[paper] Organic semiconductor (OSC) OFETs

Boyu Peng, Ke Cao* Albert Ho Yuen Lau, Ming Chen, Yang Lu* and Paddy K. L. Chan

Crystallized Monolayer Semiconductor for Ohmic Contact Resistance, High Intrinsic Gain, and High Current Density

Adv. Mater. 2020, 32, 2002281 

DOI:10.1002/adma.202002281

Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road (HK)

*Department of Mechanical Engineering, City University of Hong Kong, Kowloon (HK)

Abstract: The contact resistance limits the downscaling and operating range of organic field-effect transistors (OFETs). Access resistance through multilayers of molecules and the nonideal metal/semiconductor interface are two major bottlenecks preventing the lowering of the contact resistance. In this work, monolayer (1L) organic crystals and nondestructive electrodes are utilized to overcome the abovementioned challenges. High intrinsic mobility of 12.5 cm2 V−1 s−1 and Ohmic contact resistance of 40 Ω cm are achieved. Unlike the thermionic emission in common Schottky contacts, the carriers are pre- dominantly injected by field emission. The 1L-OFETs can operate linearly from VDS = −1 V to VDS as small as −0.1 mV. Thanks to the good pinch-off behavior brought by the monolayer semiconductor, the 1L-OFETs show high intrinsic gain at the saturation regime. At a high bias load, a maximum current density of 4.2 µA µm−1 is achieved by the only molecular layer as the active channel, with a current saturation effect being observed. In addition to the low contact resistance and high-resolution lithography, it is suggested that the thermal management of high-mobility OFETs will be the next major challenge in achieving high-speed densely integrated flexible electronics.

Fig: a) Schematic charge accumulation and b) output curves of short-channel OFETs. c) Schematic charge accumulation and d) output curves of source-gated transistors. e) Schematic charge accumulation and f) output curves of 1L-OFETs. 

Acknowledgements: The authors gratefully acknowledge the support from the General Research Fund (GRF) under Grant Nos. HKU 17264016 and HKU 17204517, University of Hong Kong Seed Funding Grant Nos. 201711159068 and 201611159208. The authors appreciate Prof. Xin Cheng and Xin Zhuang from Southern University of Science and Technology for their support on e-beam lithography. The authors also thank Dr. Hagen Klauk and James W. Borchert for the fruitful discussions and suggestions.

[paper] Compact Modeling of Organic TFT

Jakob Pruefer, Jakob Leise, Ghader Darbandy, Aristeidis Nikolaou, Hagen Klauk, James W. Borchert, Benjamín Iñíguez, Fellow, IEEE, Thomas Gneiting, Member, IEEE

and Alexander Kloes, Senior Member, IEEE

Compact Modeling of Short-Channel Effects in Staggered Organic Thin-Film Transistors

IEEE Transactions on Electron Devices, vol. 67, no. 11, pp. 5082-5090, Nov. 2020

DOI: 10.1109/TED.2020.3021368.

Abstract:This article introduces analytical compact models of short-channel effects in staggered organic thinfilm transistors (TFTs). The effects of subthreshold-swing degradation, threshold-voltage roll-off, and drain-induced barrier lowering (DIBL) on the static current–voltage characteristics of staggered TFTs are extracted from an analytical potential solution of the 2-D problem of the staggered geometry. This solution is derived by using the Schwarz–Christoffel transformation that leads to a complex mapping function linking the staggered geometry to an equivalent in another coordinate system for which an analytical potential solution exists. The commercial TCAD is used to verify the compact models. Finally, the closed-form and physics-based equations are incorporated into an existing compact current model and verified by measurements on staggered organic TFTs with channel lengths as small as 0.4 µm fabricated on flexible plastic substrates by stencil lithography.

Fig:(a) Schematic cross section and (b) simplified geometry 

of the staggered organic TFTs for the TCAD simulations.

Acknowledgement: This work was supported in part by the German Federal Ministry of Education and Research under Grant 13FH015IX6 Strukturnahe Modellierung organischer flexibler KurzkanalTFTs (Structure-Oriented Modeling of Organic FLEXible short-channel TFTs) (SOMOFLEX), in part by the EU H2020 Marie Sklodowska-Curie actions (MSCA) Research and Innovation Staff Exchange (RISE) Project Design Oriented ModellINg for flexible electrOnics (DOMINO) under Grant 645760, and in part by the German Research Foundation (DFG) under Grant KL 1042/9-2 (SPP FFlexCom). 

[paper] Capacitive Sensor for Dental Implants

Alireza Hassanzadeh, Ali Moulavi and Amir Panahi

A New Capacitive Sensor for Histomorphometry Evaluation of Dental Implants

in IEEE Sensors Journal, 

DOI: 10.1109/JSEN.2020.3026745

Abstract: Knowing information about the internal functions of the human body has always been the subject of scientific research. Processing of the data from inside of the body gives access to valuable information for the therapist. In this paper, an implantable capacitive sensor has been designed and implemented inside the bone to evaluate the new bone growth. Reducing the medical x-ray imaging dose during a jaw scan is a motivation for the design of the sensor. The new capacitive sensor can replace multiple x-ray imaging sessions. Low energy consumption, stable performance, and information processing rate are some of the engineering challenges for implanted sensors. The designed sensor is a zero power module, which can easily be implemented in dental tooth implants without any active component. The capacitive sensor information can be transmitted to a reader device via a wireless inductive link. The sensor simulation results from a commercial software confirm experimental measurements. The fabricated sensor has been tested on the femur (thigh) bone and mandible bone (lower jaw). The sensor capacitance changes from 20nF to 1.57μF for the fabricated sensor and amount of the surrounding bone. Fabrication results show that variation of sensor capacitance from the early stage of the dental implant to full recovery and bone development is more than seven times. The wide range of sensor capacitance variation allows for better bone development characterization. 

Fig: a) Schematic of a typical sensor and reader inductive link, b) Reader and the implanted sensor.

[report] OptiBP smartphone app

Patrick Schoettker¹, Jean Degott¹, Gregory Hofmann¹, Martin Proença², Guillaume Bonnier², Alia Lemkaddem², Mathieu Lemay², Raoul Schorer³, Urvan Christen⁴, Jean‑François Knebel⁴, Arlene Wuerzner⁵, Michel Burnier⁵ and Gregoire Wuerzner⁵ 

Blood pressure measurements with the OptiBP smartphone app validated against reference auscultatory measurements

Scientific Reports Vol. 10, Article number: 17827 (2020)

DOI: 10.1038/s41598-020-74955-4 

  

¹Department of Anesthesiology, Lausanne University Hospital and University of Lausanne (CH)

²CSEM, Swiss Center for Electronics and Microtechnology, Neuchâtel (CH)

³Department of Acute Medicine, Geneva University Hospital and University of Geneva, (CH)

⁴Biospectal SA, 1003 Lausanne (CH)

⁵Service of Nephrology and Hypertension, Lausanne University Hospital and University of Lausanne,  (CH)

Abstract: Mobile health diagnostics have been shown to be efective and scalable for chronic disease detection and management. By maximizing the smartphones’ optics and computational power, they could allow assessment of physiological information from the morphology of pulse waves and thus estimate cufess blood pressure (BP). We trained the parameters of an existing pulse wave analysis algorithm (oBPM), previously validated in anaesthesia on pulse oximeter signals, by collecting optical signals from 51 patients fngertips via a smartphone while simultaneously acquiring BP measurements through an arterial catheter. We then compared smartphone-based measurements obtained on 50 participants in an ambulatory setting via the OptiBP app against simultaneously acquired auscultatory systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean blood pressure (MBP) measurements. Patients were normotensive (70.0% for SBP versus 61.4% for DBP), hypertensive (17.1% vs. 13.6%) or hypotensive (12.9% vs. 25.0%). The diference in BP (mean± standard deviation) between both methods were within the ISO 81,060–2:2018 standard for SBP (− 0.7 ± 7.7 mmHg), DBP (− 0.4 ± 4.5 mmHg) and MBP (− 0.6 ± 5.2 mmHg). These results demonstrate that BP can be measured with accuracy at the fnger using the OptiBP smartphone app. This may become an important tool to detect hypertension in various settings, for example in low-income countries, where the availability of smartphones is high but access to health care is low. 

Fig: OptiBP application utilizes image data generated from volumetric blood fow changes via light passing through the fngertip, refecting of of the tissue, and then passing to the phone camera’s image sensor.

Acknowledgements: We thank Dr. Frederic Michard from MiCo (michardconsulting.com) for help in manuscript preparation. With funding of Innosuisse—Swiss Innovation Agency, Project no. 32688.1 IP-ICT.

[Survey] Power Amplifiers Performance 2000-Present

Fifth web release on 2020/10/15: "PA_Survey_v5". This version-5 dataset includes PAs/transmitters from 500MHz to 1.5 THz in Bulk/SOI CMOS, SiGe, LDMOS, InP, GaN, GaAs technologies. The dataset contains total 3207 data points with over 1200 data points for CMOS, SiGe PAs and over 1500 data points for GaN, GaAs, InP PAs.

We have added sub-THz/THz power/signal generation circuits from 15GHz to 1.5THz, including PAs, fundamenal/harmonic oscillators, and frequency multipliers, to support the emerging research on beyond-5G/6G applications.

The file "PA_Survey_v5" is the version-5 dataset that includes ALL the reported PA/transmitter data since 2000 over frequency and various technologies. It also includes summary plots on CW Psat vs. Carrier Frequency for different technologies, peak PAE vs. CW Psat at different frequencies, and average PAE vs. average Pout for high-order complex modulations.

What is new in version-5 release beyond the version-4 release? 500MHz to 1.5 THz Power Amplifier designs and sub-THz/THz power/signal generation circuits published between 02/2020 and 10/2020.

• Cite this PA survey: Hua Wang, Tzu-Yuan Huang, Naga Sasikanth Mannem, Jeongseok Lee, Edgar Garay, David Munzer, Edward Liu, Yuqi Liu, Bryan Lin, Mohamed Eleraky, Sensen Li, Fei Wang, Amr S. Ahmed, Christopher Snyder, Sanghoon Lee, Huy Thong Nguyen, and Michael Edward Duffy Smith, "Power Amplifiers Performance Survey 2000-Present," [Online]. Available: https://gems.ece.gatech.edu/PA_survey.html
• Acknowledgement: We would like to sincerely thank many of our friends and colleagues for their helpful suggestions and insightful discussions.
• Feedback and Suggestions: We welcome your feedback and suggestions, including the ways to interpret and present the data. In addition, although we try to be as inclusive as possible when collecting these published data, it is certainly possible that we may miss some representative PA designs. Please feel free to send us feedback, suggestions, or missing PA papers.
• Contact: Please contact us through poweramplifiers.survey at gmail dot com. Do not use my gatech email address, since I may very likely miss your email.
• Source for this data collection: We focus on peer-reviewed and publicly accessible publications that are typical forums for PAs, including IEEE ISSCC, JSSC, RFIC, VLSI, CICC, ESSCIRC, IMS, T-MTT, TCAS, BCTM/CSICS (BCICTS in the future), APMC, EuMC, and MWCL. We also focus on public product datasheets on PAs/transmitters.