Interplay between phonon confinement and Fano effect on Raman line shape for semiconductor nanostructures: Analytical study

Yogi, Priyanka; Saxena, Shailendra K.; Mishra, Suryakant; Mohan, Hari; Late, Ravikiran; Kumar, Vivek; Joshi, Bipin; Sagdeo, Pankaj R.; Kumar, Rajesh

doi:10.1016/j.ssc.2016.01.013

Cited by 46 publications

(52 citation statements)

References 35 publications

(39 reference statements)

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“…An increase in FWHM values is commonly observed in UTB regions. This phenomenon is partly explained by phonon confinement and Fano effects, which lead to broadening and the asymmetric shape of Raman spectra of UTB GOI layers [20,21]. However, the FWHM values of the present UTB GOI layers are significantly larger than the previous results.…”

Section: Resultscontrasting

confidence: 65%

Electrical Properties of Ultra-Thin Body (111) Ge-On-Insulator n-Channel MOSFETs Fabricated by Smart-Cut Process

Lim

Zhao

Sumita

et al. 2021

IEEE J. Electron Devices Soc.

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We have systematically examined electrical characteristics of ultra-thin body (UTB) (111) Ge-on-insulator (GOI) n-channel metal-oxide-semiconductor field-effect transistors (nMOSFETs) fabricated by the smart-cut process and have compared their electrical properties with those of (100) ones. The (111) GOI thickness was varied from 29.4 to 7.3 nm. The normal MOSFET operation of a 7.3 nm-thick (111)-oriented GOI nMOSFET has been demonstrated with a reasonable ON/OFF ratio of 10 4 . However, degradation in the effective electron mobility and subthreshold swing (SS) of the (111) GOI nMOSFETs with decreasing the GOI thickness (TGOI) was observed. Raman analyses and electrical characteristics of GOI nMOSFET under back-gate operation has suggested that a high interface state density at (111) GOI/buried oxide interfaces as well as low GOI film quality near the back interfaces can be an origin of this degradation of the electrical properties with thin body channels.Index Terms-Ge-on-insulator (GOI), smart-cut technology, (111) surface orientation, MOSFETs, ultra-thin body (UTB) I. INTRODUCTIONS conventional Si-based complementary metal-oxidesemiconductor (CMOS) devices have encountered with physical limitations of scaling down, Ge has been studied as an alternative channel material due to its high carrier mobility and compatibility with the conventional Si CMOS technology [1][2][3]. In scaling down Ge MOS devices, an ultra-thin body (UTB) GOI structure is essential for strong immunity against shortchannel effects [4][5][6]. Recently, GOI MOSFETs, which can be realized under low thermal budget, have become more attractive because of the applicability to 3-dimensional stacked CMOS, promising as a future CMOS platform [7,8]. Here, the further improvement in electrical characteristics of n-channel GOI MOSFETs is one of the main challenges in developing the GOI CMOS. Thus, technology boosters to realize highperformance UTB GOI nMOSFETs is strongly needed.In order to enhance the GOI nMOSFET performance, the surface orientation must be carefully taken into account because of the anisotropic carrier transport properties of Ge [9]. Here, the (111) surface orientation of Ge has lower effective mass Manuscript received February xx, 2021.

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Section: Resultscontrasting

confidence: 65%

Electrical Properties of Ultra-Thin Body (111) Ge-On-Insulator n-Channel MOSFETs Fabricated by Smart-Cut Process

Lim

Zhao

Sumita

et al. 2021

IEEE J. Electron Devices Soc.

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“…This may be due to both the quantum confined effect and Fano interaction. [ 27 ] The first is understood to originate from phonon scattering in nanocrystals (NS) whereas the second is related to electron‐phonon scattering in NS. [ 27 ] When the NS decreases in size, the number of phonons participating in Raman scattering increases and a broad asymmetric peak results.…”

Section: Resultsmentioning

confidence: 99%

“…[ 27 ] The first is understood to originate from phonon scattering in nanocrystals (NS) whereas the second is related to electron‐phonon scattering in NS. [ 27 ] When the NS decreases in size, the number of phonons participating in Raman scattering increases and a broad asymmetric peak results. Furthermore, according to Yogi et al, [ 27 ] the higher the Fano interaction the broader and more asymmetric the Raman peak.…”

Section: Resultsmentioning

confidence: 99%

“…[ 27 ] When the NS decreases in size, the number of phonons participating in Raman scattering increases and a broad asymmetric peak results. Furthermore, according to Yogi et al, [ 27 ] the higher the Fano interaction the broader and more asymmetric the Raman peak. Therefore, it is possible to speculate that the cleaning procedures adopted assisted the separation of BNNS agglomerates, which present layers of few nanometers in length (see ref.…”

Section: Resultsmentioning

confidence: 99%

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Surface Cleaning of 2D Materials: Boron Nitride Nanosheets (BNNS) and Exfoliated Graphite Nanoplatelets (GNP)

Guerra

McNally

2020

Adv Materials Inter

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and impurities using methodologies such as electrical current annealing, [5] thermal annealing/desorption, [6-12] washing with water, acids, bases, ethanol, [12-14] plasma treatment, [13] and etching of metals. [15] Electrical annealing is effective at cleaning the surfaces of 2D materials; however, it is very limited in that it can only treat small sample areas (few micrometer square). [5] Thermal annealing proved to be the most effective at removing the impurities from the surface of 2D materials; however, there are serious concerns with regard degradation of the 2D material as a function of time. Washing with acids/bases are not always desirable as they can alter surface chemistry and their use may negatively impact the environment. [15] The etching of metals procedure is too laborious and not readily suitable for large-scale applications. Almost without exception the top-down production of 2D materials requires the use of surfactants or dispersants (e.g., water, ionic liquids) to assist the exfoliation of some bulk material. By way of example, the pretreatment of BNNS and exfoliated graphite nanoplatelets (GNP) studied here contain trace water and surfactant (sodium cholate, SC), [16,17] mainly introduced during the exfoliation of the corresponding bulk materials (i.e., boron nitride and graphite) in a high pressure homogenizer. [18] Specifically, three cleaning procedures were adopted in an attempt to remove impurities (i.e., water and SC) from the surfaces of BNNS and GNP, namely washing with ethanol, water assisted-freeze drying, and freeze drying without addition of water. Ethanol (EtOH) was utilized as it can wash water away from the surface of the BNNS and GNP and interact with the ionic surfactant SC thus being removed. The freeze drying process was selected as the sublimation of iced-water from the surface of BNNS and GNP would ideally remove water and exfoliate the 2D material further. [19-23] Indeed, when ice sublimates, the layers and flakes surrounded by ice are pulled apart. Two specific procedures for freeze drying were realized; FD-(i)-freezing of a dispersion of BNNS or GNP in water in liquid nitrogen followed by freeze drying and FD-(ii)-freezing in liquid nitrogen of the as received BNNS or GNP powder followed by freeze drying. The latter was performed on the basis that the water present as impurity in the BNNS and GNP samples would be sufficient at creating an ice pattern cutting through the layered structure Surface impurities such as water and surfactants can significantly affect the properties of 2D materials. They disrupt the 2D material lattice structure and surface chemistry and also promote electron and phonon scattering. Strategies to clean the surfaces of 2D materials are therefore critical to achieving optimal properties. Boron nitride nanosheets (BNNS) and exfoliated graphite nanoplatelets (GNP) are treated using three procedures: washing with ethanol, water-assisted freeze-drying, and freeze-drying without addition of water in an attempt to remove two impurities-water and an ion...

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“…The above mentioned PCM allows one to incorporate various other effects, affecting the Raman scattering, by suitably modifying the Raman line-shape Eq. [12,[18][19][20]. As described earlier, the origin of the Raman line-shape equation is the relaxation in the zone-center phonon selection rule and confinement induced uncertainty in the wave vector of phonons.…”

Section: Introductionmentioning

confidence: 88%

Generalisation of phonon confinement model for interpretation of Raman line-shape from nano-silicon

Tanwar

Yogi

Lambora

et al. 2017

Advances in Materials and Processing Technologies

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A comparative analysis of two Raman line-shape functions has been carried out to validate the true representation of experimentally observed Raman scattering data for semiconducting nanomaterials. A modified form of already existing phonon confinement model incorporates two basic considerations, phonon momentum conservation and shift in zone centre phonon frequency. After incorporation of the above mentioned two factors, a rather symmetric Raman line-shape is generated which is in contrary to the usual asymmetric Raman line-shapes obtained from nanostructured semiconductor. By fitting an experimentally observed Raman scattering data from silicon nanostructures, prepared by metal induced etching, it can be established that the Raman line-shape obtained within the framework of phonon confinement model is a true representative Raman line-shape of sufficiently low dimensions semiconductors.

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Interplay between phonon confinement and Fano effect on Raman line shape for semiconductor nanostructures: Analytical study

Cited by 46 publications

References 35 publications

Electrical Properties of Ultra-Thin Body (111) Ge-On-Insulator n-Channel MOSFETs Fabricated by Smart-Cut Process

Electrical Properties of Ultra-Thin Body (111) Ge-On-Insulator n-Channel MOSFETs Fabricated by Smart-Cut Process

Surface Cleaning of 2D Materials: Boron Nitride Nanosheets (BNNS) and Exfoliated Graphite Nanoplatelets (GNP)

Generalisation of phonon confinement model for interpretation of Raman line-shape from nano-silicon

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