, lattice-matched substrates, and convoluted epitaxial constraints. Recent progress in nano-heteroepitaxy, however, has enabled high-quality III-V NPs to form on highly lattice-mismatched substrates. [ 3,21 ] This advancement opens the door for heterogeneous integration of high-performance InSb NP devices on cheaper and more readily available platforms.Exploration of InSb in the NP community is a growing research interest, with the fi rst reports appearing in 2005. InSb NPs have been grown using Au-assisted chemical beam epitaxy, [ 22,23 ] Au-catalyzed metal-organic chemical vapor deposition (MOCVD), [24][25][26] thermal CVD, [ 27 ] electrodeposition in porous templates, [ 28 ] and self-nucleation. [ 29 ] Almost all recently published methods are based on epitaxial techniques that generally use Au catalysts and an initial formation of InAs NP segments to assist the InSb NP formation. However, there has been evidence of Au atom contamination in the NPs using Au-catalyzed growth [ 30 ] ; Au is known to create recombination centers in III-V semiconductors. This can signifi cantly reduce the minority carrier lifetime and increase scattering, therefore hampering the device performance. Moreover, the necessity of using short InAs segments to assist InSb NP formation can further complicate practical device fabrication because of the large band-offset and type-III, broken-gap band alignment between InAs and InSb. [ 31 ] In this work, we provide a thorough study of direct InSb nanostructure formation on patterned InAs (111)B substrates, by MOCVD, without the use of Au catalysts and short InAs segments. We investigate various growth conditions that result in different types of InSb nanostructures, including the conditions required to achieve vertical NP growth. Our observations are then explained by fi rst-principles calculations using density-function theory (DFT). This paper provides a basic ground work for potential optoelectronic and electronic devices based on Au-free InSb NPs. MethodsInSb nanostructures are grown on patterned InAs (111)B substrates with a low-pressure (60 torr) vertical Emcore MOCVD reactor, using trimethylindium (TMIn) and trimethylantimony (TMSb) as precursors. The InAs substrates are patterned with A thorough study of direct InSb nanocrystal formations on patterned InAs (111)B substrates is provided. These nanostructures are created without the use of Au catalysts or initial InAs segments. Under the growth conditions generally used for selective-area, catalyst-free epitaxy, a wide range of InSb nanocrystal morphologies are observed. This is because the low-energy InSb surfaces, studied by fi rst-principles calculations, are the {111} facets as opposed to the {110} facets. By controlling the V/III ratio during growth, different InSb nanostructures can...

Free-Standing Two-Dimensional Single-Crystalline InSb Nanosheets

“…S7 and S8). As observed in InSb nanocrystals grown with a high Sb/In BEP ratio 26 , the side facets with low surface energy such as {111} and {011} can be clearly seen in our InSb nanosheets ( Fig. 2d, Supplementary Fig.…”

“…Although the stacking faults have been observed in Ag-catalyzed and selfseeded InSb nanowires by other groups, 24,25 detailed TEM observations of our grown InSb nanosheets with different shapes and sizes all reveal that the InSb nanosheets are fully single-crystalline, completely free from stacking faults and twinning defects (see Supporting Information Figures S9 and S10). As observed in InSb nanocrystals grown with a high Sb/ In BEP ratio, 26 the side facets with low surface energy such as {1̅ 11} and {011} can be clearly seen in our InSb nanosheets (Figure 2d and Supporting Information Figure S9). High-angle annular dark-field scanning TEM (HAADF-STEM) and corresponding EDS line profiles (see Supporting Information Figure S11) show that the InAs/InSb heterostructures start as InAs and then change to InSb.…”

Luminescent Colloidal InSb Quantum Dots from In Situ Generated Single-Source Precursor

“…Furthermore, this compound is characterized by crystallographic facets with low surface free energy and slow growth rates. 20 Additional challenges when growing InSb nanostructures by vapor-phase techniques are posed by the low vapor pressure and surface energy of antimony and its surfactant properties. 21 These challenges were nonetheless successfully addressed in the growth of InSb nanowires by metal organic vapor phase epitaxy (MOVPE), which has recently reached a very mature level, yielding arrays of high-quality, monodisperse, stemless InSb nanowires (diameter: 70–170 nm, length: 2–10 μm).…”

“…These requirements are particularly stringent for InSb, which is the most covalent of the III–V semiconductors. Furthermore, this compound is characterized by crystallographic facets with low surface free energy and slow growth rates . Additional challenges when growing InSb nanostructures by vapor-phase techniques are posed by the low vapor pressure and surface energy of antimony and its surfactant properties .…”

Luminescent Colloidal InSb Quantum Dots from In situ-Generated Single-Source Precursor

“…Furthermore, this compound is characterized by crystallographic facets with low surface free energy and slow growth rates. 20 Additional challenges when growing InSb nanostructures by vapor-phase techniques are posed by the low vapor pressure and surface energy of antimony and its surfactant properties. 21 These challenges were nonetheless successfully addressed in the growth of InSb nanowires by metal organic vapor phase epitaxy (MOVPE), which has recently reached a very mature level, yielding arrays of highquality, monodisperse, stemless InSb nanowires (diameter: 70−170 nm, length: 2−10 μm).…”