The impact of post-deposition annealing on the performance of solution-processed single layer In2O3 and isotype In2O3/ZnO heterojunction transistors

Tetzner, Kornelius; Isakov, Ivan; Regoutz, Anna; Payne, David J.; Anthopoulos, Thomas D.

doi:10.1039/c6tc04907a

Cited by 34 publications

(45 citation statements)

References 33 publications

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“…A notably successful strategy to enhance TFT performance, including MO‐ and organic‐based TFTs, utilizes semiconducting channel heterojunctions . Here, the Fermi energy alignment between two semiconductors in contact leads to band bending at the semiconductor heterojunction, thereby forming a two‐dimensional electron gas (2DEG) at this interface . To date, 2DEG MO transistors have been fabricated using pristine/metal‐doped In 2 O 3 and ZnO heterojunctions, with ZnO/ZnMgO and In 2 O 3 /ZnO being the most investigated .…”

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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“…It is important to note that the use of a heterostructure semiconductor channel has been demonstrated to increase the electron mobility in metal‐oxide transistors (e.g., ZnO/In 2 O 3 and InZnO/AlSnZnInO ) in addition to controlled modulation doping of ZnO/In 2 O 3 . These techniques have resulted in unprecedented improvements to charge transport .…”

Section: Introductionmentioning

confidence: 99%

Use of high-k encapsulation to improve mobility in trap-limited metal-oxide semiconductors

Zeumault

Subramanian

2017

Phys. Status Solidi B

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Low‐temperature spray‐deposited ZnO films are encapsulated by insulating Ga2O3 films and the resulting electronic properties of heterostructure films and transistors are analyzed and compared to un‐encapsulated ZnO as a function of processing temperature. An enhancement in Hall mobility and field‐effect mobility is observed similar to when high‐k dielectrics are used as gate‐dielectrics in transparent conductive oxide thin‐film transistors except without the presence of undesirable device behavior such as gate‐leakage and hysteresis. Based on a recently proposed theory consisting of electron donation from high‐k dielectrics, work function measurements show that conditions for electron transfer from Ga2O3 to ZnO can be met by optimally‐tuning the deposition temperature of the respective films resulting in an effective doping which is qualitatively similar to modulation doping. As a result, TFTs composed of ZnO/Ga2O3 heterostructures exhibit greatly improved switching characteristics and electron transport relative to the otherwise poor performance of low‐temperature processed ZnO achieved through a simple modification to TFT device structure.

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“…In this contribution, we expand on the concept of improving the performance of ZnO based polymer BHJ as well as colloidal quantum dot (CQD) solar cells by introducing an additional, extremely thin, indium oxide (In 2 O 3 ) layer in between the cathode (ITO) and the ZnO film. The resulting bilayer architecture has recently been shown to lead to dramatic improvements in the electron mobility of TFTs, achieving field‐effect mobilities of up to 45 cm 2 /Vs due to synergistic effects of an extremely chemically sharp In 2 O 3 /ZnO interface and the presence of a two‐dimensionally (2D) confined electron cloud at the interface . The use of such a bilayer structure has also briefly been previously reported in our group in organic BHJ solar cells with copper iodide (CuI) as the hole transporting layer (HTL), as well as more recently in high efficiency BHJ OPVs, but has not been studied in detail.…”

Section: Introductionmentioning

confidence: 89%

“…As anticipated, the electron saturation mobility ( μ sat ) of ZnO(aq) is close to 1 cm 2 /Vs, roughly two orders of magnitude higher than the mobility of ZnO(s‐g). Following the procedure developed in our laboratory, we then proceeded to fabricate In 2 O 3 /ZnO bilayer transistors. As expected, heterojunction channel TFTs with ZnO(aq) results in a substantial increase in the electron mobility to around 5 cm 2 V −1 s −1 and, interestingly, a more than 1000 time increase in the mobility of ZnO (s‐g) to a similar value (Table ).…”

Section: Electron Transport In Bilayer In2o3/zno Etlsmentioning

confidence: 99%

Solution‐Processed In₂O₃/ZnO Heterojunction Electron Transport Layers for Efficient Organic Bulk Heterojunction and Inorganic Colloidal Quantum‐Dot Solar Cells

et al. 2018

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We report the development of a solution‐processed In2O3/ZnO heterojunction electron transport layer (ETL) and its application in high efficiency organic bulk‐heterojunction (BHJ) and inorganic colloidal quantum dot (CQD) solar cells. Study of the electrical properties of this low‐dimensional oxide heterostructure via field‐effect measurements reveals that electron transport along the heterointerface is enhanced by more than a tenfold when compared to the individual single‐layer oxides. Use of the heterojunction as the ETL in organic BHJ photovoltaics is found to consistently improve the cell's performance due to the smoothening of the ZnO surface, increased electron mobility and a noticeable reduction in the cathode's work function, leading to a decrease in the cells’ series resistance and a higher fill factor (FF). Specifically, non‐fullerene based organic BHJ solar cells based on In2O3/ZnO ETLs exhibit very high power conversion efficiencies (PCE) of up to 12.8%, and high FFs of over 70%. The bilayer ETL concept is further extended to inorganic lead‐sulphide CQD solar cells. Resulting devices exhibit excellent performance with a maximum PCE of 8.2% and a FF of 56.8%. The present results highlight the potential of multilayer oxides as novel ETL systems and lay the foundation for future developments.

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The impact of post-deposition annealing on the performance of solution-processed single layer In₂O₃ and isotype In₂O₃/ZnO heterojunction transistors

Abstract: The influence of annealing temperature on electron transport in single layer In2O3 and isotype In2O3/ZnO heterojunction channel transistors is investigated.

Cited by 34 publications

References 33 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

Use of high-k encapsulation to improve mobility in trap-limited metal-oxide semiconductors

Solution‐Processed In₂O₃/ZnO Heterojunction Electron Transport Layers for Efficient Organic Bulk Heterojunction and Inorganic Colloidal Quantum‐Dot Solar Cells

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The impact of post-deposition annealing on the performance of solution-processed single layer In2O3 and isotype In2O3/ZnO heterojunction transistors

Abstract: The influence of annealing temperature on electron transport in single layer In2O3 and isotype In2O3/ZnO heterojunction channel transistors is investigated.

Cited by 34 publications

References 33 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

Use of high-k encapsulation to improve mobility in trap-limited metal-oxide semiconductors

Solution‐Processed In2O3/ZnO Heterojunction Electron Transport Layers for Efficient Organic Bulk Heterojunction and Inorganic Colloidal Quantum‐Dot Solar Cells

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Product

Resources

About

The impact of post-deposition annealing on the performance of solution-processed single layer In₂O₃ and isotype In₂O₃/ZnO heterojunction transistors

Solution‐Processed In₂O₃/ZnO Heterojunction Electron Transport Layers for Efficient Organic Bulk Heterojunction and Inorganic Colloidal Quantum‐Dot Solar Cells