Search query: “Physical vapor deposition” and “Semiconductor nanomaterials”

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abstract: Abstract This work reports the first investigation on the physical vapor deposition of thin films of tin sulfide doped lead sulfide (SnS:PbS) In situ synthesis route using diethyldithiocarbamate (DTC) ligand was adopted for SnS DTC, PbS DTC and SnS:PbS DTC complex formation. PbS DTC and SnS:PbS DTC expressed an average crystallite size of 30.98 and 29.74 nm, respectively shown by X ray diffraction (XRD) analysis. A face centered cubic geometry was revealed from XRD. Ultraviolet visible spectrophotometry expressed a direct and indirect band gap of 3.4 and 3.2 eV, respectively for SnS:PbS DTC. A smooth morphology with presence of larger agglomerated particles was disclosed by scanning electron microscopy for SnS:PbS DTC thin films with 615 nm thickness. SnS:PbS DTC thin films expressed remarkable electrochemical behavior explored via cyclic voltammetry, linear sweep voltammetry and chronoamperometry showing an improvement in the photo current response upon potential bias increment. The results of the current research indicated the potential of SnS:PbS DTC thin films for utilization in different types of photovoltaic devices. Graphical Abstract
author_names: Aimen Zafar

Khuram Shahzad Ahmad

Shaan Bibi Jaffri

Manzar Sohail
title: Physical vapor deposition of SnS:PbS dithiocarbamate chalcogenide semiconductor thin films: elucidation of optoelectronic and electrochemical features
year: 2020

abstract: Abstract Current work reports the diethyl ammonium dithiocarbamate based metallic chalcogenide semiconductor complexes of Ag2S (dtc)2 [where dtc dithiocarbamate] BaS (dtc)2 and Ba:Ag2S (dtc)2 in an in situ chemosynthetic route for first time. Current work is also the first investigation reporting the physical vapor deposition of pristine [Ag2S (dtc)2]/SnO2 and doped [Ba:Ag2S (dtc)2]/SnO2 thin films was carried out in a resistive heating unit. Synthesized complexes and thin films expressed remarkable crystalline, vibrational, optical, morphological and elemental compositional characteristics revealed from different analytical tools. X ray diffraction disclosed the acanthite type orientation for the pristine and doped thin films with average crystallite sizes of 43.23 and 38.11 nm, respectively. Fourier transform infra red spectroscopy supported a myriad of functional groups, bond types and molecular arrangements in the single source precursor synthesized complexes. The optical analysis via ultra violet visible spectrophotometry expressed an alleviation in the both direct and indirect bandgaps from 3.9 to 3.7 eV and 3.8 to 2.7 eV determined from Tauc's plot for the doped [Ba:Ag2S (dtc)2]/SnO2 thin films showing the tailoring power of barium doping. Tightly packed thin films with presence of agglomerated particles were expressed by microstructural analysis done via scanning electron microscopy. Elemental profiling and thin film thickness measurement via Rutherford back scattering spectrometry supported strong signals for Ag, S and Ba with film thickness of 275 nm acquired for [Ba:Ag2S (dtc)2]/SnO2 thin films. Profound electrochemical functionality was expressed by cyclic voltammetry, linear sweep voltammetry and chronoamperometry showing the suitability of fabricated films for a wide range of optoelectronic and photovoltaic devices. Current work can be extended to achieving further improvement in the optoelectronic aspects of the synthesized films before they can be practically used in different photovoltaic contraptions.
author_names: Khuram Shahzad Ahmad

Aimen Zafar

Shaan Bibi Jaffri

Muhammad Khalid Alamgir

Manzar Sohail

Rana Farhat Mehmood

Misbah ur Rehman

Daoud Ali
title: Chemosynthesis and physical vapor deposition of acanthite thin films: Characterization and electrochemistry explorationwe
year: 2020

abstract: Understanding how dipolar, non centrosymmetric organic semiconductors self assemble, nucleate, and crystallize is integral for designing new molecular solids with unique physical properties and light matter interactions. However, dipole dipole and van der Waals interactions compete to direct the assembly of these compounds, making it difficult to predict how solids are formed from individual molecules. Here, we investigate four small molecules (TpCPD, TpDCF, AcCPD, and AcDCF) possessing anisotropic, non planar structures and large dipole moments, and establish robust algorithms to control their molecular self assembly via simple physical vapor deposition. Each molecule contains a central polar moiety, consisting of either a cyclopentadienone (CPD, ca. 3.5 D dipole moment) or dicyanofulvene (DCF, ca. 7.0 D dipole moment) core, that is surrounded by either four twisted phenyl (Tp) groups or a fused aromatic (acenaphthene, Ac) ring system. We find that only molecules containing the fused ring system form 1D nanowires due to the stronger van der Waals associations of the long, planar acenaphthene moieties. We examine the kinetics of self assembly for AcDCF and create diverse 1D morphologies, including both curved and linear nanostructures. Finally, using conductive AFM (c AFM) measurements, we show that 1D AcDCF wires support higher current densities relative to randomly oriented clusters lacking long range order.
author_names: Kwang-Won Park

David W Bilger

Trisha L Andrew
title: 1D nanowires of non centrosymmetric molecular semiconductors grown by physical vapor deposition
year: 2020

abstract: Anisotropic materials, especially two dimensional (2D) layered materials formed by van der Waals force (vdW) with low symmetry, have become a scientific hot spot because their electrical, optical, and thermoelectric properties are highly polarization dependent. The 2D GeSe, a typical anisotropic layered orthorhombic structure and narrow bandgap (1.1 1.2 eV) semiconductor, potentially meets these demands. In this report, the ultrathin elongated hexagonal GeSe nanoplates were successfully synthesized by the rapid physical vapor deposition method developed here. The ultrathin elongated hexagonal GeSe nanoplates have a zigzag edge in the long edge and an armchair edge in the short edge. In addition, the typical Raman mode exhibited 90deg periodic vibration, having its maximum intensity between the zigzag direction or the zigzag and armchair direction, indicating an anisotropic electron phonon interaction. Furthermore, the field effect transistor devices based on the elongated hexagonal GeSe nanoplates were constructed and exhibited the p type semiconducting behavior with a high photoresponse characteriscs. Finally, the polarized sensitive photocurrent was identified, further revealing the intrinsically anisotropy of the GeSe nanoplate. The results illustrated here may give a useful guidance to synthesize the 2D layered anisotropic nanomaterials and further advance the development of the polarized photodetector.
author_names: Jinyang Liu

Yuhan Zhou

Yue Lin

Mingling Li

Hongbing Cai

Yichun Liang

Mengyu Liu

Zhigao Huang

Fachun Lai

Feng Huang

Weifeng Zheng
title: Anisotropic Photoresponse of the Ultrathin GeSe Nanoplates Grown by Rapid Physical Vapor Deposition.
venue: ACS applied materials interfaces
year: 2019

abstract: In this work, the effects of different extraction parameters on the particle size of the nanopowders extracted from titanium dioxide thin film samples were studied. These nanopowders were obtained by the conjunctional freezing assisted ultrasonic extraction method. Titanium dioxide thin films were different in their structures (anatase only, rutile only, and mixed phase) and their structural characteristics were determined. Results showed that extraction parameters such as freezing temperature, ultrasonic frequency, and application time are very effective in determining the nanoparticle size, which is very important for many applications and uses of highly pure nanomaterials and nanostructures.
author_names: Oday A Hammadi
title: Effects of Extraction Parameters on Particle Size of Titanium Dioxide Nanopowders Prepared by Physical Vapor Deposition Technique
venue: Plasmonics
year: 2020

abstract: Modified g C3N4 sheets (CNS) with a bandgap of 2.61 eV were fabricated through physical vapor deposition (PVD) of g C3N4. During the PVD process, a series of gaseous derivatives derived from pristine g C3N4 at 700 degC condense into CNS at low temperature <400 degC) As a result, CNS still retains a typical semiconductor structure (bandgap of 2.61 eV) while at the same time, CN and O H defect groups were introduced to its tri s triazine based structure.
author_names: Xiaohui Sun

Xianghui An

Sa Zhang

Zhongtao Li

Jing Zhang

W Wu

Mingbo Wu
title: Physical Vapor Deposition (PVD) A Method to Fabricate g C3N4 Sheet
year: 2019

abstract: Abstract Lead selenide (PbSe) is a new emerging semiconductor with layer dependent bandgap that has attracted much interest due to its high infrared response and good environmental stability. We have prepared large scale PbSe films with the area of 7 cm2 and thickness of 25 nm based on physical vapor deposition approach at 160degC. The PbSe films exhibit saturable absorption property at 1.55 mm and a polarization sensitive saturable absorber is obtained by growing PbSe on D shaped fiber. Single pulse with the duration of 490 fs is generated at the pump of 12 mW and the mode locking operation is maintained at the pump of 1500 mW, indicating the high damage threshold of the D shaped fiber based saturable absorber. Two polarization insensitive saturable absorbers are achieved by depositing PbSe on fiber facet and polyvinyl alcohol film, respectively. For fiber facet (polyvinyl alcohol film) based saturable absorber, the repetition rate of Q switched pulses increases from 8.6 (16.3) kHz to 45.4 (59.2) kHz while the duration decreases from 7.92 (12) ms to 2.06 (3.12) ms by tuning the pump from 15 mW to 90 (60) mW. Such large scale PbSe films possess features of low cost and high modulation ability, and can find important applications in infrared optical modulators and detectors.
author_names: Qun Gao

Hao Yang

Cuichen Hu

Zhiwen He

Hua Lu

Wending Zhang

Dong Mao

Ting Mei

Jianlin Zhao
title: Physical vapor deposition of large scale PbSe films and its applications in pulsed fiber lasers
year: 2019

abstract: Growth of gallium phosphide nanowires by vapor deposition of simple thermally evaporated inorganic precursors is generally accompanied by unintentional formation of thick oxide coating, which may compromise the optical and electrical properties of the nanowires. Controlling and eliminating this outer layer during thermal evaporation growth of GaP nanowires represents a barrier to simple and scalable preparation of this technologically important material. In this article, we systematically investigated the role of different parameters (temperature, hydrogen flow rate, and starting Ga/P ratio) in the synthesis of GaP nanowires, and mapped out the conditions for the growth of oxide layer free nanowires. Increase in temperature, hydrogen flow, and phosphorus concentration led to diminished oxide layer thickness and improved nanowire morphology. Long and straight nanowires with the near perfect stoichiometry and complete absence of oxide outer layer were obtained for 1050 degC, 100 sccm hydrogen flow rate, and Ga/P flux ratio of 0.5. In contrast to other reports, this work emphasizes the importance of introducing hydrogen flow and excess phosphorus, which provide for reducing environment and reduced rate of the reaction of Ga with O in the growth process, respectively. The ability to control dielectric medium around GaP NWs by controlling the formation of oxide overlayer was demonstrated by Raman spectroscopy. The results of this work demonstrate a full control of the multi parameter space in the simple, inexpensive, and scalable synthesis of GaP NWs, and may provide a guideline for rational improvement of the growth conditions for other types of semiconductor nanowires.
author_names: Yun-yan Wang

M S Hegde

Shuo Wei Chen

Penghui Yin

Pavle V Radovanovic
title: Control of the spontaneous formation of oxide overlayers on GaP nanowires grown by physical vapor deposition
year: 2018

abstract: Anisotropic layered semiconductors have attracted significant interest due to the huge possibility of bringing new functionalities to thermoelectric, electronic and optoelectronic devices. Currently, most reports on anisotropy have concentrated on black phosphorus and ReS2, less effort has been contributed to other layered materials. In this work, two dimensional (2D) orthorhombic SnS flakes on a large scale have been successfully synthesized via a simple physical vapor deposition method. Angle dependent Raman spectroscopy indicated that the orthorhombic SnS flakes possess a strong anisotropic Raman response. Under a parallel polarization configuration, the peak intensity of Ag (190.7 cm( 1) Raman mode reaches the maximum when incident light polarization is parallel to the armchair direction of the 2D SnS flakes, which strongly suggests that the Ag (190.7 cm( 1) mode can be used to determine the crystallographic orientation of the 2D SnS. In addition, temperature dependent Raman characterization confirmed that the 2D SnS flakes have a higher sensitivity to temperature than graphene, MoS2 and black phosphorus. These results are useful for the future studies of the optical and thermal properties of 2D orthorhombic SnS.
author_names: Jing Xia

Xuan-Ze Li

Xing Yi Huang

Nannan Mao

Dandan Zhu

Lei Wang

Hua Xu

Xiangmin Meng
title: Physical vapor deposition synthesis of two dimensional orthorhombic SnS flakes with strong angle/temperature dependent Raman responses.
venue: Nanoscale
year: 2016

abstract: DOI: 10.1002/admi.201801379 stretchable conductor is to disperse conductive 0D, 1D, and 2D nanomaterials onto soft elastomeric substrates. These include nanoparticles,[6 8] carbon nanotubes,[9 11] silver nanowires,[12 14] and graphene,[15 19] all of which have demonstrated high conductivity and large stretchability. Another method is based on geometry, where thin conductive layers with micro/nanoscale corrugated structure maintain conductivity by unbending during stretching. These structures can be induced by surface buckling[19 22] or self assembled patterns.[23] Our recent work has demonstrated that interference lithography and atomic layer deposition (ALD) can be used to create a freestanding nano accordion structure,[24,25] which can be simultaneously stretchable, conductive, and transparent. This approach allows precise control of the structure period, height, and thickness to allow independent design of material properties. However, this approach relies on ALD of the conductive film, which has high cost and long deposition time. The ability to obtain conformal thinfilm coating using a low cost process can facilitate scale up manufacturing and broad implementation of flexible electronics. ALD is a widely employed vapor phase technique, where two gas precursors are introduced in alternating cycles to create a self limited surface reaction.[26,27] Each cycle result in a single monolayer coating, allowing precise control of film thickness by using discrete cycles. Since the gas precursors can permeate within rough topography and deep pores, ALD has demonstrated conformal coating in high aspect ratio grating structures,[24,25] high density nanoscale features,[28,29] and 3D porous lattice.[30 34] However, ALD also has a number of drawbacks, such as long reaction time and expensive precursor gases, contributing to high process cost. Compared with physical vapor deposition (PVD) the selection of deposition material is also limited. Furthermore, metal ALD generally requires high synthesis temperature, which can be problematic for polymer surfaces or template structures. A more established alternative is PVD, which is one of the most widely used technique for precise deposition of thin films, including metals and a diverse range of organic/inorganic materials. Representing a class of techniques where the Physical vapor deposition (PVD) is a versatile thin film coating technique that can deposit a wide selection of inorganic materials at low cost. However, the process is based on line of sight transfer, which can lead to shadowing effects and limit film uniformity over nonplanar topographies. This work describes improving conformal PVD coating on polymer nanostructures by increasing surface energy using a thin oxide interlayer deposited by atomic layer deposition (ALD) The proposed ALD assisted PVD process allows conformal coating at low cost, and can be adopted for a wide variety of materials compatible with tradition PVD. Conformal gold films over nanostructures with 500 nm half pitch and aspect ratio up to 1.5 are demonstrated. The film uniformity is characterized using cross sectional electron microscopy, energy dispersive X ray spectroscopy, and electrical measurements, showing a clear improvement in coating uniformity with the oxide interlayer. This PVD process is then used to fabricate metallic nano accordion structures, which can be used for stretchable conductors. The demonstrated process can improve material selection and reduce process cost of conformal coating, which can find applications in integrated circuit manufacturing, stretchable electronics, and wearable sensors.
author_names: Joong-Hee Min

Yen Lin Chen

I Te Chen

Tianlei Sun

Dennis T Lee

Chengjun Li

Yong Zhu

Brendan T O'Connor

Gregory N Parsons

Chih-Hao Chang
title: Conformal Physical Vapor Deposition Assisted by Atomic Layer Deposition and Its Application for Stretchable Conductors
year: 2018