China ’s Xiamen University and LatticePower Co LTD reported the characteristics of the micron -grade glow diode (LED) made of Aluminoma (Alingan) structures growing on silicon (SI). It focuses on their use in the display, especiallyIt is used for virtual reality and augmented reality (VR/AR) system [xi Zheng et al., Appl.phys.lett., V124, P051103, 20124].

"Few people study the color characteristics of the color characteristics of Ingan base red, green, and blue (RGB) micro -optical diode system that grows on the silicon base, which helps better understand the driver, back panel panel,The design of integration and heat dissipation. "



Figure 1: (A) The electrophoretic emitting emitting image of the red, green, and blue micro -glow diode (1 A/CM 2), with diameter of 8 μm and 20 μm, respectively.(B) Significant cross -section of red/green/blue micro LED.


Researchers use metal organic chemical gas deposition (MOCVD) on a 4-inch (111) to prepare the corresponding Micro-LED materials (Figure 1).

The LED with a diameter of 8 μm and 20 μm is made: the first step is to evaporate the deposit silver/titanium/tsar (AG/TI/W) on the P-GAN contact layer with electron beams.Flip the material and key to the (100) Si substrate, and remove (111) to grow the substrate.n The contact electrode consists of oxidation tin (ITO).Silicine (SIO2) is used for passivation.

Although the green and blue multi -quantum trap (MQW) active area uses an 8 -cycle structure with Ingan traps and GAN potential barriers, the red device has only three traps separated by Ingan separated by Aln/Algan/Gan.The purpose is to reduce the compatibility of the lattice and reduce the response of the high -puppet content.

The long wavelength red light transmission device has reduced performance.The current-voltage measurement shows the ideal factor (N, "ideal" = 1) with the wavelength increase: blue, green, and red micro-glowing diodes are 1.79, 2.60, and 3.08, respectively.The group commented: "When n is greater than 2, the reduction of load injection efficiency may be due to serious defect assisted unreasonable carriers, including trap auxiliary tunnels, load leaks, etc.The N value of N values is likely to be a non -radiation center induced by defects. "


Table 1: Micro-LED performance, 8 μm diameter.



Studies on the light emission of 8 μm diameter (Table B) and 20μm diameter (Table C) LED show that for the maximum performance of external quantum efficiency (EQE MAX) for long wavelength and small diameter.In addition, the semi -peak full width (FWHM) of the launch spectrum is wider for green and red devices.

The reduction of the performance of smaller devices is attributed to the importance of side wall damage, which leads to a larger non -radiation composite of electron and cave charge.


Table 2: Micro-LED performance, 20 μm diameter.




In addition, stronger quantum restrictions of the Stark effect (QCSE) and higher deficiency density in the higher tadpole content requires a longer wavelength to cause more serious declines.Maximum value.QCSE refers to a strong electric field in the strain semiconductor structure, from different charge polarization of chemical bonds in different layers.

The lower drooping effect in smaller devices is attributed to "better current gathering and heat dissipation in smaller Messa."

Because the shielding and filling effect of the built -in QCSE electric field effectively widened the band gap, the device also blue shift under the high current injection.

The researchers calculated the color performance of the combination and separate devices (Figure 2).Researchers use comparative standards for iTu-Recomgeten BT.2020 (REC.2020) and National Television Systems Commitee.The color triangle area and standard on the color map of the concept display of the RGB LED comparison comparison are compared (therefore it can exceed 100%).The coverage rate only includes the display area of the triangle relative to the internal area of the standard (therefore must be less than 100%).



Figure 2: (A) The current density density of the LED area ratio of the mixed RGB miniature LED system.(B) The coverage of REC. 2020 and REC. 2020 under different current density.(C) The relationship between the color purity and current density of a separate RGB micro -mortar diode with a size of 8 μm and 20 μm.

In terms of color purity of the RGB device, with the increase of the current injection, the color purity of the green LED has severely decreased.The group commented: "Because the color gamut of the RGB hybrid system is more sensitive to the color coordinates of the green self -luminous unit, the purity of 20 μm green micro -light diode is low, which will cause the area ratio and standard color gamut coverage of the RGB hybrid micro -optical diode systemRate decline. "

Researchers have also studied the heat stability of the device between 290K and 350K.The drift of 20 μm LED is greater than 8 μm LED.Researchers said that this shows that "the micro -glow diode with a reduction of Messa can show the stability of the superiors, which can be explained by better heat dissipation and higher color purity through 8 μm micro -light diode."