Rajneesh Chaurasiya
@ncku.edu.tw
Post Doctoral Research Fellow at Material Science and Engineering
National Cheng Kung University Tainan Taiwan
EDUCATION
Ph.D. In Nanoelectronics
RESEARCH INTERESTS
Memory Devices, Gas sensor and solar cell
Scopus Publications
Scopus Publications
Dalip Kumar, Rajesh Kumar, and Rajneesh Chaurasiya
IOP Publishing
Abstract Janus monolayers based on transition metal dichalcogenides have garnered significant interest as potential materials for nano electronic device applications due to their exceptional physical and electronic properties. In this study, we investigate the stability of the Janus HfSSe monolayer using ab initio molecular dynamics simulations and analyze the electronic properties in its pristine state. We then examine the impact of adsorbing toxic gas molecules (AsH3, COCl2, NH3, NO2, and SO2) on the monolayer’s structure and electronic properties, testing their adsorption on different active sites on top of hafnium, selenium, and sulfur. The sensitivity of the gas molecules is quantified in terms of their adsorption energy, with the highest and lowest energies being observed for SO2 (−0.278 eV) and NO2 (−0.095 eV), respectively. Additionally, we calculate other properties such as recovery time, adsorption height, Bader charge, and charge difference density to determine the sensitivity and selectivity of the toxic gas molecules. Our findings suggest that the Janus HfSSe monolayer has the potential to function as SO2 and COCl2 gas sensor due to its high sensitivity for these two gases.
Sumit Kumar, Mirabbos Hojamberdiev, Anyesha Chakraborty, Rahul Mitra, Rajneesh Chaurasiya, Monika Kwoka, Chandra Sekhar Tiwary, Krishanu Biswas, and Mahesh Kumar
American Chemical Society (ACS)
Industrial emissions, environmental monitoring, and medical fields have put forward huge demands for high-performance and low power consumption sensors. Two-dimensional quasicrystal (2D QC) nanosheets of metallic multicomponent Al70Co10Fe5Ni10Cu5 have emerged as a promising material for gas sensors due to their excellent catalytic and electronic properties. Herein, we demonstrate highly sensitive and selective NO2 sensors developed by low-cost and scalable fabrication techniques using 2D QC nanosheets and α-Fe2O3 nanoparticles. The sensitivity (ΔR/R%) of the optimal amount of 2D QC nanosheet-loaded α-Fe2O3 sensor was 32%, which is significantly larger about 3.5 times than bare α-Fe2O3 sensors for 1 ppm of NO2 at 150 °C operating temperature. The sensors exhibited p-type conduction, and resistance was reduced when exposed to NO2, an oxidizing gas. The enhanced sensing characteristics are a result of the formation of nanoheterojunctions between 2D QC and α-Fe2O3, which improved the charge transport and provided a large sensing signal. In addition, the heterojunction sensor demonstrated excellent NO2 selectivity over other oxidizing and reducing gases. Furthermore, density functional theory calculation examines the adsorption energy and charge transfer between NO2 molecules on the α-Fe2O3(110) and QC/α-Fe2O3(110) heterostructure surfaces, which coincides well with the experimental results.
Bo-Ru Lai, Kuan-Ting Chen, Rajneesh Chaurasiya, Song-Xian You, Wen-Dung Hsu, and Jen-Sue Chen
Royal Society of Chemistry (RSC)
The proposed memristive device showcases nonlinear current responses and short-term memory behaviors, perfectly functioning as a physical reservoir with the capability to segregate 4-bit input signals and diverse temporal patterns.
Rajneesh Chaurasiya, Kuan‐Ting Chen, Li‐Chung Shih, Ya‐Chi Huang, and Jen‐Sue Chen
Wiley
AbstractMemory devices with sensitivity, selectivity, and operation voltage towards the gases are rarely reported for artificial olfactory sensors. Additionally, there are no reports available on the atomistic aspects of artificial olfactory sensors. This study reports an atomistic simulation of monoclinic‐ZrO2 (m‐ZrO2). The impact of external electric field on the formation of the oxygen vacancies are evaluated by considering the different directions of electric field. Furthermore, it is conducted nudged elastic band calculations which showed a decrease in the migration barrier energy with an increase in the electric field for all considered directions. Moreover, it is simulated the memristor device (Ta/m‐ZrO2/Pt) and investigated the impact of oxygen vacancies on electrical conductivity by considering oxygen vacancies at different locations in m‐ZrO2. Finally, it is evaluated the possibility of using the m‐ZrO2 based memristor device for an artificial olfactory sensor by studying the gas sensing properties of the (111) surface of m‐ZrO2. The pristine structure exhibits low sensitivity towards toxic molecules (CO2, CO, NH3, and NO2), while the sensing performance is significantly enhanced on the oxygen vacancy rich surface. These atomistic simulation results provide an atomic level understanding of the Ta/m‐ZrO2/Pt device and suggest the potential for it to be use as an artificial olfactory sensor.
Pei‐En Lin, Kuan‐Ting Chen, Rajneesh Chaurasiya, Hoang‐Hiep Le, Chia‐Hao Cheng, Darsen D. Lu, and Jen‐Sue Chen
Wiley
AbstractTo overcome the limitations of memristors in neuromorphic computation, memcapacitors are gaining attention owing to their scalability, low power dissipation, and sneak‐path‐free nature. This study focuses on the progressive capacitive switching of a bilayered metal‐oxide WOx/ZrOx heterojunction memcapacitor. To gain a better understanding of the interfacial switching behavior, density functional theory simulations are used to analyze the defects and oxide formation energy of the heterostructure. The memcapacitive characteristics are studied using the capacitance–voltage curves under different voltage‐sweeping conditions and impedance analysis. The memcapacitive characteristics can be attributed to the trapping of carriers in the depletion region of the WOx/ZrOx heterojunction, which is modulated by the relocation of oxygen vacancies under the electric field. The device exhibits a wider dynamic range of capacitance values than other metal‐oxide memcapacitors reported, and demonstrates versatile synaptic functions, such as potentiation/depression behavior, paired‐pulse facilitation, experience‐dependent plasticity, and learning–relearning behavior. Furthermore, an accuracy of 99.01% is achieved in handwritten digit classification using the capacitive state as the weight through a computing‐in‐memory emulator. The results affirm the applicability of the WOx/ZrOx memcapacitor in future capacitive neural networks.
Sumit Kumar, Mustaque A. Khan, Shashank Shekhar Mishra, Rajneesh Chaurasiya, Nipun Sharma, Meng Gang, Chandra S. Tiwary, Krishanu Biswas, and Mahesh Kumar
Royal Society of Chemistry (RSC)
The optimal amount of two-dimensional quasicrystal nanosheet decoration on 1T and 2H mixed-phase WS2 significantly enhances the NO2 sensing performance.
Rajneesh Chaurasiya, Li-Chung Shih, Kuan-Ting Chen, and Jen-Sue Chen
Elsevier BV
Abhijeet J. Kale, Rajneesh Chaurasiya, and Ambesh Dixit
Elsevier BV
Mohan Lal Meena, Sudipta Som, Rajneesh Chaurasiya, Shawn D. Lin, and Chung-Hsin Lu
Elsevier BV
Sumit Kumar, Rajneesh Chaurasiya, Shashank Shekhar Mishra, Partha Kumbhakar, Gang Meng, Chandra Sekhar Tiwary, Krishanu Biswas, and Mahesh Kumar
American Chemical Society (ACS)
Sumit Kumar, Rajneesh Chaurasiya, Mustaque A Khan, Gang Meng, Jen-Sue Chen, and Mahesh Kumar
IOP Publishing
Abstract We demonstrate a highly selective and sensitive Cupric oxide (CuO) thin film-based low concentration Hydrogen sulfide (H2S) sensor. The sensitivity was improved around three times by decorating with reduced graphene oxide (rGO) nanosheets. CuO thin films were deposited by Chemical Vapor Deposition followed by inter-digital electrode fabrication by a thermal evaporations system. The crystal structure of CuO was confirmed by x-ray diffraction. The sensing response of pristine CuO was found around 54% at 100 °C to 100 ppm of H2S. In contrast, the sensing response was enhanced to 167% by decorating with rGO of 1.5 mg ml−1 concentration solution. The sensing was improved due to the formation of heterojunctions between the rGO and CuO. The developed sensor was examined under various gas environments and found to be highly selective towards H2S gas. The improvement in sensing response has been attributed to increased hole concentration in CuO in the presence of rGO due to the Fermi level alignment and increased absorption of H2S molecules at the rGO/CuO heterojunction. Further, electronic structure calculations show the physisorption behavior of H2S molecules on the different adsorption sites. Detailed insight into the gas sensing mechanism is discussed based on experimental results and electronic structure calculations.
Shubham Tyagi, Rajneesh Chaurasiya, Nirpendra Singh, and Ambesh Dixit
Elsevier BV
Cheng-Han Lyu, Rajneesh Chaurasiya, Bo-Ru Lai, Kuan-Ting Chen, and Jen-Sue Chen
AIP Publishing
Gradual switching in the memristor or memcapacitor devices is the key parameter for the next generation of bio-inspired neuromorphic computing. Here, we have fabricated the WOx/ZrOx dual-oxide layered device, which shows the coexistence of gradual resistive and capacitive switching arisen from the current and capacitance hysteresis curves, respectively. The expansion of hysteresis loop can be modulated by altering the oxygen content in the oxide materials. Interestingly, the presence of negative differential resistance (NDR) is dependent on the voltage sweep direction and range of applied bias, which can be reasoned by the local electric field, charge trapping/detrapping, and conduction band offset at the dual-oxide interface. This study provides the concept of the coexistence of current and capacitance hysteresis along with NDR, and it is highly potential for memristor and memcapacitor circuits to explore neuromorphic computing.
Abhijeet J. Kale, Rajneesh Chaurasiya, and Ambesh Dixit
American Chemical Society (ACS)
Nilesh Kumar, Rajneesh Chaurasiya, Frantisek Karlicky, and Ambesh Dixit
IOP Publishing
Abstract We investigated the structural, thermodynamic, and optoelectronic properties of InxAl1−xN, InxGa1−xN, and GaxAl1−xN alloys for x = 0.25, 0.50 and 0.75. The optimized lattice constants showed nearly a small deviation trend from Vegard’s law with composition x. The impact of mutual alloying is evaluated in terms of enthalpy and interaction parameters. The calculated electronic band structures and density of states lie in the bandgap ranges from 1.09 eV to 2.72 eV for composition x 0.25 to 0.75. These electronic properties suggested that alloys are suitable bandgap semiconductors with large variations in their bandgap energies for optoelectronic applications. The optical properties are calculated using the dielectric constant and correlated with the calculated electronic band structures. The main reflectivity peak and absorption coefficient showed a significant shift with increasing x. These monolayers’ suitable bandgap and optoelectronic properties make them attractive for optoelectronic applications, including photovoltaics and photodetectors.
Rajneesh Chaurasiya, Pei-En Lin, Cheng-Han Lyu, Kuan-Ting Chen, Li-Chung Shih, and Jen-Sue Chen
IOP Publishing
Abstract Metal oxide ZrO2 has been widely explored for resistive switching application due to excellent properties like high ON/OFF ratio, superior data retention, and low operating voltage. However, the conduction mechanism at the atomistic level is still under debate. Therefore, we have performed comprehensive insights into the role of neutral and charged oxygen vacancies in conduction filament (CF) formation and rupture, which are demonstrated using the atomistic simulation based on density functional theory (DFT). Formation energy demonstrated that the fourfold coordinated oxygen vacancy is more stable. In addition, the electronic properties of the defect included supercell confirm the improvement in electrical conductivity due to the presence of additional energy states near Fermi energy. The CF formation and rupture using threefold and fourfold oxygen vacancies are demonstrated through cohesive energy, electron localization function, and band structure. Cohesive energy analysis confirms the cohesive nature of neutral oxygen vacancies while the isolated behavior for +2 charged oxygen vacancies in the CF. In addition, nudged elastic band calculation is also performed to analyze the oxygen vacancy diffusion energy under different paths. Moreover, we have computed the diffusion coefficient and drift velocity of oxygen vacancies to understand the CF. This DFT study described detailed insight into filamentary type resistive switching observed in the experimentally fabricated device. Therefore, this fundamental study provides the platform to explore the switching mechanism of other oxide materials used for memristor device application.
Chandra Prakash, Rajneesh Chaurasiya, Abhijeet J. Kale, and Ambesh Dixit
American Chemical Society (ACS)
We report the hydrogen-sensing response on low-cost-solution-derived ZnO nanorods (NRs) on a glass substrate, integrated with aluminum as interdigitated electrodes (IDEs). The hydrothermally grown ZnO NRs on ZnO seed-layer-glass substrates are vertically aligned and highly textured along the c-axis (002 plane) with texture coefficient ∼2.3. An optimal hydrogen-sensing response of about 21.46% is observed for 150 ppm at 150 °C, which is higher than the responses at 100 and 50 °C, which are ∼12.98 and ∼10.36%, respectively. This can be attributed to the large surface area of ∼14.51 m2/g and pore volume of ∼0.013 cm3/g, associated with NRs and related defects, especially oxygen vacancies in pristine ZnO nanorods. The selective nature is investigated with different oxidizing and reducing gases like NO2, CO, H2S, and NH3, showing relatively much lower ∼4.28, 3.42, 6.43, and 3.51% responses, respectively, at 50 °C for 50 ppm gas concentration. The impedance measurements also substantiate the same as the observed surface resistance is initially more than bulk, which reduces after introducing the hydrogen gas during sensing measurements. The humidity does not show any significant change in the hydrogen response, which is ∼20.5 ± 1.5% for a large humidity range (from 10 to 65%). More interestingly, the devices are robust against sensing response, showing no significant change after 10 months or even more.
Mohan Lal Meena, Sudipta Som, Rajneesh Chaurasiya, Shawn D. Lin, and Chung-Hsin Lu
Elsevier BV
Li-Chung Shih, Sheng-Rong Lin, Rajneesh Chaurasiya, Po-Yen Kung, Song-Syun Jhang, Bernard Haochih Liu, Yen-Hsun Su, and Jen-Sue Chen
Royal Society of Chemistry (RSC)
A photomemory based on a ZTO/Au NP heterostructure is revealed. It exhibits a broad spectral response and great retention to visible light due to the charge transfer at the ZTO/Au NP interface and surface plasmon resonance (SPR) of Au NPs.
Anupriya Singh, Rajneesh Chaurasiya, Amarnath Bheemaraju, Jen-Sue Chen, and Soumitra Satapathi
American Chemical Society (ACS)
Ching-Kang Shen, Rajneesh Chaurasiya, Kuan-Ting Chen, and Jen-Sue Chen
American Chemical Society (ACS)
Brain inspired artificial synapses are highly desirable for neuromorphic computing and are an alternative to a conventional computing system. Here, we report a simple and cost-effective ferroelectric capacitively coupled zinc-tin oxide (ZTO) thin-film transistor (TFT) topped with ferroelectric copolymer poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) for artificial synaptic devices. Ferroelectric dipoles enhance the charge trapping/detrapping effect in ZTO TFT, as confirmed by the transfer curve (ID-VG) analysis. This substantiates superior artificial synapse responses in ferroelectric-coupled ZTO TFT because the current potentiation and depression are individually improved. The ferroelectric-coupled ZTO TFT successfully emulates the essential features of the artificial synapse, including pair-pulsed facilitation (PPF) and potentiation/depression (P/D) characteristics. In addition, the device also mimics the memory consolidation behavior through intensified stimulation. This work demonstrates that the ferroelectric-coupled ZTO synaptic transistor possesses great potential as a hardware candidate for neuromorphic computing.
Mohan Lal Meena, Chung-Hsin Lu, Sudipta Som, Rajneesh Chaurasiya, and Shawn D. Lin
Elsevier BV
Somrita Dutta, Deepak Vishnu S. K, Sudipta Som, Rajneesh Chaurasiya, Dinesh Kumar Patel, Kalimuthu Moovendaran, Cheng-Chieh Lin, Chun-Wei Chen, and Raman Sankar
American Chemical Society (ACS)
Nilesh Kumar, Rajneesh Chaurasiya, and Ambesh Dixit
IOP Publishing
Abstract The thermodynamic stability of III-nitride monolayers is calculated using the phonon band structure. Electronic properties are computed using the generalized gradient approximation-Perdew–Burke–Ernzerhof exchange-correlation potentials, which show the semiconducting behavior with bandgap 0.59 eV, 2.034 eV, and 2.906 eV for InN, GaN, and AlN monolayers, respectively. The biaxial tensile and compressive strains are used as external stimuli to understand their impact on the optoelectronic properties of these monolayers. The thermodynamic stability of strained monolayers is investigated to explore the maximum possible strains, i.e. flexibility limit, these monolayers can sustain. These monolayers are more sensitive to compressive strains, showing thermodynamic instability even at 1% compressive strain for all the considered monolayers. Further, the III-nitride monolayers are more robust with the tensile strain. InN, GaN, and AlN monolayers can sustain up to 4%, 16%, and 18% tensile strain, respectively. More interestingly, the electronic transitions, such as direct to indirect and semiconducting to metallic, are noticed with strain in the considered monolayers. The optical properties also exhibit strong strain dependency at the different transition points.
Mohan Lal Meena, Sudipta Som, Chung-Hsin Lu, Rajneesh Chaurasiya, Somrita Dutta, Rajan Kumar Singh, and Shawn D. Lin
Elsevier