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Printing Electronics using Inorganic Nanomaterials

Printed electronics is a rapidly developing field of research that involves solution processing and covers a broad range of research activities, starting from a basic field-effect transistor to complex logics, memories, lighting, photovoltaics and sensors.

Printed logics is the most complex and intriguing part of it. In order to fulfill the promise of large area devices on inexpensive substrates, such as paper, plastic etc., it is essential to limit the process temperature to lowest possible values. Consequently, organic materials have traditionally been used, although long-term stability and device mobility were always been the issues of concern. Inorganic materials, e.g., oxide semiconductors, on the other hand, show much superior electrical performance once they are processed at high temperatures. However, a reduction in the process temperature drastically reduces the device performance. Research focus now is to reduce the process temperature while keeping the device performance at the same level as high temperature processed electronics.

To carry this forward, in the printed electronics group at Institute of Nanotechnology we focus on the fundamental issues concerning solution-processed/ printed oxide electronics.

One key aspect of our research is that we concentrate on electrolyte-gating approach to ensure extremely high gating efficiency even with oxide semiconductors which when solution-processed usually result large interface/ surface roughness, thereby reducing the dielectric efficiency/ polarizability. However, our composite polymer electrolytes can easily follow any surface corrugation offered by the nanostructured oxide semiconductors towards a highly conformal semiconductor/ dielectric interface.

Equipments

HELMHOLTZ VIRTUAL INSTITUTE- 530: Printed electronics from oxide nanomaterials- from fabrication, characterization to reliability studies'

 

In the news!

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Room Temperature Processing of High Performance Oxide Electronics

Room teperature processed field-effect transistors are fabricated using a chemically controlled curing process of the printed nanoparticle ink that provides surprisingly dense thin films and excellent interparticle electrical contacts and a device mobility as large as 12.5 cm2/(V s)

ACS Nano, 2015, 9 (3), pp 3075–3083
AAM
Temperature-Dependent Performance of Electrolyte-gated Field-Effect Transistors

The temperature dependence of the Composite Solid Polymer Electrolyte (CSPE)-gated FETs is studied. This study offers an insight into the physical and electrical properties of the CSPEs.

ACS Appl. Mater. Interfaces, 2016, 8 (46), pp 31757–31763
 

Sub-50 nm Channel Vertical Field-Effect Transistors using Conventional Ink-Jet Printing

A printed vertical field-effect transistor is demonstrated, which decouples critical device dimensions from printing resolution. A printed mesoporous semiconductor layer, sandwiched between vertically stacked drive electrodes, provides <50 nm channel lengths. A polymer-electrolyte-based gate insulator infiltrates the percolating pores of the mesoporous channel to accumulate charge carriers at every semiconductor domain, thereby, resulting in an unprecedented current density of MA cm−2.

 

 

 

 

 

 

Figure 1 a) System comprising the bottom drive electrode along with the printed metal–organic precursor ink that would form the mesoporous semiconductor layer upon annealing. b) After structuring and placing the top drive electrode. c) After the annealing process that removes the polymer and opens the pores; the porous semiconductor channel layer is now sandwiched between the drive electrodes. d) The final vFET geometry after printing the polymer electrolyte (gate dielectric)that covers the porous channel and the displaced gate electrode. e) SEM image showing the actual porous SnO2 surface morphology; the bright white phase represents the material and the dark regions show the pores. f) 3D surface rendering of the reconstructed STEM tomography showing the 3D structure of SnO2. All the images were generated from the sample annealed at 550 °C for 5 min.

Learn more: Tessy. Baby et al., Advanced Materials, 29 (4), 2017, 1603858

Digital power and performance analysis of inkjet printed ring oscillators based on electrolyte-gated oxide electronics

A systematic methodology for characterizing ring oscillators in the printed electronics domain is explained. This greatly helps in predicting the switching capacitance and driver capability at each stage, as well as the power consumption of our ink-jet printed ring oscillators. We present inkjet printed circuits which are able to operate at supply voltages as low as ≤2 V. The ink-jet printed inverters show a gain of ∼4 and 2.3 ms propagation delay time at 1 V supply voltage. Subsequently built 3-stage ring oscillators start to oscillate at a supply voltage of only 0.6 V with a frequency of ∼255 Hz and can reach frequencies up to ∼350 Hz at 2 V supply voltage.

 

 

 

 

 

 

 

Figure 1 Layout of a three stage ring oscillator, fabricated by laser ablation of ITO glass

 

 

 Figure 2 (a) Output characteristics of a three-stage ring oscillator at a supply voltage VDD of 2 V. (b) Dependency of the frequency f from the supply voltage VDD.

 

Consequently, the output characteristics as well as the gain of our invertor at a supply voltage of 1V is measured. The maximum gain is 4.4 at an output voltage of 0.55V, which is close to VDD/2. The propoagation delay time was measured to be 2.3 ms. 

 

 

 

Learn more: Gabriel C M et al.Appl. Phys. Lett. 111, 102103 (2017); doi: http://dx.doi.org/10.1063/1.4991919

Hybrid supercapacitors for reversible control of magnetism

Electric field tuning of magnetism is one of the most intensely pursued research topics of recent times aiming at the development of new-generation low-power spintronics and microelectronics. However, a reversible magnetoelectric effect with an on/off ratio suitable for easy and precise device operation is yet to be achieved. Here we propose a novel route to robustly tune magnetism via the charging/discharging processes of hybrid supercapacitors, which involve electrostatic (electric-double-layer capacitance) and electrochemical (pseudocapacitance) doping. We use both charging mechanisms—occurring at the La0.74Sr0.26MnO3/ionic liquid interface to control the balance between ferromagnetic and non-ferromagnetic phases of La1 xSrxMnO3 to an unprecedented extent. A magnetic modulation of up to E33% is reached above room temperature when applying an external potential of only about 2.0 V. Our case study intends to draw attention to new, reversible physico-chemical phenomena in the rather unexplored area of magnetoelectric supercapacitors.

 

 

 

 

 

 

 

 

 

 

 

 

Figure  Sketch of the device and in situ measurement principle.

(a) Schematic of the electrochemical tuning cell: a La0.74Sr0.26MnO3 (LSMO) single-crystal thin film (≈13 nm) grown on a SrTiO3 substrate and a high-surface-area carbon cloth serve as working (WE) and counter (CE) electrodes, respectively. The electrodes are separated by an insulating glass fibre (not shown). On application of an external voltage, the ions of the ionic liquid (DEME+-TFSI) form physical or chemical bonds with the LSMO surface leading to electrostatic (electric-double-layer (EDL) capacitance) or electrochemical (pseudocapacitance (PS)) charge carrier doping, respectively. Both mechanisms allow for manipulating the magnetic state of LSMO. (b) Example of in situ tuning experiment performed at 323 K: the magnetic response (in red) reversibly follows the surface charge modulation (in blue), calculated by integrating the measured current density (in green), on repetitive cycling of the external potential (in black).

 

Learn more: Alan Molinari et al. Nat Commun. 2017; 8: 15339

Selected publications

1.  Cadilha Marques, G.; Garlapati, S. K.; Dehm, S.; Dasgupta, S.; Hahn, H.; Tahoori, M.; Aghassi-Hagmann, J., Applied physics letters, 111 (10), 102103, 2017, doi:10.1063/1.4991919
2.  Garlapati, S. K.; Gebauer, J. S.; Dehm, S.; Bruns, M.; Winterer, M.; Hahn, H.; Dasgupta, S., Advanced electronic materials, 3 (9), Art. Nr. 1600476, 2017, doi:10.1002/aelm.201600476
3.  Marques, G. C.; Garlapati, S. K.; Chatterjee, D.; Dehm, S.; Dasgupta, S.; Aghassi, J.; Tahoori, M. B., IEEE transactions on electron devices, 64 (1), 279–285, 2017, doi:10.1109/TED.2016.2621777
4.  Häming, M.; Baby, T. T.; Garlapati, S. K.; Krause, B.; Hahn, H.; Dasgupta, S.; Weinhardt, L.; Heske, C., Applied surface science, 396, 912–919, 2017, doi:10.1016/j.apsusc.2016.11.060
5.  Baby, T. T.; Rommel, M.; von Seggern, F.; Friederich, P.; Reitz, C.; Dehm, S.; Kübel, C.; Wenzel, W.; Hahn, H.; Dasgupta, S., Advanced materials, 29 (4), Art. Nr. 1603858, 2017, doi:10.1002/adma.201603858
6.  Stoesser, A.; Von Seggern, F.; Purohit, S.; Nasr, B.; Kruk, R.; Dehm, S.; Wang, D.; Hahn, H.; Dasgupta, S., Nanotechnology, 27 (41), Art.Nr.:415205, 2016, doi:10.1088/0957-4484/27/41/415205
7.  Dasgupta, S.; Das, B.; Li, Q.; Wang, D.; Baby, T. T.; Indris, S.; Knapp, M.; Ehrenberg, H.; Fink, K.; Kruk, R.; Hahn, H., Advanced functional materials, 26 (41), 7507-7515, 2016, doi:10.1002/adfm.201603411
8.  Sykora, B.; Wang, D.; Seggern, H. von., Applied physics letters, 109 (3), Art.Nr.:033501, 2016, doi:10.1063/1.4958701
9.  Breitung, B.; Baumann, P.; Sommer, H.; Janek, J.; Brezesinski, T., Nanoscale, 8 (29), 14048-14056, 2016, doi:10.1039/c6nr03575b
10. von Seggern, F.; Keskin, I.; Koos, E.; Kruk, R.; Hahn, H.; Dasgupta, S., ACS Applied Materials & Interfaces, 8 (46), 31757-31763, 2016, doi: 10.1021/acsami.6b10939