monolithic integration of algainp-based red and ingan-based green leds via adhesive bonding for multicolor emission

by:Getian     2020-08-08
Under normal circumstances, the whole color, inorganic light-
Cut from the respective Redgreen-blue (RGB)
A wafer consisting of inorganic crystal semiconductors.
Although this traditional method can achieve full color, this method is limited when applied to micro-displays that require high resolution.
Design a structure that can emit a variety of colors by integrating algaainp-Based on GA-
LEDs based on one substrate may be the solution to achieve high resolution full color.
Here, we introduce adhesive bonding and chemical wet etching processes to integrate two materials with different energy gap to achieve green and red glow.
We successfully transferred algaainp.
Red LED film based on InGaN
Based on green LEDs without any crack or void area, then separate the green and red sub-pixel LEDs horizontally;
Two-color LEDs integrated by combining technology can be tuned from the green area to the red area (530–630u2009nm)as intended.
In addition, we study them by deeply analyzing the light absorption of subpixel LEDs stacked vertically and the interaction between top and bottom pixels to achieve superHigh resolution. Inorganic light-
It is the brightest, most efficient and most stable light source for the display.
In the current display industry, inorganic LEDs are mainly used as thin-film-
Transistor Liquid
Red or crystal displaygreen-blue (RGB)
Sub-pixel outdoor LED display.
Recently, with interest in micro-displays such as smartphones, smartwatches and head-
Installed Display (HMDs)
Many efforts have been made to use efficient inorganic LEDs as a light source for miniature displays.
However, technical problems still exist when using inorganic LEDs as direct light sources (self-
Radiation light source)
For RGB full color micro-display.
The color of the light emitted by the inorganic LED is determined by the energy gap energy of the material in the active area.
In theory, the energy gap of InGaN can be from infrared (0. 69u2009eV)
Ultraviolet (3. 4u2009eV)
By changing the composition of In an alloy.
However, the InGaN quantum efficiency inside and outside-
Led-based led drops suddenly to the red spectrum area, so InGaN-
The base material is used only for green and blue emission sources.
Therefore, it is critical to combine InGaN with an efficient red light emitting material such as algaainp for RGB full-color display.
The traditional RGB LEDs are cut separately from each InGaNor AlGaInP-
Based on the wafer and arranged separately on the display panel, RGB pixels are formed through robot operation.
However, because it is difficult to pick up and place a large number of tiny rgb led pixels, the robot arm limits the scaling of the LED chip size to dozens of microns, which is not the right way to achieve high resolution (HR)microdisplays.
Recently, many studies have been carried out to achieve chip sizes below tens of microns by accurately and effectively arranging each red, green and blue LED.
Some research teams have already proved
Matrix and active-
Matrix LED micro-display by transferring 10 μm pixel film with elastic stamp.
Other research groups have proposed the transfer of many
Pixel films pick up and place pixel films by using components to control static or electrical properties.
Although the scaling problem is overcome by introducing a stamp, static or electrical method, during the LED transmission, the transmission will produce problems such as pixel loss on the display screen.
Also, these methods sometimes require highLaser Lift-costoff (LLO)
The process of removing the substrate of the extension layer.
Therefore, the alternative integration method without the transfer machine will help to achieve high
Resolution RGB Full Color Display in industrial environment.
One way can be done by Interface design such as: Nano-oxide/GaN, or something like n-p-
Although the lighting efficiency needs to be improved, improvements are still needed.
Another set of recommended stacked wafers
Grade III film-V-
Multi-color pixels based on led.
Here, we integrate two materials with different bandwidth through adhesive bonding and chemical wet etching process. The InGaN-
And algarn.
Overall integration for green and red emission based on led, respectively.
Our main strategy is to transfer the entire red LED extension layer to the green LED wafer and then split the pixels by manufacturing.
Unlike traditional methods, we are able to minimize the pixel size to a few micrometers, since our approach relies only on the exposure resolution.
In addition, compared with the existing method of separate and repeated transmission of each rgb led, it only needs to transmit the entire LED extension layer once, and the transmission efficiency is greatly improved.
Another advantage of our approach is to significantly reduce costs by excluding complex manufacturing steps such as LLO processes, and there is no need to use pick-
Up/transfer machine.
In addition, we can not only achieve sub-pixels arranged horizontally (LAS)-
Type Structure and sub-pixels stacked vertically (VSS)-
Type array structure, which improves the display resolution by three times that of LAS-type.
We have made two types of monolithic integrated red on Green led by using the combination technology of LAS-
Type and VSS-
Type array structure. For a LAS-
Structure, we analyze the optical and electrical properties of the integrated red and green pixels (
After bonding)
By comparing reference samples (before bonding).
By controlling the input power of each green and red sub-pixel, we are able to achieve multi-color emission from green to red wavelength.
In addition, we have studied light absorption and light emission in depth (PL)
Effect of VSS-
Type structure to minimize the interference effect of light and obtain a solid color of light emission.
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