Electrical properties of polycrystalline and single crystalline nickel layer capped ZnO nanowires

Mudusu, D.,Nandanapalli, K.R.,Dugasani, S.R.,Kang, J.W.,Park, S.H.,Tu, C.W. Elsevier 2017 CURRENT APPLIED PHYSICS Vol.17 No.12

<P>This article reports the electrical characteristics of pristine, polycrystalline and single crystalline nickel (Ni) layer capped zinc oxide (ZnO) nanowires. Core/shell ZnO/Ni nanostructures were developed using chemical vapor deposition and e-beam evaporation, and the structures were annealed at different temperatures. Field effect transistor (FET) devices were fabricated using photolithography and investigated their characteristics at room temperature. All FET devices exhibited depletion-mode characteristics with n-type conductivity. However, single-crystalline Ni shelled ZnO nanowires based FET devices showed a high on/off ratio and transconductance, as compared to other devices. The overall measurements show that though the ZnO nanowires capped with Ni layer, their electrical properties remain same as pristine ZnO nanowires. (C) 2017 Elsevier B.V. All rights reserved.</P>

Electrical properties of polycrystalline and single crystalline nickel layer capped ZnO nanowires

Devika Mudusu,Koteeswara Reddy Nandanapalli,레디,강장원,박성하,CharlesW. Tu 한국물리학회 2017 Current Applied Physics Vol.17 No.12

This article reports the electrical characteristics of pristine, polycrystalline and single crystalline nickel (Ni) layer capped zinc oxide (ZnO) nanowires. Core/shell ZnO/Ni nanostructures were developed using chemical vapor deposition and e-beam evaporation, and the structures were annealed at different temperatures. Field effect transistor (FET) devices were fabricated using photolithography and investigated their characteristics at room temperature. All FET devices exhibited depletion-mode characteristics with n-type conductivity. However, single-crystalline Ni shelled ZnO nanowires based FET devices showed a high on/off ratio and transconductance, as compared to other devices. The overall measurements show that though the ZnO nanowires capped with Ni layer, their electrical properties remain same as pristine ZnO nanowires.

Development of tin (II) sulfide nanostructured films with uniform surface morphology by two-step growth process

Nandanapalli, Koteeswara Reddy,Mudusu, Devika,Lingandhinne, Raja Mohan Reddy,Mitta, Sekhar Babu,K. Reddy, Gunasekhar,Karuppannan, Ramesh,Whang, Dongmok Elsevier 2019 JOURNAL OF ALLOYS AND COMPOUNDS Vol.770 No.-

<P><B>Abstract</B></P> <P>Tin (II) sulfide (SnS), one of the most abundant materials, is being considered as an absorber material for the development of low-cost and nontoxic solar cell devices. In this direction, we have developed nanocrystalline films of SnS with uniform morphology on different substrates by adopting two-step thermal evaporation process. The surface studies show that irrespective of substrate nature, the as-grown SnS films possess uniform surface-morphology with well-defined facets. Structural studies reveal that SnS films grown on various substrates possess an orthorhombic crystal structure. However, as compared to other substrates, the structures developed on sapphire and copper exhibit ⟨010⟩ as preferential growth direction. From the electrical measurements, it is noticed that the films deposited on highly-conductive substrates consist of low electrical resistance, whereas the films are slightly resistive on insulating substrates. Based on these investigations it is emphasized that high-quality SnS films can be developed with uniform morphology on any substrates by adopting our two-step process.</P> <P><B>Highlights</B></P> <P> <UL> <LI> SnS films were developed with uniform morphology by using two-step process. </LI> <LI> The films grown on different substrates possess nanocrystallites with well-defined facets. </LI> <LI> These films consist of excellent chemical stoichiometry and phase purity. </LI> <LI> SnS films grown on different substrates have either ⟨111⟩ or ⟨010⟩ growth direction. </LI> </UL> </P>

Excellent enhancement in the device performance of nitrogen plasma treated ZnO nanorods based diodes

Reddy Nandanapalli Koteeswara,Devika Mudusu,한윤봉 나노기술연구협의회 2014 Nano Convergence Vol.1 No.26

Impact of the plasma exposure time on the physical properties of homo-epitaxial ZnO nanorods (NRs) and their devices was investigated. Here, ZnO NRs were synthesized by chemical solution method on glass substrates and treated under high intensity nitrogen plasma at different exposure timings. The as-grown as well as treated ZnO NRs exhibited hexagonal crystal structure and (001) as a preferential orientation. While increasing the plasma exposure time from 1 to 15 min, the structural and optical quality of ZnO NRs gradually improved and above this exposure time, both the properties degraded. The devices fabricated with 15 min plasma treated ZnO NRs showed excellent diode performance than the untreated nanostructures based devices. The diodes developed with treated ZnO NRs showed a low turn-on voltage (3.3 V) than the devices developed with untreated NRs.

Fabrication of Photovoltaic Devices Using ZnO Nanostructures and SnS Thin Films

N. Koteeswara Reddy,mudusu devika,K.R. Gunasekhar,E. S. R. Gopal 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.7

The development of nontoxic and cost-effective solar cell devices is one of the challenging tasks even now. With this objective, solar cell devices using tin mono sulfide (SnS) thin films and zinc oxide (ZnO) nanostructures with a superstrate configuration of ITO/ZnO film/ZnO nanorods/ SnS film/Zn have been fabricated and their photovoltaic properties have been investigated. Vertically aligned ZnO nanostructures were grown on indium doped tin oxide substrate by chemical solution method and then, SnS thin films were deposited by thermal evaporation method. A typical solar cell device exhibited significant light conversion efficiency with an open circuit voltage and short circuit current of 350 mV and 5.14 mA, respectively.

Functionalization of graphene layers and advancements in device applications

Nandanapalli, Koteeswara Reddy,Mudusu, Devika,Lee, Sungwon Elsevier 2019 Carbon Vol.152 No.-

<P><B>Abstract</B></P> <P>The invention of graphene, as a two-dimensional (2D) atomic layered material, has created enormous scientific revolutions in materials science. As a result, there are a variety of 2D materials came into limelight and intervening the existing technology. Today, one of the focusing issues in graphene technology is the development of functionalized (doped) graphene monolayers since the pristine graphene is chemically inert, hydrophobic and zero band gap material. As a result, the potential applications of graphene are limited to a few fields of science and technology. Surface functionalization, one of the typical approaches, is well-adopted for the development of functionalized graphene layers. In this scenario, we reviewed the latest advancements exclusively in the development of functionalized graphene layers, and exciting breakthroughs in graphene's science and technology. A brief history along with intrinsic properties of graphene is discussed in the introduction. Then, the methods adopted for the realization of functionalized graphene layers, and the impact of surface modification on their physical and chemical properties along with device performances are elaborately discussed. Finally, the review is summarized and outlined the perspectives of functionalized graphene layers in view of the development of multifunctional high-quality graphene layers for next-generation device applications.</P> <P><B>Graphical abstract</B></P> <P>This review discusses the importance of graphene functionalization, typical methodologies adopted for functionalizing the graphene layers or sheets, and advancements in the performance of graphene-based devices.</P> <P>[DISPLAY OMISSION]</P>

Si/ZnO heterostructures for efficient diode and water-splitting applications

Mitta, Sekhar Babu,Murahari, Prashantha,Nandanapalli, Koteeswara Reddy,Mudusu, Devika,Karuppannan, Ramesh,Whang, Dongmok Elsevier 2018 International journal of hydrogen energy Vol.43 No.33

<P><B>Abstract</B></P> <P>We have developed thin zinc oxide (ZnO) layers protected highly conductive p-type silicon (Si) electrodes and investigated their diode and photoanode characteristics. ZnO layers have been deposited on the glass as well as p-Si substrates at a temperature of 400 °C by pulsed spray pyrolysis method. The crystal structure, surface morphology, and phase purity of the layers along with electrical characteristics of the heterostructures were investigated. Finally, the photocatalytic water oxidation performance of the ZnO/Si structures was studied in an alkaline electrolyte solution (pH = 10). The as-grown devices exhibited excellent diode characteristics with a turn-on voltage of 4.5 V, and applied bias-voltage dependent carrier transport mechanisms. As compared to bare Si, ZnO coated Si-based PEC devices showed good stability and durability along with very low onset potential of 0.07 V versus Ag/AgCl.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Si/ZnO heterostructures are developed and investigated. </LI> <LI> Structures possess significant diode and PEC properties. </LI> <LI> As compared to bare Si, good photoanodes stability and durability are observed. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Ultrathin ZnO layers coated Si electrodes prepared by pulsed spray pyrolysis. These heterostructures exhibited excellent p-n junction diode characteristics along with good stability as well as durability as photoanodes in an alkaline electrolyte.</P> <P>[DISPLAY OMISSION]</P>

Poly-Trimethoxyphenylsilane as Carrier Film for Residual-Free CVD Graphene Transfer

Kim, Bum Jun,Shrivastava, Nilesh K.,Nasir, Tuqeer,Choi, Kyoung Soon,Lee, Jouhahn,Kim, Hak Chul,Kim, Kwan Woo,Devika, Mudusu,Lee, Sang Hoon,Jeong, Byung Joo,Yu, Hak Ki,Choi, Jae-Young Wiley - VCH Verlag GmbH & Co. KGaA 2017 Physica Status Solidi. Rapid Research Letters Vol.11 No.11