Growth and Electrical Properties of Free-Standing Zinc Oxide Nanomembranes

Abstract

We report the synthesis of free-standing two-dimensional semiconductor zinc oxide (ZnO) nanomembranes (NMs) using a bottomup approach, i.e., nanomembranes grown from the faceted sidewalls of horizontally oriented ZnO nanowires (NWs). The ZnO NMs were synthesized on r-plane sapphire substrates utilizing high purity ZnO powder and graphite mixture and oxygen as source materials and argon (Ar) as carrier gas. Material characterization confirms that the horizontally oriented ZnO NWs were guided grown via a vapor−liquid−solid growth mechanism using gold as catalyst. The ZnO NMs were nucleated from the coated gold catalysts on the sidewalls of NWs. The electrical properties of the ZnO NMs were characterized based on a back-gate field effect transistor. The estimated carrier mobility of the ZnO NM is ∼150 cm 2 V −1 s −1 . The asgrown free-standing NMs can serve as the fundamental building blocks for a variety of applications in electronics and optoelectronics as well as sensing technologies. The unique bottom-up synthesis approach of the free-standing ZnO NMs is applicable for other material systems.

Synthesis and Structure-Dependent Optical Properties of ZnO Nanocomb and ZnO Nanoflag

“…With the deep development of the semiconductor industry, zinc oxide (ZnO) nanostructures with a wide direct band gap (3.37 eV) and a large exciton binding energy (60 meV) have attracted considerable attention due to their fascinating optoelectronic properties and great structural diversity. − ZnO nanostructures have exhibited extensive application in various industrial fields such as field effect transistors, − lasers, , photodetectors, − solar cells and batteries, and chemical and biological sensors. , During the past decades, ZnO nanostructures with plentiful morphologies, such as nanowires and needles, − nanosheets and nanodisks, tetrapod nanorods, nanomembranes, helix structures and nanobelts, have been successfully synthesized by various methods including chemical vapor deposition (CVD), solution synthesis, and hydrothermal method. ,, In particular, the CVD method is the most popular technique to prepare high quality crystalline structures. Among these CVD syntheses, most ZnO nanostructures have been grown through vapor–liquid–solid (VLS) mechanism with gold catalysts. , …”

“…1−5 ZnO nanostructures have exhibited extensive application in various industrial fields such as field effect transistors, 6−8 lasers, 9,10 photodetectors, 11−13 solar cells and batteries, 14 and chemical and biological sensors. 15,16 During the past decades, ZnO nanostructures with plentiful morphologies, such as nanowires and needles, 17−19 nanosheets and nanodisks, 20 tetrapod nanorods, 21 nanomembranes, 22 helix structures and nanobelts, 23 have been successfully synthesized by various methods including chemical vapor deposition (CVD), solution synthesis, and hydrothermal method. 17,24,25 In particular, the CVD method is the most popular technique to prepare high quality crystalline structures.…”

Nonlocal longitudinal vibration in a nanorod, a system theoretic analysis

“…The physics of micro-and nano-scale are fundamentally different from macro-scale. For example, carbon nanotubes have hollow structure [1], low density defect [2], high electrical and thermal conductivity [3], ZnO nanowires have wide band gap of 3.37 eV and an exciton binding energy of 60 meV [4] and boron nitride (BN) nanotubes are light in weight, stable at high temperatures, resistant to oxidation, and have outstanding thermal and electrical conductivity [5]. Nitrogen-doped carbon nanotube sponge can load capacity 100 times larger than its weight [6].…”

Flexible Organic/Inorganic Hybrid Field-Effect Transistors with High Performance and Operational Stability

“…23 Consequently, such 2D semiconducting nanomaterials have been employed for the realization of a number of exciting device applications such as field-effect transistors 23 photovoltaics 36,37 and piezoelectric nanogenerators 38,39 . Despite these several reports on the growth of NSs on sapphire substrates, [32][33][34] the exact mechanism responsible for the evolution of this type of nanostructure is still not well understood. In the present work, we have not only demonstrated exquisite growth of highly obliquely oriented single-crystalline ZnO NSs on rplane sapphire surface, but also decoded the growth mechanism behind the growth of such aligned nanostructures using characterization techniques such as x-ray diffraction (XRD) and cross-sectional high resolution transmission electron microscopy (HRTEM).…”

“…During the past decade, many efforts have been made to study the growth of well-ordered ZnO nanostructures such as nanowires (NWs) , and nanowalls. , Such aligned structures have proved to be advantageous, in both vertical and horizontal integration, for device fabrication over large areas. Recently, few nanometer thick two-dimensional (2D) ZnO nanosheets (NSs) , and/or nanomembranes (NMs) have gained much attention because of their high surface to volume ratio, reduced flexure rigidity, and superior electrical properties. Moreover, it was proposed that the surface of such a 2D nanomaterial sufficiently favors contacts that resemble those from conventional thin-film technologies, where the classical metal–semiconductor theory of planar contacts may be applied .…”