Two dimensional electron gases in polycrystalline MgZnO/ZnO heterostructures grown by rf-sputtering process

Chin, Huai-An; Cheng, I-Chun; Huang, Chih-I; Wu, Yuh‐Renn; Lu, Wen-Sen; Lee, Wei‐Li; Chen, Jian-Zhang; Chiu, Kuo-Chuang; Lin, Tzu‐Yu

doi:10.1063/1.3475500

Cited by 77 publications

(51 citation statements)

References 31 publications

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“…The physical distance between this plane of a high carrier density and the gate dielectric surface is expected to suppress both long‐range Coulomb scattering by trapped charges and short‐range scattering from dielectric surface topological imperfections and chemical defects. The term 2DEG is used here since charge conduction in these homojunctions is still ideal as seen in phonon‐limited ZnMgO/ZnO heterojunctions grown by molecular beam epitaxy (MBE) and in the temperature‐independent regime as seen in sputtered ZnMgO/ZnO heterojunctions . Further optimization of film solution‐processing and dopant chemistry would likely improve the performance further.…”

Section: Performance Metrics Of the Indicated Tft Devices On Si/sio2 mentioning

confidence: 99%

Polymer Doping Enables a Two‐Dimensional Electron Gas for High‐Performance Homojunction Oxide Thin‐Film Transistors

et al. 2018

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deposition (PLD), and radiofrequency sputtering. [2,[11][12][13] Nevertheless, solutionprocessing of MO precursors holds significant promise for lower cost production and compatibility with flexible substrates. [2,9,14,15] In this regard, indium oxide (In 2 O 3 ) is one of the most investigated solution-processed oxide semiconductors, [7,[16][17][18][19][20][21] however, the carrier density of pristine In 2 O 3 is difficult to control and In 2 O 3 films are usually polycrystalline, limiting their performance uniformity over large areas as well as mechanical flexibility. [22] To address both of these issues, metals such as Zn and/or Ga are added to In 2 O 3 , enabling the growth of amorphous MO thin films with enhanced electronic properties and ultimately affording far more stable TFT characteristics. [22][23][24][25][26] Recently, we reported a new strategy for high performance, near-zero threshold voltage (V Th ), bias stress-stable, and amorphous In 2 O 3 films and TFTs by simply doping the In 2 O 3 with an electrically insulating polymer such as poly(4-vinylphenol) (PVP) or polyethylenimine (PEI) to afford amorphous MO:polymer blend semiconducting nanocomposites. [2,17,22] The attraction of electron-rich PEI versus PVP is that the TFT High-performance solution-processed metal oxide (MO) thin-film transistors (TFTs) are realized by fabricating a homojunction of indium oxide (In 2 O 3 ) and polyethylenimine (PEI)-doped In 2 O 3 (In 2 O 3 :x% PEI, x = 0.5-4.0 wt%) as the channel layer. A two-dimensional electron gas (2DEG) is thereby achieved by creating a band offset between the In 2 O 3 and PEI-In 2 O 3 via work function tuning of the In 2 O 3 :x% PEI, from 4.00 to 3.62 eV as the PEI content is increased from 0.0 (pristine In 2 O 3 ) to 4.0 wt%, respectively. The resulting devices achieve electron mobilities greater than 10 cm 2 V −1 s −1 on a 300 nm SiO 2 gate dielectric. Importantly, these metrics exceed those of the devices composed of the pristine In 2 O 3 materials, which achieve a maximum mobility of ≈4 cm 2 V −1 s −1 . Furthermore, a mobility as high as 30 cm 2 V −1 s −1 is achieved on a high-k ZrO 2 dielectric in the homojunction devices. This is the first demonstration of 2DEG-based homojunction oxide TFTs via band offset achieved by simple polymer doping of the same MO material. Thin-Film TransistorsThe ORCID identification number(s) for the author(s) of this article can be found under https://doi.As a consequence of their outstanding charge transport properties and excellent optical transparency, metal oxide thin-film transistors (MOTFTs) have been heavily investigated for applications in state-of-the-art flat panel display technologies and next-generation electronics. [1][2][3][4][5][6][7][8][9][10] To date, several growth techniques have been utilized to fabricate MO films for TFTs including atomic layer deposition (ALD), pulsed-laser

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Section: Performance Metrics Of the Indicated Tft Devices On Si/sio2 mentioning

confidence: 99%

Polymer Doping Enables a Two‐Dimensional Electron Gas for High‐Performance Homojunction Oxide Thin‐Film Transistors

et al. 2018

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“…For optimal interface quality, epitaxial material growth is commonly carried out via MBE or pulsed laser deposition on single-crystal substrates, such as sapphire or ScAlMgO 4 ( 33 , 37 ). However, it was shown that 2DEG could also form in ZnO/ZnMgO heterointerfaces grown on glass substrates via less elaborate techniques, such as RF sputtering ( 36 ). Despite their polycrystalline nature, the heterointerfaces exhibited enhanced sheet electron concentration and mobility with a characteristic temperature-independent behavior ( 36 ).…”

Section: Introductionmentioning

confidence: 99%

“…However, it was shown that 2DEG could also form in ZnO/ZnMgO heterointerfaces grown on glass substrates via less elaborate techniques, such as RF sputtering ( 36 ). Despite their polycrystalline nature, the heterointerfaces exhibited enhanced sheet electron concentration and mobility with a characteristic temperature-independent behavior ( 36 ). …”

Section: Introductionmentioning

confidence: 99%

Heterojunction oxide thin-film transistors with unprecedented electron mobility grown from solution

et al. 2017

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“…A 2DEG formed at the interface has also been reported using ZnO/ZnMgO (Ref. 41) interfaces and bilayered In 2 O 3 -ZnO TFTs processed form solution can now achieve over 45 cm 2 V À1 s À1 mobility. 42 These trap sites often cause shifts in threshold voltage and affect leakage characteristics.…”

Section: Introductionmentioning

confidence: 66%

Solution processed ZnO homogeneous quasisuperlattice materials

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et al. 2017

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Heterogeneous multilayered oxide channel materials have enabled low temperature, high mobility thin film transistor technology by solution processing. The authors report the growth and characterization of solution-based, highly uniform and c-axis orientated zinc oxide (ZnO) single and multilayered thin films. Quasisuperlattice (QSL) metal oxide thin films are deposited by spin-coating and the structural, morphological, optical, electronic, and crystallographic properties are investigated. In this work, the authors show that uniform, coherent multilayers of ZnO can be produced from liquid precursors using an iterative coating-drying technique that shows epitaxial-like growth on SiO2, at a maximum temperature of 300 °C in air. As QSL films are grown with a greater number of constituent layers, the crystal growth direction changes from m-plane to c-plane, confirmed by x-ray and electron diffraction. The film surface is smooth for all QSLs with root mean square roughness <0.14 nm. X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) of electronic defects in the QSL structure show a dependence of defect emission on the QSL thickness, and PL mapping demonstrates that the defect signature is consistent across the QSL film in each case. XPS and valence-band analysis shown a remarkably consistent surface composition and electronic structure during the annealing process developed here.

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Two dimensional electron gases in polycrystalline MgZnO/ZnO heterostructures grown by rf-sputtering process

Cited by 77 publications

References 31 publications

Polymer Doping Enables a Two‐Dimensional Electron Gas for High‐Performance Homojunction Oxide Thin‐Film Transistors

Polymer Doping Enables a Two‐Dimensional Electron Gas for High‐Performance Homojunction Oxide Thin‐Film Transistors

Heterojunction oxide thin-film transistors with unprecedented electron mobility grown from solution

Solution processed ZnO homogeneous quasisuperlattice materials

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