According to Straits research, the market size of micro LED displays is expected to grow at a CAGR of 88.60% in eight years, that is between 2023 and 2031. Such rapid growth indicates that this technology is at its inflection point. Yet, this technology is uncommon. This article aims to cover everything you need to know about micro LEDs.
What are micro LED lights?
The performance of display technologies has improved drastically over the years. They have become better at power consumption, picture quality, and size. As the main aspect that controls picture quality, pixel configuration has undergone a lot of modification to achieve today’s standards.
LED is particularly one of the display technologies shaping the landscape. It has been used to manufacture pixels that emit bright light to illuminate screens.
The pixelation and image quality of a display is influenced by the size of LED lights. As such, the smaller the better. With this knowledge, display manufacturers have relentlessly looked into ways to make LEDs smaller.
Through constant research, micro LED lights were developed. As the name suggests, micro LEDs are microscopic. For comparison, they are a tenth the size of human hair. They are so small that they’re invisible to the naked eye. Micro LEDs are also known as μLED.
Micro LED lights are self-illuminating semiconductors that form the pixels of a micro LED display. Each micro LED pixel has a red, blue, and green light. This configuration has many advantages as you will see throughout the article.
How micro LED lights are manufactured
As you would expect, creating microscopic devices is quite challenging. However, engineers have successfully adopted techniques that allow them to grow and transfer micro LED lights to a display panel. Epitaxy is the common technique used to grow micro LEDs.
Epitaxy is a method of growing a thin film of crystalline atoms on top of a substrate material. This technique is especially used in nanotechnology to grow Optoelectronic devices such as micro LED lights.
Growing micro LEDs using epitaxy
Epitaxy is a method used to grow crystals on other crystals. Micro LEDs are grown as crystals. Sapphire is the crystal used to grow micro LEDs on epitaxial wafers. This process is complex but effective.
Micro LEDs are made using group III and IV elements of the periodic table. They include indium gallium nitride (InGaN) alloys and aluminum gallium indium phosphide (AlGaInP) alloys. The common epitaxy approaches used to grow micro LEDs are Chemical vapor deposition epitaxy and Molecular beam epitaxy.
Chemical vapor deposition (CVD) epitaxy
This is among the most widely used epitaxy techniques to grow micro LED semiconductors on sapphire wafers. Specifically, a type of CVD known as metal-organic vapor deposition (MOCVD) is used to grow the micro LED crystals.
Metal-organic CVD is carried out in an enclosed chamber that contains a gas flow inlet, substrate chamber, vacuum pump, and other essential components. The reaction leads to the formation of GaN semiconductors on the sapphire wafers.
Chemical vapor deposition works by reacting gasses over an electrically or thermally charged wafer — sapphire. The reaction between the gasses and the charged wafer leads to the development of a thin film containing atoms of GaN. These films need to be cooled and prepared for mass transfer.
Molecular beam epitaxy (MBE)
This is another technique used to manufacture micro LED semiconductors. The MBE chamber contains effusion cells that convert gallium and arsenide into their vapourised form. This conversion is facilitated by heating the compounds.
Inside the MBE epitaxy chamber, an ultra-high-vacuum environment is created. This vacuum atmosphere is meant to prevent the collision of atoms and also prevent foreign molecules from taking part in the reaction.
The effusion cells start projecting molecular beams of the vapourised compound onto the sapphire substrate. Effectively, this forms a thin film of gallium arsenide (GaAs) on it. GaA is the semiconductor material that is then transferred to the display and arranged depending on its color to form a complete micro LED pixel.
Common Micro LED Mass Transfer Methods
Successfully grown micro LED semiconductors need to be transferred to the backplane of the display. In most cases, this backplane is made of inorganic glass material. The transfer of micro semiconductors is a delicate process that requires utmost care to avoid damaging the microdevices.
Mass transfer methods need to be effective. In other words, they need to be highly accurate, cost-effective and have a high transfer yield. The following are some of the techniques used to transfer micro LEDs to the backplanes.
Pick and place method
This term is generally used to describe manual or automated methods of mass transfer of micro semiconductors from wafer to substrate. A common automated pick-and-place technique is laser-assisted transfer.
In this technique, a laser lifts off the grown semiconductors from the epitaxy wafer. Then, the substrate is placed under a projection beam which transfers the RGBs. Laser-assisted transfer is among the most effective methods in terms of accuracy, speed, and yield.
Fundamentally, this technique involves the transfer of micro LED semiconductors to a substrate using electrostatically charged transfer heads. Methods such as field emission are used to charge the substrate. By leveraging the repulsion and attraction forces of electrostatics, engineers are able to transfer millions of LEDs per hour.
This technique involves placing the wafers that contain the LED chips on a rolling device, then running it over a substrate. Then, this rolling movement imprints the LED microchips on the substrate. The roll-to-roll technique has a high yield and transfer rate. This technique was developed by the KIMM Institute.
Fluidic self-assembly method
This technique is among the most economical but it has a low transfer yield. Its mechanism involves the use of water as an assembly medium. Using fluid mechanics, the assembly medium uses dispersion to suspend the LED chips and then transfer them to the substrate material. Clearly, this technique is risky and ineffective.
Features of Micro LED Lights
Micro LED chips have quite unique features. These features are what contribute to the superior quality micro LED displays. Some of them include;
Full-array local dimming
Contrast is among the many aspects that influence the image quality when watching content on a large display. It is defined as a ratio of the brightness of whites and darkness of dark colors on an image. The type of display technology is among the factors that influence contrast.
On the other hand, full-array local dimming is a feature that high-pixel density displays have to promote better contrast. Local dimming technology assigns zones on the LED architecture that light up independently based on the color of an image.
Since the display is entirely made up of LED chips, dimming occurs throughout the display. This is opposed to the edge-lit dimming approach which lights up or dims along the edge of a display.
High brightness levels
The brightness of a display depends on factors like the source of light. In LCD or OLED displays, LED lights are used as a backlight for the main display. This approach limits the brightness of the screen to the LED backlights,
Micro LED displays use micro LED chips as the main lights. In other words, this display technology does not use a backlight. Doing so increases the light coming from the screen, thereby promoting brightness levels. Additionally, micro LEDs are packed in millions due to their size. This means high pixel density, which translates to high brightness levels.
Lastly, the inorganic compounds used to make micro LED chips — gallium nitride — can handle high brightness levels without losing quality. Reportedly, micro LED displays can reach brightness levels of up to 5000 nits.
Technically, inorganic materials have stronger molecular bonds. This property contributes to their durability. Since micro LED chips are grown using inorganic compounds, you would expect them to be durable. More specifically, the GaN compounds are immune to the degrading effects of temperature and moisture.
Additionally, the micro LEDs are independent. This means they function without relying on each other, which alleviates the risk of breaking down. It’s one of the reasons micro LED displays are less prone to developing burn-in effects.
Flip-chip LED bonding
One of the core factors that determine the performance of an LED display is chip packaging technology. This entails the method used to align the LEDs on the substrate so as to allow them to receive electric currents from the system.
Flip-chip LED bonding is one of these packaging techniques. This packaging technique ensures that LED chips are attached directly to the electric board with the signal receiver facing down. By doing so, the manufacturer ensures that the chips get charged directly, thereby increasing their response time drastically.
Fast response time
An LED’s display response time is controlled at the chip level. This means the properties of the specific LED used to affect the response behavior of the display. Micro LED lights are known to have fast response times.
The flip-chip LED bonding is one of the reasons for the fast response times. To clarify, the response rate being referenced is the rate at which a display responds to an input signal. This feature impacts aspects like the refresh rate, motion handling, and so on. Also, micro LED lights are able to receive and translate electric current quickly.
As the display technology of the future, you would expect LED displays to have improved energy consumption capabilities. Luckily, that is the case. Features like local dimming, fast switching, automatic power control, and other techniques are responsible for the efficient consumption of power.
Additionally, unlike other display technologies, micro LEDs do not dissipate heat, a factor that contributes to energy wastage. Other LED and display technologies generate a lot of heat which needs to be dissipated to avoid overheating the display.
No screen burn-in
Have you ever observed an imprint on a turned-off display? These imprints are known as burn-ins. They are a result of extended usage. Most commonly, burn-in effects are observed in OLED displays.
The inorganic nature of micro LED chips counteracts the possibility of displays developing burn-ins. For one, these chips are far advanced to handle issues that cause burn-ins. Issues like prolonged usage have no adverse effects on micro LED lights. Also, the fast response rates of micro LEDs contribute to lowering the occurrence of burn-in effects.
Benefits of micro LED displays
The culmination of the above features of LED lights contributes to reliable display technologies that offer value for money. Some of the benefits that you should expect from a micro LED display include.
While micro LED technology is relatively new, some manufacturers have demonstrated the capabilities of this concept. Most of the features we discussed above have been seen in action, which has confirmed the hype.
The only drawback to this technology is the high production cost required. It is expensive to grow and transfer micro LEDs. However, trends have shown that the costs will eventually go down with time.
Wide Viewing Angles
The ability to view content clearly from multiple directions is quite beneficial. Micro LED displays have this advantage for various reasons. For one, the high pixel density contributed to by microscopic LEDs increases the clarity of the display. This is important especially when the display is meant to be used by broad audiences.
Wide Color Gamut
Color gamut is the range of colors reproduced by a display. Micro LED displays have wide ranges of colors for various reasons. For instance, the lack of a color filter in the display configuration removes effects such as color loss. This ensures that colors appear as real as possible to the human eye.
Flexible Designs and Size
Micro LED displays are manufactured in modules or panels. This approach gives the manufacturer the freedom to configure displays in any size. Micro LED lights also do not limit the shaping of LED displays. This freedom ensures that you get to customize a display based on your preferences.
Challenges of Micro LED Lights
Aside from all the riveting benefits that come with micro LED technology, there are expected setbacks. While these challenges are expected, there are projections that most of them will be solved as the technology matures. Here are the current challenges facing this display technology.
Some Transfer Methods are Slow and Inaccurate
Mass transfer of micro LEDs from epitaxial wafers to the substrate is an integral step in the fabrication process. This means that it accounts for quality, manufacturing speed, and other equally vital success indicators.
Semiconductor transfer methods such as the fluidic self-assembly method are slow and inaccurate. As such, it ends up producing low-quality displays. Not to mention, at quite low rates. From a business perspective, you can already tell this is a challenge. It will lower productivity and lead to a loss of investments.
Micro LED Modules are Expensive
Like any business transaction, manufacturers use production cost as one of the factors to price their products. The cost of producing micro LED lights was relatively high at the time this article was published.
Research and development is one of the reasons this technology is currently expensive. It costs a lot since this phase is mostly about trial and error. Also, this technology has not matured for mainstream retail. In other words, large-scale production—which has the benefit of reducing production costs—is limited.
The complexity of the production process of micro LEDs is another reason why these displays are expensive. For starters, it requires state-of-the-art machines, skilled personnel, and rare crystals. The challenge is that there is no walkaround to avoid these costly resources at the moment.
The Technology is in its Early Phases
There is a direct correlation between the cost of technology and its current production state, at least according to past trends. Micro LED is no exception. Most of the investment being channeled to this technology is being used to fund research and prototyping. You are smart enough to know that R&D does not yield profits right away.
Moreover, the fact that the technology is in its infancy means that almost everything is made from scratch. There are no playbooks to reference from, and support from the industry leaders could be limited. However, private investment could revolutionize this technology and contribute to its affordability.
Comparing Micro LEDs vs Other Display Technologies
How does micro LED compare to existing display technologies? This is a concern that most people have, and so should you. The reason is that you need to compare it against what is in the market to help you get a sense of its relevance. Let us compare micro LED technology to three of its major competitors.
Micro-LEDs vs LCD
LCD is among the oldest display technologies in the market. However, it has undergone significant modifications that have improved its performance by far. LCD uses liquid crystals and a backlight to illuminate a display. The backlighting clearly makes this technology inferior to micro LEDs.
Micro-LEDs vs OLED
OLED displays use organic LED semiconductor chips to light up an LCD panel. It is among the latest and most well-performing display technologies in the market. However, it faces challenges of low pixel densities and burn-in effects. If you have to choose between OLED and micro-LED with a fixed budget, OLED would be your best choice.
Micro LED vs Mini LED
Essentially, this is the middle ground. Mini LEDs are smaller than regular LEDs, but larger than micro LEDs. These LEDs are less than 2mm in size, which makes them visible to the naked eye. The major difference between them and micro LEDs is that they are used for backlighting. This is as opposed to micro LEDs which are integrated directly on the screen.
The Future of Micro LED Technology
Undoubtedly, the next phase of display technologies will be shaped by the features exhibited by micro LEDs. There are many fields that would benefit from high-performance technologies such as micro LEDs. While we cannot foretell the future, the odds are in favor of some of the following occurrences.
Integration in wearable devices
In the last few decades, wearables such as smartwatches, smart glasses, and virtual reality headsets have gained tremendous traction in mass media. A lot of resources are being channeled to these technologies to support innovation. Better displays are one of the innovation agendas in this sector.
Micro LED technology has the potential to revolutionize wearables displays. For instance, reports have revealed that Apple intends to manufacture LED displays for their smartwatches in a few years. As this technology becomes more accessible, there is a high possibility of more wearables benefiting from the properties of micro LED lights.
Essentially, optogenetics is a technique where nerve cells can be controlled with light. It sounds straightforward but it is a delicate procedure. The takeaway is that scientists can create visual aids using micro LED technology. This is an exciting milestone in the quest to find better solutions to vision defects such as partial blindness.
Organizations like Science Corp. are pioneering promising technologies to restore common eye defects using micro-LED technologies. Micro LED is best suited for this innovation due to its high resolution which is the closest we have to real-life vision.
High-speed LiFi internet
Currently, most light fidelity (LiFi) uses regular LED lights for this internet technology. The adoption of micro LEDs is inevitable and will revolutionize LiFi. Features such as high bandwidth and fast response rate make micro LEDs a strong candidate for LiFi.
The future of micro LEDs is not limited to the above. This is because micro LED lights have tons of highly reliable characteristics. Organizations are pulling resources to fund R&D projects that will constitute the next phase of this technology.
The world is currently witnessing technological advancements in many areas. As displays are poised to become primary communication mediums in the future, micro LEDs will be pivotal in shaping this landscape. Exploring the features, benefits, challenges, and potential of this technology has confirmed that micro LED lights are the next big thing.
How much does a Micro-LED cost?
The cost of micro LEDs is dependent on several factors. Averagely, prices will range from $5,000 to 10,000 for 10 – 15 inch panels. High prices are anticipated and valid given the production costs of this technology. But as trends indicate, their prices will eventually become more accommodating for mainstream consumers.