“…The actual dots size is 100−200 nm (Figure a); therefore, it is reasonable to assume that they are partially relaxed due to plastic deformation, and the work function variations are determined mainly by the composition changes. Figure c shows a CPD difference of 100−120 mV between the dot and the GaSb substrate that match the calculated value, obtained by taking into account the electron affinity, band gap, and valence band offsets reported for these unstrained materials and summarized in Table . 2 UHV topography (a) and KPFM measurements (b) of InSb nanocrystals grown on GaSb substrate.…”
supporting
confidence: 78%
“…Figure shows that As, diffusing from the GaAs substrate, penetrates the dots; therefore, for a large enough uncapped dot, there is a gradual composition change from the As-rich InAs x Sb 1 - x region in the bottom of the dot to the Sb-rich InAs x Sb 1 - x at the top of the dot. The estimated work function difference between the two materials is 50 meV; − in such a case, we expect a gradual decrease of the CPD profile toward the center of the dot. However, the fact that the measured CPD profile in Figure c wiggles indicates that the composition change alone cannot account for such work function changes, as we show in detail below.…”
A key factor in improving quantum dots electrical properties and dots-based devices is the ability to control the crucial parameters of composition, doping, size, and strain distribution of the dots. We show that nanometer-scale work function measurements using ultrahigh vacuum Kelvin probe force microscopy is capable of measuring the strain and composition variations within and around individual QDs. This is accomplished by analyzing the detailed surface potential profiles in and around InSb/GaAs dots.
“…The actual dots size is 100−200 nm (Figure a); therefore, it is reasonable to assume that they are partially relaxed due to plastic deformation, and the work function variations are determined mainly by the composition changes. Figure c shows a CPD difference of 100−120 mV between the dot and the GaSb substrate that match the calculated value, obtained by taking into account the electron affinity, band gap, and valence band offsets reported for these unstrained materials and summarized in Table . 2 UHV topography (a) and KPFM measurements (b) of InSb nanocrystals grown on GaSb substrate.…”
supporting
confidence: 78%
“…Figure shows that As, diffusing from the GaAs substrate, penetrates the dots; therefore, for a large enough uncapped dot, there is a gradual composition change from the As-rich InAs x Sb 1 - x region in the bottom of the dot to the Sb-rich InAs x Sb 1 - x at the top of the dot. The estimated work function difference between the two materials is 50 meV; − in such a case, we expect a gradual decrease of the CPD profile toward the center of the dot. However, the fact that the measured CPD profile in Figure c wiggles indicates that the composition change alone cannot account for such work function changes, as we show in detail below.…”
A key factor in improving quantum dots electrical properties and dots-based devices is the ability to control the crucial parameters of composition, doping, size, and strain distribution of the dots. We show that nanometer-scale work function measurements using ultrahigh vacuum Kelvin probe force microscopy is capable of measuring the strain and composition variations within and around individual QDs. This is accomplished by analyzing the detailed surface potential profiles in and around InSb/GaAs dots.
“…A more precise technique uses a sacrificial layer between the substrate and film, which, upon removal, releases the thin film as a freestanding membrane. The sacrificial layer may be selectively melted (5) or etched (6,7) away. In systems where the target film preferentially absorbs light, the film region adjacent to the transparent substrate can be selectively vaporized with intense laser light, thus becoming the sacrificial layer (8)(9)(10)(11).…”
Section: Introductionmentioning
confidence: 99%
“…Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland,, WA 99352, USA 3. Department of Electrical and Computer Engineering, University of Minnesota, Twin Cities, Minneapolis, MN 55455, USA.4 Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA 5. Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99352, USA 6.…”
The epitaxial growth of functional oxides using a substrate with a graphene layer is a highly desirable method for improving structural quality and obtaining freestanding epitaxial nanomembranes for scientific study, applications, and economical reuse of substrates. However, the aggressive oxidizing conditions typically used in growing epitaxial oxides can damage graphene. Here, we demonstrate the successful use of hybrid molecular beam epitaxy for SrTiO
3
growth that does not require an independent oxygen source, thus avoiding graphene damage. This approach produces epitaxial films with self-regulating cation stoichiometry. Furthermore, the film (46-nm-thick SrTiO
3
) can be exfoliated and transferred to foreign substrates. These results open the door to future studies of previously unattainable freestanding oxide nanomembranes grown in an adsorption-controlled manner by hybrid molecular beam epitaxy. This approach has potentially important implications for the commercial application of perovskite oxides in flexible electronics and as a dielectric in van der Waals thin-film electronics.
“…Thus, a higher percentage of the electron hole pairs created by the incident light will be collected at the contacts of a solar cell or detector, resulting in higher conversion efficiencies for such devices on thin membranes (9). The semiconductor materials used in these applications must have long carrier lifetimes so that electron-hole pairs created by photons have time to migrate to the contacts where they can be collected.…”
Freestanding, single-crystal, semiconductor membranes with thicknesses in the range of a few tens of nanometers to tens of microns are of increasing technological interest today. Their applications range from high speed electronic devices to electromechanical devices and pressure sensors. This review paper identifies two general classes of techniques for producing such thin membranes: dissolution of single-crystal wafers, and direct growth of single-crystal membranes. Numerous specific techniques in each general class are discussed. The discussion of each technique includes a brief explanation of the reason why it works, a description of the actual experimental implementation, an analysis of the range of thickness that can be produced, and the crystalline and electrical quality of the membranes. Unusual difficulties with implementing a technique, or special advantages of a technique are also noted. Since this review is intended to aid in the selection of a technique for producing thin semiconductor membranes when one has a particular application in mind, note is made of those applications for which the membranes produced with each technique are particularly well suited. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 128.197.26.12 Downloaded on 2015-06-27 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 128.197.26.12 Downloaded on 2015-06-27 to IP
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