SnO2: The most important base material for semiconducting metal oxide-based materials

Staerz, Anna; Suzuki, Toshiharu; Bârsan, Nicolae

doi:10.1016/b978-0-12-815924-8.00012-8

Cited by 10 publications

(10 citation statements)

References 87 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The isothermal response transients and the response of all the sensors at 200 °C (the optimal working temperature) are shown in Figure c,d. CNT-NiO(200) and CNT-SnO 2 (50) CSHS show typical p- and n-type sensing responses related to their intrinsic cations and anions deficiencies, respectively. ,,,,, The thickness of the NiO shell was fixed to 5.5–6.5 nm (200 ALD cycles) since it has already been optimized in our previous study . Noticeably, at this thickness which is similar to the Debye length, λ D , the whole layer participates in the resistance modulation and the sensing response is maximized .…”

Section: Results and Discussionmentioning

confidence: 99%

“…A series of well-defined hierarchical CSHS composed of CNT- n MOS, CNT- p MOS, and CNT- n MOS- p MOS and CNT- p MOS- n MOS prototypes (i.e., CNT-SnO 2 , CNT-NiO, CNT-SnO 2 -NiO, and CNT-NiO-SnO 2 ) are synthesized, and their gas sensing properties are studied toward hydrogen chosen as a model analyte. SnO 2 and NiO are chosen as representative and among the most employed n- and p-type MOS, and CNTs as model 1D conductive substrate (core). ,, Different thicknesses of the n,p MOS thin films are deposited using atomic layer deposition (ALD), the most suitable technique to deposit MOS films with an ångstrom-level thickness control onto high-aspect-ratio substrates such as CNTs. − Conformal and homogeneous thin films of SnO 2 and NiO with controlled thicknesses are deposited in an alternate fashion to clearly assign the type of sensing response to the p-NiO or n-SnO 2 , allowing us to elucidate the sensing mechanism and the role of the heterojunction.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Role of Heterojunctions of Core–Shell Heterostructures in Gas Sensing

Raza

Chio

Movlaee

et al. 2022

ACS Appl. Mater. Interfaces

Self Cite

View full text Add to dashboard Cite

Heterostructures made from metal oxide semiconductors (MOS) are fundamental for the development of high-performance gas sensors. Since their importance in real applications, a thorough understanding of the transduction mechanism is vital, whether it is related to a heterojunction or simply to the shell and core materials. A better understanding of the sensing response of heterostructured nanomaterials requires the engineering of heterojunctions with well-defined core and shell layers. Here, we introduce a series of prototypes CNT-nMOS, CNT-pMOS, CNT-pMOS- n MOS, and CNT- n MOS-pMOS hierarchical core–shell heterostructures (CSHS) permitting us to directly relate the sensing response to the MOS shell or to the p–n heterojunction. The carbon nanotubes are here used as highly conductive substrates permitting operation of the devices at relatively low temperature and are not involved in the sensing response. NiO and SnO2 are selected as representative p- and n-type MOS, respectively, and the response of a set of samples is studied toward hydrogen considered as model analyte. The CNT-n,pMOS CSHS exhibit response related to the n,pMOS-shell layer. On the other hand, the CNT-pMOS-nMOS and CNT-nMOS-pMOS CSHS show sensing responses, which in certain cases are governed by the heterojunctions between nMOS and pMOS and strongly depends on the thickness of the MOS layers. Due to the fundamental nature of this study, these findings are important for the development of next generation gas sensing devices.

show abstract

Section: Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Role of Heterojunctions of Core–Shell Heterostructures in Gas Sensing

Raza

Chio

Movlaee

et al. 2022

ACS Appl. Mater. Interfaces

Self Cite

View full text Add to dashboard Cite

show abstract

“…Assuming bandgaps of 3.6 eV for SnO sensors showed a typical p-(an increased in resistance induced by a reducing gas) and n-type (a decrease in resistance induced by a reducing gas) sensing response, respectively. 6,[26][27][28][29] The generally accepted gas sensing mechanism for MOS-based gas sensors is correlated with a change of electrical resistance/conductance of the system as a result of oxygen-mediated (chemisorbed oxygen species: O 2− , O 2 − and O − ) interaction of gaseous analytes to the surface of the sensing films. 27,[30][31] In the case of n-type MOS, the oxygen species absorbed onto the surface (by capturing electrons from the conduction band of n-type MOS) lead to the formation of an electron-depletion-layer (EDL) which induces an upward band bending and an increase in the electrical resistance of the system.…”

Section: S3mentioning

confidence: 99%

On the Role of Heterojunctions of Core-Shell Heterostructures in Gas Sensing

Raza

Chio

Movlaee

et al. 2021

Preprint

View full text Add to dashboard Cite

Heterostructures made from semiconducting metal oxides (SMOX) are fundamental for the development of high-performance gas sensors. Yet, despite the recognition of their importance in real applications, the understanding of the transduction mechanism either related to the heterojunction, or simply to the core and shell materials is still lacking. A better understanding of the sensing response of heterostructured nanomaterials requires the engineering of heterojunctions with well-defined core and shell layers. Here, we introduce a series of prototypes nSMOX-CNT, pSMOX-CNT, and pSMOX-nSMOX-CNT and nSMOX-pSMOX-CNT hierarchical core-shell heterostructures (CSHS) permitting us to directly relate the sensing response to the SMOX shell, or to the p-n heterojunction. The carbon nanotubes are here used as highly conductive substrates permitting to operate the devices at relatively low temperature and are not involved in the sensing response. NiO and SnO2 are selected as representative p- and n-type SMOX, respectively, and the response of a set of samples is studied toward hydrogen considered as model analyte. The n,pSMOX-CNT CSHS exhibit response related to the n,pSMOX-shell layer. On the other hand, the pSMOX-nSMOX-CNT and nSMOX-pSMOX-CNT CSHS show sensing responses, which in certain cases are governed by the heterojunctions between nSMOX and pSMOX and strongly depends on the thickness of the SMOX layers. Due to the fundamental nature of this study, these findings are important for the development of next generation gas sensing devices.

show abstract

“…Although research on the mechanisms involved at the MOX surface has been going on for decades, they remain not yet fully understood and there is disagreement on the molecular details in the scientific literature [11]. One of the major problems is that many studies are carried out in synthetic environments, and therefore, the results may not be compared with realistic (i.e., real world) sensing conditions [12]. In order to overcome this limitation, studies at in operando conditions were performed using multi-sensor arrangements [13].…”

Section: Mox-measurement For Real-time Quantification Of Organic Compounds (Ch 4 )mentioning

confidence: 99%

“…iHWGs are compatible with a wide variety of light sources including not only coupling to entire broad-band infrared spectrometers but also to latest IR light source technologies including interband cascade lasers (ICL) and quantum cascade lasers (QCL). Since their introduction in 2013, their unmatched versatility has rendered iHWGs a key component in a wide variety of gas sensing scenarios probing species including to date 12…”

Section: Ir-measurement For Real-time Quantification Of Ch 4 and Comentioning

confidence: 99%

Characterization of metal oxide gas sensors via optical techniques

et al. 2020

View full text Add to dashboard Cite

Metal oxide (MOX) sensors are increasingly gaining attention in analytical applications. Their fundamental operation principle is based on conversion reactions of selected molecular species at their semiconducting surface. However, the exact turnover of analyte gas in relation to the concentration has not been investigated in detail to date. In the present study, two optical sensing techniques—luminescence quenching for molecular oxygen and infrared spectroscopy for carbon dioxide and methane—have been coupled for characterizing the behavior of an example semiconducting MOX methane gas sensor integrated into a recently developed low-volume gas cell. Thereby, oxygen consumption during MOX operation as well as the generation of carbon dioxide from the methane conversion reaction could be quantitatively monitored. The latter was analyzed via a direct mid-infrared gas sensor system based on substrate-integrated hollow waveguide (iHWG) technology combined with a portable Fourier transform infrared spectrometer, which has been able to not only detect the amount of generated carbon dioxide but also the consumption of methane during MOX operation. Hence, a method based entirely on direct optical detection schemes was developed for characterizing the actual signal generating processes—here for the detection of methane—via MOX sensing devices via near real-time online analysis.

show abstract

SnO2: The most important base material for semiconducting metal oxide-based materials

Cited by 10 publications

References 87 publications

Role of Heterojunctions of Core–Shell Heterostructures in Gas Sensing

Role of Heterojunctions of Core–Shell Heterostructures in Gas Sensing

On the Role of Heterojunctions of Core-Shell Heterostructures in Gas Sensing

Characterization of metal oxide gas sensors via optical techniques

Contact Info

Product

Resources

About