FACEBOOK TECHNOLOGIES, LLC (Menlo Park, CA)
A micro-LED is characterized by a small chip size. A micro-LED’s linear dimension may be as small as 50 mm or 10 mu.m. The dimension of the linear can be as tiny as two .mu.m or 4 .mu.m.
The efficiency of micro-LEDs could be affected by the lateral diffusion. When current is injected into an LED electrons diffuse across a variety of directions. Due to the small size, the majority of electrons are lost in the vicinity of the micro-LED. This is known as surface recombination. The electrons that are lost do not contribute to the generation of light from the micro-LED. This is particularly so when the electrons’ diffusion length is close to the linear dimensions of the micro-LED.
The present disclosure is focused on reducing the loss of surface recombination in micro-LEDs. One method is to increase the bandgap of a semiconductorlayer’s outer region by implanting ions in the. Then the region around it is annealed in order to mix the ions with the atoms in the semiconductor layer. The semiconductor layer includes an active layer of light emitting. The light-outcoupling surface of the semiconductor layer has a diameter of less than 10 .mu.m. The semiconductor layer’s outer layer extends from the semiconductor layer’s exterior surface to the central region of its semiconductor layer, that is shaded by amask upon the implantation of the ions.
A semiconductor layer may include an n-side semiconductor surface, which is located adjacent to the light-outcoupling surface and a p-side semiconductor layer opposite the active layer that emits light. Ions can be implanted from a top surface of the p-side layer to an approximate depth of 460 nm within the semiconductor layer. In addition, or alternatively to the above procedure the ions may be implanted within the active light emitting layer from the top of the P-side semiconductor.
The ions could comprise Al ions. The amount of Al may vary between 0.3 to 0.5 in the semiconductor layer’s outer region. The ions may have an implantation energy of around 400 keV. The ions can be implanted with an angle between0.degree. Between 0.degree. and 7.degree. Referring to an axis that’s normal to the mask plane.
A mask could comprise a metal, resist, or hard mask. The thickness of the metal can be as low as 1000 nanometers. The thickness of the resist may be less than 2500, while the thickness of the hard mask may be lower than 800. The outermost portion of the semiconductor layer could be formed in an annular cross-section.
In some embodiments the light-emitting diode could contain a semiconductor with an active coating for light emission. The light-outcoupling surface of the semiconductor layer has a radius that is less than 10 .mu.m. A bandgap within an outer region ofthe semiconductor layer is larger than a bandgap in a central region of the semiconductor layer. The region that surrounds the semiconductor layer comprises ions implanted in the region outside of the semiconductor layer and intermixed with atoms inside the semiconductor layer’s outer region. The light-emitting device can be created using the method described above.
This summary is neither intended to define the key or most essential characteristics of the claimed subject matter It is not intended to be used alone to determine the scope of the subject matter claimed. Take a look at the entire scope of this disclosure, all illustrations and all claims to understand the subject matter. The foregoing, together with other features and examples, will be described in more detail below in the following specification,claims, and accompanying drawings.Click here to view the patent on USPTO website.
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