Alwin Daus is a postdoctoral scholar in the Department of Electrical Engineering (Prof. Eric Pop's group) since November 2018. He is supported by the Postdoc.Mobility Fellowship from the Swiss National Science Foundation. He obtained his PhD degree from ETH Zurich (Switzerland), where he worked on flexible electronics. He did his B.Sc. and M.Sc. in Electrical Engineering at Technische Universitaet Braunschweig (Germany). During his B.Sc. and M.Sc studies, he did research stays and internships at Princeton University (Surface Chemistry), Robert Bosch LLC (MEMS), and Philips Technologie GmbH (OLED Lighting).
Doctor of Science, Eidgenossische Technische Hochschule (ETH Zurich) (2018)
Master of Science, Technische Universitat Braunschweig, Electrical Engineering (2013)
Bachelor of Science, Technische Universitat Braunschweig (2010)
Current Research and Scholarly Interests
- Transistors based on 2D materials and their implementation on flexible substrates.
- New device architectures for steep-slope switching and low-voltage operation.
- Long-Term Aging of Al2O3 Passivated and Unpassivated Flexible a-IGZO TFTs IEEE TRANSACTIONS ON ELECTRON DEVICES 2020; 67 (11): 4934–39
Flexible Low-Power Superlattice-Like Phase Change Memory
View details for Web of Science ID 000615719100024
- Flexible Green Perovskite Light Emitting Diodes IEEE JOURNAL OF THE ELECTRON DEVICES SOCIETY 2019; 7 (1): 769–75
- Improvement of contact resistance in flexible a-IGZO thin-film transistors by CF4/O-2 plasma treatment SOLID-STATE ELECTRONICS 2018; 150: 23–27
- N-type to p-type transition upon phase change in Ge6Sb1Te2 compounds APPLIED PHYSICS LETTERS 2018; 113 (10)
- Design of Engineered Elastomeric Substrate for Stretchable Active Devices and Sensors ADVANCED FUNCTIONAL MATERIALS 2018; 28 (30)
Metal-Halide Perovskites for Gate Dielectrics in Field-Effect Transistors and Photodetectors Enabled by PMMA Lift-Off Process
2018; 30 (23): e1707412
Metal-halide perovskites have emerged as promising materials for optoelectronics applications, such as photovoltaics, light-emitting diodes, and photodetectors due to their excellent photoconversion efficiencies. However, their instability in aqueous solutions and most organic solvents has complicated their micropatterning procedures, which are needed for dense device integration, for example, in displays or cameras. In this work, a lift-off process based on poly(methyl methacrylate) and deep ultraviolet lithography on flexible plastic foils is presented. This technique comprises simultaneous patterning of the metal-halide perovskite with a top electrode, which results in microscale vertical device architectures with high spatial resolution and alignment properties. Hence, thin-film transistors (TFTs) with methyl-ammonium lead iodide (MAPbI3 ) gate dielectrics are demonstrated for the first time. The giant dielectric constant of MAPbI3 (>1000) leads to excellent low-voltage TFT switching capabilities with subthreshold swings ≈80 mV decade-1 over ≈5 orders of drain current magnitude. Furthermore, vertically stacked low-power Au-MAPbI3 -Au photodetectors with close-to-ideal linear response (R2 = 0.9997) are created. The mechanical stability down to a tensile radius of 6 mm is demonstrated for the TFTs and photodetectors, simultaneously realized on the same flexible plastic substrate. These results open the way for flexible low-power integrated (opto-)electronic systems based on metal-halide perovskites.
View details for DOI 10.1002/adma.201707412
View details for Web of Science ID 000434036000014
View details for PubMedID 29696710
Photo-Induced Room-Temperature Gas Sensing with a-IGZO Based Thin-Film Transistors Fabricated on Flexible Plastic Foil
2018; 18 (2)
We present a gas sensitive thin-film transistor (TFT) based on an amorphous Indium-Gallium-Zinc-Oxide (a-IGZO) semiconductor as the sensing layer, which is fabricated on a free-standing flexible polyimide foil. The photo-induced sensor response to NO₂ gas at room temperature and the cross-sensitivity to humidity are investigated. We combine the advantages of a transistor based sensor with flexible electronics technology to demonstrate the first flexible a-IGZO based gas sensitive TFT. Since flexible plastic substrates prohibit the use of high operating temperatures, the charge generation is promoted with the help of UV-light absorption, which ultimately triggers the reversible chemical reaction with the trace gas. Furthermore, the device fabrication process flow can be directly implemented in standard TFT technology, allowing for the parallel integration of the sensor and analog or logical circuits.
View details for DOI 10.3390/s18020358
View details for Web of Science ID 000427544000041
View details for PubMedID 29373524
View details for PubMedCentralID PMC5855925
Flexible CMOS electronics based on p-type Ge2Sb2Te5 and n-type InGaZnO4 semiconductors
IEEE International Electron Devices Meeting (IEDM)
View details for DOI 10.1109/IEDM.2017.8268349
Ge₂Sb₂Te₅ p-Type Thin-Film Transistors on Flexible Plastic Foil.
Materials (Basel, Switzerland)
2018; 11 (9)
In this work, we show the performance improvement of p-type thin-film transistors (TFTs) with Ge 2 Sb 2 Te 5 (GST) semiconductor layers on flexible polyimide substrates, achieved by downscaling of the GST thickness. Prior works on GST TFTs have typically shown poor current modulation capabilities with ON/OFF ratios ≤20 and non-saturating output characteristics. By reducing the GST thickness to 5 nm, we achieve ON/OFF ratios up to ≈300 and a channel pinch-off leading to drain current saturation. We compare the GST TFTs in their amorphous (as deposited) state and in their crystalline (annealed at 200 ∘ C) state. The highest effective field-effect mobility of 6.7 cm 2 /Vs is achieved for 10-nm-thick crystalline GST TFTs, which have an ON/OFF ratio of ≈16. The highest effective field-effect mobility in amorphous GST TFTs is 0.04 cm 2 /Vs, which is obtained in devices with a GST thickness of 5 nm. The devices remain fully operational upon bending to a radius of 6 mm. Furthermore, we find that the TFTs with amorphous channels are more sensitive to bias stress than the ones with crystallized channels. These results show that GST semiconductors are compatible with flexible electronics technology, where high-performance p-type TFTs are strongly needed for the realization of hybrid complementary metal-oxide-semiconductor (CMOS) technology in conjunction with popular n-type oxide semiconductor materials.
View details for DOI 10.3390/ma11091672
View details for PubMedID 30205624
View details for PubMedCentralID PMC6165447
- Ferroelectric-Like Charge Trapping Thin-Film Transistors and Their Evaluation as Memories and Synaptic Devices ADVANCED ELECTRONIC MATERIALS 2017; 3 (12)
- Gain-Tunable Complementary Common-Source Amplifier Based on a Flexible Hybrid Thin-Film Transistor Technology IEEE ELECTRON DEVICE LETTERS 2017; 38 (11): 1536–39
- Biodegradable and Highly Deformable Temperature Sensors for the Internet of Things ADVANCED FUNCTIONAL MATERIALS 2017; 27 (35)
Buckled Thin-Film Transistors and Circuits on Soft Elastomers for Stretchable Electronics
ACS APPLIED MATERIALS & INTERFACES
2017; 9 (34): 28750–57
Although recent progress in the field of flexible electronics has allowed the realization of biocompatible and conformable electronics, systematic approaches which combine high bendability (<3 mm bending radius), high stretchability (>3-4%), and low complexity in the fabrication process are still missing. Here, we show a technique to induce randomly oriented and customized wrinkles on the surface of a biocompatible elastomeric substrate, where Thin-Film Transistors (TFTs) and circuits (inverter and logic NAND gates) based on amorphous-IGZO are fabricated. By tuning the wavelength and the amplitude of the wrinkles, the devices are fully operational while bent to 13 μm bending radii as well as while stretched up to 5%, keeping unchanged electrical properties. Moreover, a flexible rectifier is also realized, showing no degradation in the performances while flat or wrapped on an artificial human wrist. As proof of concept, transparent TFTs are also fabricated, presenting comparable electrical performances to the nontransparent ones. The extension of the buckling approach from our TFTs to circuits demonstrates the scalability of the process, prospecting applications in wireless stretchable electronics to be worn or implanted.
View details for DOI 10.1021/acsami.7b08153
View details for Web of Science ID 000409395500068
View details for PubMedID 28795567
- Measurement of Young's modulus and residual stress of atomic layer deposited Al2O3 and Pt thin films JOURNAL OF MICROMECHANICS AND MICROENGINEERING 2017; 27 (8)
- Oxide Thin-Film Electronics on Carbon Fiber Reinforced Polymer Composite IEEE ELECTRON DEVICE LETTERS 2017; 38 (8): 1043–46
- Geometry-Based Tunability Enhancement of Flexible Thin-Film Varactors IEEE ELECTRON DEVICE LETTERS 2017; 38 (8): 1117–20
- Charge Trapping Mechanism Leading to Sub-60-mV/decade-Swing FETs IEEE TRANSACTIONS ON ELECTRON DEVICES 2017; 64 (7): 2789–96
- Positive charge trapping phenomenon in n-channel thin-film transistors with amorphous alumina gate insulators JOURNAL OF APPLIED PHYSICS 2016; 120 (24)
- Flexible a-IGZO Phototransistor for Instantaneous and Cumulative UV-Exposure Monitoring for Skin Health ADVANCED ELECTRONIC MATERIALS 2016; 2 (10)
- Flexible In-Ga-Zn-O Thin-Film Transistors on Elastomeric Substrate Bent to 2.3% Strain IEEE ELECTRON DEVICE LETTERS 2015; 36 (8): 781–83
- Development of silicon microforce sensors integrated with double meander springs for standard hardness test instruments SPIE-INT SOC OPTICAL ENGINEERING. 2015
Design and simulation of a 800 Mbit/s data link for magnetic resonance imaging wearables
IEEE. 2015: 1323–26
This paper presents the optimization of electronic circuitry for operation in the harsh electro magnetic (EM) environment during a magnetic resonance imaging (MRI) scan. As demonstrator, a device small enough to be worn during the scan is optimized. Based on finite element method (FEM) simulations, the induced current densities due to magnetic field changes of 200 T s(-1) were reduced from 1 × 10(10) A m(-2) by one order of magnitude, predicting error-free operation of the 1.8V logic employed. The simulations were validated using a bit error rate test, which showed no bit errors during a MRI scan sequence. Therefore, neither the logic, nor the utilized 800 Mbit s(-1) low voltage differential swing (LVDS) data link of the optimized wearable device were significantly influenced by the EM interference. Next, the influence of ferro-magnetic components on the static magnetic field and consequently the image quality was simulated showing a MRI image loss with approximately 2 cm radius around a commercial integrated circuit of 1×1 cm(2). This was successively validated by a conventional MRI scan.
View details for Web of Science ID 000371717201152
View details for PubMedID 26736512