KAUST showcase Indium-Free Fully Transparent Electronics Deposited Entirely by ALD

Materials Science and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia has come up with a process to fabricate Indium-Free Fully Transparent Electronics Deposited Entirely by ALD. Below is the abstract fro the paper published recently in Advanced Materials.

Indium-Free Fully Transparent Electronics Deposited Entirely by Atomic Layer Deposition

Pradipta K. Nayak, Zhenwei Wang and Husam N. Alshareef
Version of Record online: 4 JUL 2016

Abstract:

Indium-free, fully transparent thin-film transistors are fabricated entirely by atomic layer deposition technique on rigid and flexible substrates at a low temperature of 160 °C. The transistors show high saturation mobility, large switching ratio and small subthreshold swing value. The inverters and ring oscillators show large gain value and small propagation delay time, indicating the potential of this process in transparent electronic devices.

Here is the ALD process flow for a fully transparent TFT display published accordingly in the Supporting Information that is free for download.

How a Flat Panel Display Works - An inside look

Here is an excelletn visual description oon "How a Flat Panel Display Works" that can be very useful for all of you into ALD ultra barriers for display applications:


"Ever wonder how your flatscreen television works? Well now you can take an inside look into the inner works of a flatscreen display!... READ MORE.

Check out this demo of the Lumineq TASEL made by ALD

At the end of 2012, Beneq acquired the Finnish-based electroluminescence business from US Planar Systems, Inc. The new display product brand is called Lumineq. Together with Beneq, Lumineq works closely on the industrial production and development of TASEL and TFEL technology and other atomic layer deposition (ALD) enabled products. The displays are ideal for high-end applications, where a subtle look and first-class viewing experience make the product stand out. 

Below is a new demo video of an Lumioneq TASEL display in action driving down a challenging road. It would be raelly cool if you could get one of those from Tom Tom or Garmin for any car.

NCD, a fast growing Korean ALD Equipment manufacturer for High Volume manufactuiring

As announced some weeks ago I am happy to have NCD as sponsor for the BALD Engineering ALD News blog. Here a review of the company and its fantastic ALD products follows and you should check the recently updated web page (http://www.ncdtech.co.kr/). NCD Co., Ltd. from Daejeon in Korea is a young and growing company founded in 2010 and is specialized in ALD original equipment manufacturing, which has been covered here on the ALD blog previously (here).

NCD is focusing on equipment development, process development, coating services, and process consulting for advanced ALD technologies for four business areas:

1. Solar
2. Display
3. Semiconductor
4. R&D

NCD has already had quite some successful years in entering the ALD equipment market and has built a very impressive customer base in Asia with main focus on the Korean domestic market, Japan, China and Taiwan.

As you may know, one of disadvantages of ALD is slow growth rate at typically an Å / cycle or so, that is to say ALD has a low throughput. In order to solve this problem, NCD has applied for patents for the high-throughput, high-volume and large-area every year. Based on these patents, NCD have developed their high-volume and large-area ALD system.

Here follows an overview of the ALD technology and equipment offering by NCD

1) High-volume ALD

   - GS ALD : surface passivation for c-Si solar cell                                                                         

   - MC ALD : dielectric for capacitor and encapsulation for micro display (OLED)

2) Large-area ALD

   - TS ALD : buffer layer for CIGS solar cell

   - GD ALD : encapsulation for OLED

Lucida^TM GS1200 ALD with automation system

NCD has paved the way for high volume manufacturing by a range of ALD systems (see above). Worth highlighting here is especially the Lucida™ GS1200 ALD system applied for high efficiency solar cells at both Hyundai Heavy Industries and LG Electronics etc. The GS series from NCD can realize Passivation for c-Si solar cell at an impressive through put of >3400 wph @ 10nm-Al2O3.

For the large area CIGS thin film soar and OLED display market, NCD has developed two main platforms - the TS and the GD series respectively. ALD chamber clustering is an approach used by many rather than large stand-alone batch tools. 

Lucida^TM GD600 ALD in R&D Lab.

Lucida™ GD series already had been applied to R&D centers of Korean and other customers, and showed the excellent performance for thin film encapsulation (TFE) and barrier applications. NCD is currently possible to run customer demoes with the large size of panel (1500mm x 1800) for using LucidaTM GD600 in the demo room (see above). NCD is the only place to do superior ALD demoes with that size panel.

It will be very exciting to follow NCD the next years when the ALD market continues its growth in many high-volume and large-area ALD applications.

Large area Self-Limiting Synthesis of Transition Metal Dichalcogenides by KEIT & Samsung Display

Here is a very interesting report from Korea Evaluation Institute of Industrial Technology (KEIT) supported by Samsung Display Co., Ltd. on self-limiting synthesis of an atomically thin, two dimensional transition metal dichalcogenides in the form of MoS2 for potential use in future display technology. The team was able to manufacture Large-area (~9 cm) mono-, bi-, and tri-layer MoS₂ on a SiO₂ substrate comparable in size to a cellular phone display screen.

Large-area (~9 cm) mono-, bi-, and tri-layer MoS₂ on a SiO₂ substrate comparable in size to a cellular phone display screen. (Picture From: Self-Limiting Layer Synthesis of Transition Metal Dichalcogenides, licensed under a Creative Commons Attribution 4.0 International License.)

As you all know ALD is a self-limiting growth method,however in this case where growth occurs by the formation of multi-layer islands it is difficult to achieve the layer controllability needed when compared to CVD.  That is why the research team states three important findings for ALD growth of 2D layer structured materials:

• Maximizing the self-limiting behavior of the ALD process to achieve layer controllability needed for a 2D structure by careful optimization of the process conditions (e.g., temperature, pressure, exposure of precursor/reactant)
• Careful selection of the precursor and reactant - in this study MoCl₅ and H₂S are used as the precursors.
• Understand the surface characteristics of the material being deposited.

Read all about it in the excellent open source report in published early this year in Scientific Reports:

Self-Limiting Layer Synthesis of Transition Metal Dichalcogenides 

Youngjun Kim, Jeong-Gyu Song, Yong Ju Park, Gyeong Hee Ryu, Su Jeong Lee, Jin Sung Kim, Pyo Jin Jeon, Chang Wan Lee, Whang Je Woo, Taejin Choi, Hanearl Jung, Han-Bo-Ram Lee, Jae-Min Myoung, Seongil Im, Zonghoon Lee, Jong-Hyun Ahn, Jusang Park& Hyungjun Kim

Scientific Reports 6, Article number: 18754 (2016), doi:10.1038/srep18754

This work reports the self-limiting synthesis of an atomically thin, two dimensional transition metal dichalcogenides (2D TMDCs) in the form of MoS2. The layer controllability and large area uniformity essential for electronic and optical device applications is achieved through atomic layer deposition in what is named self-limiting layer synthesis (SLS); a process in which the number of layers is determined by temperature rather than process cycles due to the chemically inactive nature of 2D MoS2. Through spectroscopic and microscopic investigation it is demonstrated that SLS is capable of producing MoS2 with a wafer-scale (~10 cm) layer-number uniformity of more than 90%, which when used as the active layer in a top-gated field-effect transistor, produces an on/off ratio as high as 108. This process is also shown to be applicable to WSe2, with a PN diode fabricated from a MoS2/WSe2 heterostructure exhibiting gate-tunable rectifying characteristics.

The Colors of Reliability - The ALD Displays from Finland

Lumineq^® Displays, a business unit of Beneq, a manufacturer and developer of thin film electroluminescent (TFEL) displays. Lumineq TFEL non-transparent displays are used in mining, marine, military, medical and many more demanding environments. TFEL displays are robust and reliable, and usually used in extreme environments, where traditional displays cannot cope with the conditions.

 

The black and yellow colors are inherent for thin film electroluminescent displays because of the technology (a ZnS:Mn phospor layer is the most efficient and its emissions are seen as yellow by the human eye), but we have been told that they are sometimes copied in demos of other display technologies to represent reliability. So strong is the mental connection between these colors and robustness for those in the business.

 

Read mor at the Beneq Blog : http://www.beneq.com/colors-of-reliability

Origin and History of Electro Luminescent Displays

As many of you know, Dr. Tuomo Suntola and co-workes invented many ALD technologies and processes and further developed Atomic Layer Deposition (ALD), then called Atomic Layer Epitaxy (ALE) to an industrial mass production process during the 70s and 80s. They did this in order to have a reliable manufacturing method with atomic level control of dopants and crystallinity of the individual thin film layers making up the EL device for producing Electro Luminescent Displays with reliable operation. Most ALD experts has com across this story numerous times and that is why it is interesting to read about it from a wider perspective. Here is an excellent article on the origin and history of EL Displays worth reading also including the early 20th century discoveries and work on electroluminescense and other big players like SHARP.

http://www.elwire.net/products/electroluminescent-displays/

For more ALD related information and History of they development that took place in Finland you should also visit the ADL 2014 Kyoto Tutorial by Riikka Puuronen (VTT, Finland) which is available at Slideshare: http://www.slideshare.net/RiikkaPuurunen/aldhistory-tutorial-in-kyoyo-al-dhistory-tutorialald2014riikkapuurunen20140615 (Slide above, Riikka Puurunen, VTT))

If you´re interest in more early history of ALD you should read about or join the VHPA Project - it is quite exciting!

Virtual Project on the History of ALD (VPHA)

VPHA is an open collaborative effort, whose goal is to clarify open questions related to the early history of the Atomic Layer Deposition (ALD) thin film deposition technique. VPHA was launched in July 2013. VPHA is based on voluntary efforts, and anyone interested in the history of ALD is welcome to join. All VPHA activities are made in an atmosphere of openness, respect and trust.

http://www.vph-ald.com

http://www.vph-ald.com