The documents EP2151852 and EP2151856 disclose a technology intended to form, on a substrate, islands of relaxed or partially relaxed crystalline semiconductor material. These islands can be used for the collective manufacture of light-emitting diodes (LEDs), as explained in detail in document EP2865021, for example.
Multiple products combine LEDs emitting at various wavelengths to form a colored light point. This is among others, the case for display screens that enable an image consisting of pixels to be formed, each pixel combining a red, a green, and a blue LED, whose emission can be controlled individually to form a light point of the selected color, by combining light emissions.
The LEDs that are combined to form the pixel are generally not manufactured from the same materials and using the same technologies. Thereby, blue or green LEDs may consist of nitride (with the general formula InGaN) and red LEDs of phosphide (with the general formula AlGaInP). Manufacturing a screen involves the assembly of the diodes, one-by-one, to form the pixels of the final device, e.g., using a pick-and-place technique.
Since the materials do not have the same properties, the characteristics pertaining to the aging, thermal/electrical behavior, and/or efficiency of the devices that use them are generally very different. These variabilities must be taken into account when designing a product that includes LEDs consisting of different materials, which may sometimes render the design very complex.
Other solutions provide for forming the pixels from diodes that are all identical, manufactured on the same substrate and/or using the same technology. Monolithic micro-LED panels having a reduced size and a high resolution can then be realized. By way of example of such a realization, one may refer to the document entitled “360 PPI Flip-Chip Mounted Active Matrix Addressable Light Emitting Diode on Silicon (LEDoS) Micro-Displays,” Zhao Jun Liu et al., Journal of Display Technology, April 2013. The light radiation emitted by the micro-panel's LEDs can be chosen in the ultraviolet range and selectively converted, from one diode to another, to various wavelengths in order to correspond to red, green, and blue light emissions so as to form a color screen. This conversion can be achieved by placing a phosphorescent material on the emitting face of the LEDs. However, the conversion consumes light energy, which reduces the quantity of light emitted by each pixel and thus the efficiency of the display device. It also requires dispensing the phosphorescent materials on the emitting surfaces of the LEDs, which renders the manufacturing method of these micro-panels more complex.
In order to overcome the limitations discussed above, it would be desirable to be able to simultaneously manufacture, on the same substrate, using the same technology, LEDs capable of emitting in different wavelengths. More generally, it would be advantageous to collectively manufacture devices having optoelectronic properties that are different one from another.