Subhrajit Mukherjee | Technion - Israel Institute of Technology (original) (raw)

Uploads

Papers by Subhrajit Mukherjee

Physical Review Materials

Over the last few years, ReS2 has generated a myriad of unattended queries regarding its structur... more Over the last few years, ReS2 has generated a myriad of unattended queries regarding its structure, the concomitant thickness dependent electronic properties and its apparently contrasting experimental optical response. In this work, with elaborate first-principles investigations, using density functional theory (DFT) and time-dependent DFT (TDDFT), we identify the structure of ReS2, which is capable of reproducing and analyzing the layerdependent optical response. The theoretical results are further validated by an in-depth structural, chemical, optical and optoelectronic analysis of the large-area ReS2 thin films, grown by the chemical vapor deposition (CVD) process. Micro-Raman (MR), X-ray photoelectron spectroscopy (XPS), cross-sectional transmission electron microscopy (TEM) and energy-dispersive X-ray analysis (EDAX) have enabled the optimization of the uniform growth of the CVD films. The correlation between the optical and electronic properties was established by static photoluminescence (PL) and excited state transient absorption (TA) measurements. Sulfur vacancy-induced localized mid-gap states render a significantly long lifetime of the excitons in these films. The ionic gel top-gated photo-detectors, fabricated from the as-prepared CVD films, exhibit a large photo-response of ~ 5 A/W and a remarkable detectivity of ~ 10 11 Jones. The outcome of the present work will be useful in promoting the application of vertically grown large-area films in the field of optics and opto-electronics.

ACS Applied Materials & Interfaces, 2015

Nanoscale, Jan 7, 2014

We report the fabrication and optical response of boron-doped single silicon nanowire-based metal... more We report the fabrication and optical response of boron-doped single silicon nanowire-based metal-semiconductor-metal photodetector. Typical single nanowire devices with diameter of ∼80-100 nm and electrode spacing of ∼1 μm were made using electron-beam lithography from nanowires, grown by a metal-assisted chemical etching process. A high responsivity, of the order of 10(4) A W(-1), was observed even at zero bias in a single nanowire photodetector with peak responsivity in the near-infrared region. The responsivity was found to increase with increasing bias and decreasing nanowire diameter. Finite element based optical simulation was proposed to explain the diameter dependent performance of a single nanowire. The observed photoresponse is sensitive to the polarization of exciting light source, allowing the device to act as a polarization-dependent near-infrared photodetector.

npj 2D materials and applications, May 26, 2022

Stable ferroelectricity at room-temperature down to the monolayer limit, harnessed with strong se... more Stable ferroelectricity at room-temperature down to the monolayer limit, harnessed with strong sensitivity towards visible-to-nearinfrared illumination in α-In 2 Se 3, facilitates its potential as versatile building block for developing ultrathin multifunctional photonic integrated networks. Herein, we demonstrated a planar ferroelectric-semiconductor heterojunction (FeS-HJ) field-effect transistor (FET) fabricated out of α-In 2 Se 3 and In 2 O 3 , where the ferroelectric-polarization state in α-In 2 Se 3 is utilized to control the device characteristics. The robust in-plane (IP) polarization flipping triggered by out-of-plane (OOP) electrostatic field along with clear anticlockwise hysteresis loop were readily revealed by scanning Kelvin-probe force microscopy (KPFM) and electrical probing. The orthogonally tangled ferroelectric switching was used to manipulate the HJ channel conductance and thereby to realize nonvolatile memory (NVM) states. Moreover, gate-tuneable diode-like characteristics and superior photoresponse in HJ compared to its individual constitutes were observed. Utilizing the concurrent ferro-photonic coupling, high bandwidth optical inputs further tailored the outputs into four distinguished current states induced by different polarization directions. Our results pave the way for developing advanced (opto) electronic devices with diverse signal modulation capability to realize next generation low-power neurocomputing, brain-inspired visionary systems, and on-chip optical communications.

Israel Journal of Chemistry

The Journal of Physical Chemistry C

Tamm plasmon polaritons (TPPs) are excellent candidates for photonic device application for their... more Tamm plasmon polaritons (TPPs) are excellent candidates for photonic device application for their intriguing properties and simple fabrication design. In this study, optical Tamm structures are fabricated by depositing silver thin film on onedimensional photonic crystals (1DPhCs), constituting twelve pairs of alternating quarter wave thick SiO2 and TiO2 thin films. Carbon quantum dots (CQDs) were incorporated in the TiO2 matrix of the final four pairs of the 1DPhCs. TPPs are observed in the reflectance spectra of the samples with and without CQDs. With the help of transfer matrix method electric field intensity distribution profile is obtained. It is observed that the electric field is confined and enhanced at the metal-1DPhC interface and decays within the 1DPhC. Comparison of PL emission from samples with and without CQDs in the last four layers are presented. Enhanced PL emission from CQDs corresponding to the TPP mode and suppression of emission within the photonic stop band is ...

Journal- International Association for Shell and Spatial Structures, 2007

Telecommunication is increasing very rapidly in India. Large number of self-supporting microwave ... more Telecommunication is increasing very rapidly in India. Large number of self-supporting microwave towers are being constructed according to DOT (Department Of Telecommunication, Govt. of India) specification. The authors have designed large number of microwave towers according to DOT specification (rotation of antenna has been limited within ±0.5°). Due to transverse wind load the diagonal direction legs are subjected to maximum tension and maximum compression. Due to large compressive force, legs are subjected to differential settlement, which, in turn, will increase further rotation of tower. Authors feel that rotation of the tower should be calculated both for wind load assuming the base as rigid and due to differential settlement of legs assuming the soil as a compressible material. The present investigation comprised of an experimental study with a dimensional analysis. Based on the investigation the authors suggest that the value of permissible rotation as per DOT (±0.5°) shoul...

A simple fabrication of 2D photonic crystal with hexagonal lattice system of air-column in a high... more A simple fabrication of 2D photonic crystal with hexagonal lattice system of air-column in a high-dielectric medium based on 3D photolithography technique and interaction of quantum emitters embedded in a microcavity is presented.

We study transient absorption response of few-layered MoS2 nano-flakes in dispersion, mainly focu... more We study transient absorption response of few-layered MoS2 nano-flakes in dispersion, mainly focusing on its high energy exciton (commonly known as C exciton). We use a simple sono-chemical exfoliation technique to obtain confined nano-crystals of MoS2 of average diameter 2 nm, inter-dispersed in the flakes and study the effect of quantum confinement on this layered semiconductor. We emphasize on the interplay between exciton bleaching and excited state absorption upon a blue-detuned pumping. The relaxation times for the exciton are found and for the nano-crystals the radiative relaxation process is found to be slower as compared to that of the nano-flakes.

ACS Applied Materials & Interfaces

Interface of transition metal dichalcogenide (TMDC) and high-k dielectric transition metal oxides... more Interface of transition metal dichalcogenide (TMDC) and high-k dielectric transition metal oxides (TMO) had triggerred umpteen discourses due to the indubitable impact of TMO in reducing the contact resistances and restraining the Fermi-level pinning for the metal-TMDC contacts. In the present work, we focus on the unresolved tumults of large-area TMDC/TMO interfaces, grown by adopting different techniques. Here, on a pulsed laser deposited (PLD) MoS 2 thin film, a layer of TiO 2 is grown by using both atomic layer deposition (ALD) and PLD. These two different techniques emanate TiO 2 layers with different crystalline properties, thicknesses and interfacial morphologies, subsequently influencing the electronic and optical properties of the interfaces. In contrast to the earlier reports of n-type doping for exfoliated MoS 2 /TiO 2 interfaces, large-area MoS 2 /Anatase-TiO 2 films had demonstrated a ptype doping of the underneath MoS 2 , irrespective of the adopted deposition technique. In addition, they manifest a boost in the extent of p-type doping with increasing thickness of TiO 2 , as emerged after analyzing the core-level shifts of the X-ray photoelectron spectra (XPS). Density functional analysis of the MoS 2 /Anatase-TiO 2 interfaces, for pristine and in presence of a wide range of interfacial defects, could explain the interdependence of doping and the terminating atomic-surface of TiO 2 on MoS 2. The theoretical results resemble well with the realistic scenario of large-area growths after incorporating minimization of surfacestrain via mutual rotation of the constituent layers. The optical properties of the interface, encompassing the photoluminescence (PL), transient absorption and z-scan two-photon absorption indicate the presence of defect-induced localized mid-gap levels in MoS 2 /TiO 2 (PLD), resulting quenched exciton signals. On the contrary, the relatively defect-free interface in MoS 2 /TiO 2 (ALD) demonstrates a clear presence of both A and B excitons of MoS 2. This outcome corroborates with the first-principles observation of the presence of localized traps at the interfacial band-structure in presence of the point defects. From the investigation of optical properties, we indicate that MoS 2 /TiO 2 (PLD) interface may act as a promising saturable absorber, having a significant non-linear response for the sub-bandgap excitations. Moreover, MoS 2 /TiO 2 (PLD) interface had resulted a better photo-transport. A potential application of MoS 2 /TiO 2 (PLD) is demonstrated by the fabrication of a p-type photo-transistor with the ionic-gel top gate. This endeavor to analyse and understand the MoS 2 /TiO 2 interface establishes the prospectives of large-area interfaces in the field of optics and optoelectronics.

npj 2D Materials and Applications

The ability to couple the in-plane (IP) and out-of-plane (OOP) dipole polarizations in ferroelect... more The ability to couple the in-plane (IP) and out-of-plane (OOP) dipole polarizations in ferroelectric In2Se3 makes it a promising material for multimodal memory and optoelectronic applications. Herein, we experimentally demonstrate the cross-field optoelectronic modulation in In2Se3 based field-effect devices. Surface potential measurements of In2Se3 based devices directly reveal the bidirectional dipole locking following high gate voltage pulses. The experimental evidence of hysteretic change in the IP electrical field facilitating a nonvolatile memory switch, was further explored by performing photocurrent measurements. Fabricated photodetectors presented multilevel photocurrent characteristics showing promise for nonvolatile memory and electro-optical applications.

Two dimensional (2D) van der Waals heterostructures (vdWHs) have their unique potential in facili... more Two dimensional (2D) van der Waals heterostructures (vdWHs) have their unique potential in facilitating the stacking of layers of different 2D materials for optoelectronic devices with superior characteristics at a reduced cost. However, the fabrication of large area all-2D heterostructures is still challenging towards realizing practical devices. In the present work, we have demonstrated a rapid yet simple, impurity free and highly efficient sonication-assisted chemical exfoliation approach to synthesize hybrid vdWHs based on 2D molybdenum disulphide (MoS$_2$) and tungsten disulphide (WS$_2$), with high yield. Microscopic and spectroscopic studies have confirmed the successful exfoliation of layered 2D materials and formation of their hybrid heterostructure. The co-existence of 2D MoS2 and WS2 in the vdW hybrid is established by optical absorption and Raman shift measurements along with their chemical stiochiometry determined by X-ray photoelectron spectroscopy. The spectral respon...

Quantum Dot Photodetectors

ACS Applied Nano Materials

Advanced Optical Materials

ACS Applied Nano Materials

Physical Review Materials

Over the last few years, ReS2 has generated a myriad of unattended queries regarding its structur... more Over the last few years, ReS2 has generated a myriad of unattended queries regarding its structure, the concomitant thickness dependent electronic properties and its apparently contrasting experimental optical response. In this work, with elaborate first-principles investigations, using density functional theory (DFT) and time-dependent DFT (TDDFT), we identify the structure of ReS2, which is capable of reproducing and analyzing the layerdependent optical response. The theoretical results are further validated by an in-depth structural, chemical, optical and optoelectronic analysis of the large-area ReS2 thin films, grown by the chemical vapor deposition (CVD) process. Micro-Raman (MR), X-ray photoelectron spectroscopy (XPS), cross-sectional transmission electron microscopy (TEM) and energy-dispersive X-ray analysis (EDAX) have enabled the optimization of the uniform growth of the CVD films. The correlation between the optical and electronic properties was established by static photoluminescence (PL) and excited state transient absorption (TA) measurements. Sulfur vacancy-induced localized mid-gap states render a significantly long lifetime of the excitons in these films. The ionic gel top-gated photo-detectors, fabricated from the as-prepared CVD films, exhibit a large photo-response of ~ 5 A/W and a remarkable detectivity of ~ 10 11 Jones. The outcome of the present work will be useful in promoting the application of vertically grown large-area films in the field of optics and opto-electronics.

ACS Applied Materials & Interfaces, 2015

Nanoscale, Jan 7, 2014

We report the fabrication and optical response of boron-doped single silicon nanowire-based metal... more We report the fabrication and optical response of boron-doped single silicon nanowire-based metal-semiconductor-metal photodetector. Typical single nanowire devices with diameter of ∼80-100 nm and electrode spacing of ∼1 μm were made using electron-beam lithography from nanowires, grown by a metal-assisted chemical etching process. A high responsivity, of the order of 10(4) A W(-1), was observed even at zero bias in a single nanowire photodetector with peak responsivity in the near-infrared region. The responsivity was found to increase with increasing bias and decreasing nanowire diameter. Finite element based optical simulation was proposed to explain the diameter dependent performance of a single nanowire. The observed photoresponse is sensitive to the polarization of exciting light source, allowing the device to act as a polarization-dependent near-infrared photodetector.

npj 2D materials and applications, May 26, 2022

Stable ferroelectricity at room-temperature down to the monolayer limit, harnessed with strong se... more Stable ferroelectricity at room-temperature down to the monolayer limit, harnessed with strong sensitivity towards visible-to-nearinfrared illumination in α-In 2 Se 3, facilitates its potential as versatile building block for developing ultrathin multifunctional photonic integrated networks. Herein, we demonstrated a planar ferroelectric-semiconductor heterojunction (FeS-HJ) field-effect transistor (FET) fabricated out of α-In 2 Se 3 and In 2 O 3 , where the ferroelectric-polarization state in α-In 2 Se 3 is utilized to control the device characteristics. The robust in-plane (IP) polarization flipping triggered by out-of-plane (OOP) electrostatic field along with clear anticlockwise hysteresis loop were readily revealed by scanning Kelvin-probe force microscopy (KPFM) and electrical probing. The orthogonally tangled ferroelectric switching was used to manipulate the HJ channel conductance and thereby to realize nonvolatile memory (NVM) states. Moreover, gate-tuneable diode-like characteristics and superior photoresponse in HJ compared to its individual constitutes were observed. Utilizing the concurrent ferro-photonic coupling, high bandwidth optical inputs further tailored the outputs into four distinguished current states induced by different polarization directions. Our results pave the way for developing advanced (opto) electronic devices with diverse signal modulation capability to realize next generation low-power neurocomputing, brain-inspired visionary systems, and on-chip optical communications.

Israel Journal of Chemistry

The Journal of Physical Chemistry C

Tamm plasmon polaritons (TPPs) are excellent candidates for photonic device application for their... more Tamm plasmon polaritons (TPPs) are excellent candidates for photonic device application for their intriguing properties and simple fabrication design. In this study, optical Tamm structures are fabricated by depositing silver thin film on onedimensional photonic crystals (1DPhCs), constituting twelve pairs of alternating quarter wave thick SiO2 and TiO2 thin films. Carbon quantum dots (CQDs) were incorporated in the TiO2 matrix of the final four pairs of the 1DPhCs. TPPs are observed in the reflectance spectra of the samples with and without CQDs. With the help of transfer matrix method electric field intensity distribution profile is obtained. It is observed that the electric field is confined and enhanced at the metal-1DPhC interface and decays within the 1DPhC. Comparison of PL emission from samples with and without CQDs in the last four layers are presented. Enhanced PL emission from CQDs corresponding to the TPP mode and suppression of emission within the photonic stop band is ...

Journal- International Association for Shell and Spatial Structures, 2007

Telecommunication is increasing very rapidly in India. Large number of self-supporting microwave ... more Telecommunication is increasing very rapidly in India. Large number of self-supporting microwave towers are being constructed according to DOT (Department Of Telecommunication, Govt. of India) specification. The authors have designed large number of microwave towers according to DOT specification (rotation of antenna has been limited within ±0.5°). Due to transverse wind load the diagonal direction legs are subjected to maximum tension and maximum compression. Due to large compressive force, legs are subjected to differential settlement, which, in turn, will increase further rotation of tower. Authors feel that rotation of the tower should be calculated both for wind load assuming the base as rigid and due to differential settlement of legs assuming the soil as a compressible material. The present investigation comprised of an experimental study with a dimensional analysis. Based on the investigation the authors suggest that the value of permissible rotation as per DOT (±0.5°) shoul...

A simple fabrication of 2D photonic crystal with hexagonal lattice system of air-column in a high... more A simple fabrication of 2D photonic crystal with hexagonal lattice system of air-column in a high-dielectric medium based on 3D photolithography technique and interaction of quantum emitters embedded in a microcavity is presented.

We study transient absorption response of few-layered MoS2 nano-flakes in dispersion, mainly focu... more We study transient absorption response of few-layered MoS2 nano-flakes in dispersion, mainly focusing on its high energy exciton (commonly known as C exciton). We use a simple sono-chemical exfoliation technique to obtain confined nano-crystals of MoS2 of average diameter 2 nm, inter-dispersed in the flakes and study the effect of quantum confinement on this layered semiconductor. We emphasize on the interplay between exciton bleaching and excited state absorption upon a blue-detuned pumping. The relaxation times for the exciton are found and for the nano-crystals the radiative relaxation process is found to be slower as compared to that of the nano-flakes.

ACS Applied Materials & Interfaces

Interface of transition metal dichalcogenide (TMDC) and high-k dielectric transition metal oxides... more Interface of transition metal dichalcogenide (TMDC) and high-k dielectric transition metal oxides (TMO) had triggerred umpteen discourses due to the indubitable impact of TMO in reducing the contact resistances and restraining the Fermi-level pinning for the metal-TMDC contacts. In the present work, we focus on the unresolved tumults of large-area TMDC/TMO interfaces, grown by adopting different techniques. Here, on a pulsed laser deposited (PLD) MoS 2 thin film, a layer of TiO 2 is grown by using both atomic layer deposition (ALD) and PLD. These two different techniques emanate TiO 2 layers with different crystalline properties, thicknesses and interfacial morphologies, subsequently influencing the electronic and optical properties of the interfaces. In contrast to the earlier reports of n-type doping for exfoliated MoS 2 /TiO 2 interfaces, large-area MoS 2 /Anatase-TiO 2 films had demonstrated a ptype doping of the underneath MoS 2 , irrespective of the adopted deposition technique. In addition, they manifest a boost in the extent of p-type doping with increasing thickness of TiO 2 , as emerged after analyzing the core-level shifts of the X-ray photoelectron spectra (XPS). Density functional analysis of the MoS 2 /Anatase-TiO 2 interfaces, for pristine and in presence of a wide range of interfacial defects, could explain the interdependence of doping and the terminating atomic-surface of TiO 2 on MoS 2. The theoretical results resemble well with the realistic scenario of large-area growths after incorporating minimization of surfacestrain via mutual rotation of the constituent layers. The optical properties of the interface, encompassing the photoluminescence (PL), transient absorption and z-scan two-photon absorption indicate the presence of defect-induced localized mid-gap levels in MoS 2 /TiO 2 (PLD), resulting quenched exciton signals. On the contrary, the relatively defect-free interface in MoS 2 /TiO 2 (ALD) demonstrates a clear presence of both A and B excitons of MoS 2. This outcome corroborates with the first-principles observation of the presence of localized traps at the interfacial band-structure in presence of the point defects. From the investigation of optical properties, we indicate that MoS 2 /TiO 2 (PLD) interface may act as a promising saturable absorber, having a significant non-linear response for the sub-bandgap excitations. Moreover, MoS 2 /TiO 2 (PLD) interface had resulted a better photo-transport. A potential application of MoS 2 /TiO 2 (PLD) is demonstrated by the fabrication of a p-type photo-transistor with the ionic-gel top gate. This endeavor to analyse and understand the MoS 2 /TiO 2 interface establishes the prospectives of large-area interfaces in the field of optics and optoelectronics.

npj 2D Materials and Applications

The ability to couple the in-plane (IP) and out-of-plane (OOP) dipole polarizations in ferroelect... more The ability to couple the in-plane (IP) and out-of-plane (OOP) dipole polarizations in ferroelectric In2Se3 makes it a promising material for multimodal memory and optoelectronic applications. Herein, we experimentally demonstrate the cross-field optoelectronic modulation in In2Se3 based field-effect devices. Surface potential measurements of In2Se3 based devices directly reveal the bidirectional dipole locking following high gate voltage pulses. The experimental evidence of hysteretic change in the IP electrical field facilitating a nonvolatile memory switch, was further explored by performing photocurrent measurements. Fabricated photodetectors presented multilevel photocurrent characteristics showing promise for nonvolatile memory and electro-optical applications.

Two dimensional (2D) van der Waals heterostructures (vdWHs) have their unique potential in facili... more Two dimensional (2D) van der Waals heterostructures (vdWHs) have their unique potential in facilitating the stacking of layers of different 2D materials for optoelectronic devices with superior characteristics at a reduced cost. However, the fabrication of large area all-2D heterostructures is still challenging towards realizing practical devices. In the present work, we have demonstrated a rapid yet simple, impurity free and highly efficient sonication-assisted chemical exfoliation approach to synthesize hybrid vdWHs based on 2D molybdenum disulphide (MoS$_2$) and tungsten disulphide (WS$_2$), with high yield. Microscopic and spectroscopic studies have confirmed the successful exfoliation of layered 2D materials and formation of their hybrid heterostructure. The co-existence of 2D MoS2 and WS2 in the vdW hybrid is established by optical absorption and Raman shift measurements along with their chemical stiochiometry determined by X-ray photoelectron spectroscopy. The spectral respon...

Quantum Dot Photodetectors

ACS Applied Nano Materials

Advanced Optical Materials

ACS Applied Nano Materials