Surface conduction mechanisms and the electrical properties of Al2O3 humidity sensor

Khanna, Vinod Kumar; Nahar, R.K.

doi:10.1016/0169-4332(87)90126-7

Cited by 67 publications

(41 citation statements)

References 21 publications

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“…[3] In particular HfO 2 , due to the high quality dielectric properties of its polycrystalline films, its high permittivity and stability in contact with silicon, its high density, high heat of formation, and relatively large band gap, has been extensively studied as a replacement for SiO 2 as the gate-oxide insulating material for sub-0.1 lm complementary metal oxide semiconductor (CMOS) devices. [4] These materials are also of interest as insulating dielectrics in the capacitive elements in many memory devices such as DRAM, and in thin-film electroluminescent (TFEL) applications.…”

Section: Introductionmentioning

confidence: 99%

Growth of Hafnium Dioxide Thin Films by MOCVD Using a New Series of Cyclopentadienyl Hafnium Compounds

Carta¹,

Habra²,

Rossetto³

et al. 2007

Chemical Vapor Deposition

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Thin films of HfO 2 are grown by metal-organic (MO)CVD on Si(001) and fused quartz substrates in the temperature range 400-500°C, using a new series of bis-cyclopentadienyl bis-amino-alkoxide hafnium precursors, namely [(C 5 H 5 ) 2 Hf{OC(CH 3 ) 2 CH 2 N(CH 3 ) 2 } 2 ] and [(C 5 H 5 ) 2 Hf{OCH(CH 3 )CH 2 N(CH 3 ) 2 } 2 ], stable in air because of their strong coordination to the metal center. The films obtained are investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Rutherford backscattering spectroscopy (RBS), and atomic force microscopy (AFM). Monoclinic phase HfO 2 (baddeleyite) films, characterized by a correct stoichiometric ratio and a granular surface morphology with a roughness/thickness ratio that decreases with increasing deposition rate, are obtained.

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Section: Introductionmentioning

confidence: 99%

Growth of Hafnium Dioxide Thin Films by MOCVD Using a New Series of Cyclopentadienyl Hafnium Compounds

Carta¹,

Habra²,

Rossetto³

et al. 2007

Chemical Vapor Deposition

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“…Thin films of zirconium dioxide (ZrO 2 ) and hafnium dioxide (HfO 2 ) have a variety of important technological applications, such as protective coatings, [1] mirrors, [2] sensors, [3] and dielectric films in microelectronics. [4] In particular, ZrO 2 and HfO 2 have high permittivities and are stable in contact with silicon, making them promising candidates to replace SiO 2 as the gate dielectric material for sub-0.1 lm complementary metal±oxide-semiconductor (CMOS) technology.…”

Section: Introductionmentioning

confidence: 99%

Novel Mononuclear Alkoxide Precursors for the MOCVD of ZrO2 and HfO2 Thin Films

Williams

Roberts

Jones³

et al. 2002

Chem. Vap. Deposition

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Thin films of ZrO 2 and HfO 2 have been deposited by liquid injection metal±organic (MO)CVD using a range of new alkoxide precursors, [Zr(O t Bu) 2 (mmp) 2 ] (1), [Hf(O t Bu) 2 (mmp) 2 ] (2), [Zr(mmp) 4 ] (3), and [Hf(mmp) 4 ] (4): (mmp = 1-methoxy-2-methyl-2-propanolate, OCMe 2 CH 2 OMe). The complexes are mononuclear and volatile, and are significantly less reactive to air and moisture than existing Zr and Hf alkoxide precursors such as [Zr(O t Bu) 4 ] and [Hf(O t Bu) 4 ]. The ZrO 2 and HfO 2 films were grown over a wide range of substrate temperatures (350±650 C), and analysis by laser Raman spectroscopy shows that the films were deposited in the thermodynamically stable a-or monoclinic phase.

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“…Humidity sensing characteristics of the devices based on asprepared AAOs and pore-widened ones exhibited only quasilinear response in semi-logarithmic scale of the capacitances, [22][23][24][25][26][27] which might hinder a humidity measurement with a high degree of accuracy. In this paper, we suggest a very simple and effective solution for increasing the humidity sensing capability, in which the barrier oxide layer plays an important role.…”

Section: 28mentioning

confidence: 99%

“…Sensor-A showed quite linear responsive variations of capacitance in the intermediate RH regions (40-70% under 100 kHz and 60-90% under 1 MHz), whereas the capacitance were varied only in the high RH region ($75%) in Sensor-B, which was comparable to the previous reports at relatively high frequencies. [22][23][24][25][26][27] The barrier oxide layer in Sensor-A might play an important role for storing the humidity inside the nanopores more effectively resulting in the linear variation of the capacitance even in the relatively low RH region without applying sophisticated add-ons, 70 for examples magnetic eld 28 or water-sensitive sol-gel materials (e.g., polyethylene glycol).…”

Section: P-conjugated Polymer Nanowires With Various Diametersmentioning

confidence: 99%

“…[1][2][3][4] Aer the report on the two-step anodization resulting in a distinct improvement of the structural periodicities over the extended spatial regime, 5,6 anodic aluminum oxides (AAOs) have been widely adopted in diverse research elds, such as representative nanoporous templates for one-dimensional (1-dim.) nanostructures, [7][8][9][10][11][12][13] membrane lters, [14][15][16][17] evaporation/etching masks, 18-21 humidity sensors, [22][23][24][25][26][27][28] energy storage devices, [29][30][31][32] and bio-applications, [33][34][35][36] etc. These applications excluding surface treatments require AAOs with freestanding forms, i.e., separation from aluminum (Al) substrate, thus various strategies have been developed in the viewpoints of not only AAO fabricating (anodizing) but also AAO separating procedure.…”

Section: Introductionmentioning

confidence: 99%

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Massive, eco-friendly, and facile fabrication of multi-functional anodic aluminum oxides: application to nanoporous templates and sensing platforms

Jeong

Hong

et al. 2017

RSC Adv.

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In this paper, we report on an efficient and eco-friendly approach to fabricate AAOs in oxalic acid electrolyte, which exhibits a relatively wide range of electrolyte temperatures for stable anodization. Our strategy consists of simultaneous multi-surfaces anodization (SMSA) for fabricating plural AAOs and direct detachment of those AAOs from an aluminum (Al) substrate by applying stair-like reverse biases (SRBs) in the same electrolyte used for the SMSAs. A unit sequence including SMSA sequentially combined with SRBs-based detachment can be applied repeatedly to the same Al substrate for mass production of AAOs. Dimensional characteristics of AAOs were quantitatively controlled with respect to the electrolyte temperature as well as the number of applied sequences, and SRBs-based direct detaching characteristics depending on the AAO thickness were investigated as a function of the number of stairs in SRBs. The AAOs fabricated here were used as nanoporous templates for synthesizing pconjugated polymer nanomaterials with various diameters, and their structural and optical characteristics were studied with respect to their physical dimensions. We also fabricated capacitive humidity sensors designed on interdigitated electrode structures with nanoporous AAOs, and discussed their superior device performances.

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Surface conduction mechanisms and the electrical properties of Al2O3 humidity sensor

Cited by 67 publications

References 21 publications

Growth of Hafnium Dioxide Thin Films by MOCVD Using a New Series of Cyclopentadienyl Hafnium Compounds

Growth of Hafnium Dioxide Thin Films by MOCVD Using a New Series of Cyclopentadienyl Hafnium Compounds

Novel Mononuclear Alkoxide Precursors for the MOCVD of ZrO2 and HfO2 Thin Films

Massive, eco-friendly, and facile fabrication of multi-functional anodic aluminum oxides: application to nanoporous templates and sensing platforms

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