A micro-light-emitting diode (micro-LED) includes a first type semiconductor layer, a second type semiconductor layer, a dielectric layer, and electrodes. The second type semiconductor layer is disposed on or above the first type semiconductor layer. The dielectric layer is disposed on the second type semiconductor layer. The dielectric layer includes openings therein to expose parts of the second type semiconductor layer. The electrodes partially are disposed on the dielectric layer and respectively electrically coupled with the exposed parts of the second type semiconductor layer through the openings of the dielectric layer, in which the electrodes are separated from each other.

BACKGROUND

1. Technical Field

The present disclosure relates to micro-light-emitting diodes (micro-LEDs).

2. Description of Related Art

Electronic devices increasingly include display screens as part of the user interface of the device. As may be appreciated, display screens may be employed in a wide array of devices, including notebook computers and handheld devices, as well as various consumer products, such as smart phones and tablet personal computers. Some of those devices result in the screen display being used under a variety of environmental conditions. One example is having a display screen mounted within an automobile. A driver's or passenger's ability to view the screen while traveling in a vehicle is affected by the outside light conditions, for example. Different levels of screen brightness are required during daytime hours as compared to nighttime hours. Accordingly, there is a need for an efficient and relatively simple way of adjusting the brightness of a display screen in response to ambient light conditions.

In the recent years, light-emitting diodes (LEDs) have become popular in general and commercial lighting applications. Accordingly, since the screen displays are used under a variety of environmental conditions, high ambient light conditions or low ambient light conditions, a wider dynamic range of the LEDs brightness output becomes important in display screens.

However, in the current density versus voltage (J-V) characteristics of an LED, current density is approximately an exponential function of voltage near the threshold, so a small voltage change may result in a large change in current density. Further, the I-V characteristics is determined by the following equation I:

I=I0⁡(exp⁡(q⁡(V-Irs)nKT)-1)equation⁢⁢I
where I is the current through the LED, I0is the maximum current for a large reverse bias voltage (reverse saturation current), q is the electron charge, V is the voltage across the diode, rsis the series resistance, k is Boltzmann's constant, and T is the absolute temperature.

In addition, one disadvantage of the conventional LEDs is that the LEDs have a wide range of operating current density, and the J-V curve of the LEDs is nonlinear as the current density is too low or too high. When the current density is too low, the forward voltage of each of the LEDs is different from others due to the difference produced by the manufacture process, and hence the brightness uniformity of the LEDs is difficult to control. When the current density is too high, the conversion efficiency of the LEDs is low due to the thermal issue.

Furthermore, if the voltage is below the threshold or on-voltage no current will flow and the result is an unlit LED. If the current density is too high the current will go above the maximum rating, the result is overheating and potentially destroying the LED. Therefore, the LED brightness is difficult to be controlled linearly due to the above reason.

SUMMARY

According to one embodiment of this invention, a micro-light-emitting diode (micro-LED) includes a first type semiconductor layer, a second type semiconductor layer, a dielectric layer, and electrodes. The second type semiconductor layer is disposed on or above the first type semiconductor layer. The dielectric layer is disposed on the second type semiconductor layer. The dielectric layer includes openings therein to expose parts of the second type semiconductor layer. The electrodes partially are disposed on the dielectric layer and respectively electrically coupled with the exposed parts of the second type semiconductor layer through the openings of the dielectric layer, in which the electrodes are separated from each other.

DETAILED DESCRIPTION

FIG. 1is a cross-sectional view of a micro-light-emitting diode (micro-LED)100according to the first embodiment of this invention. The micro-LED100includes a first type semiconductor layer110, an active layer150, a second type semiconductor layer120, a dielectric layer130, a first electrode140a, and a second electrode140b. The second type semiconductor layer120is disposed above the first type semiconductor layer110. The active layer150is disposed between the first type semiconductor layer110and the second type semiconductor layer120. The dielectric layer130is disposed on the second type semiconductor layer120. The dielectric layer130has a first opening O1and a second opening O2therein to expose parts of the second type semiconductor layer120. The first electrode140aand the second electrode140bare partially disposed on the dielectric layer130and are electrically coupled with the exposed parts of the second type semiconductor layer120through the first opening O1and the second opening O2, respectively, in which the first electrode140aand the second electrode140bare separated from each other.

By the aforementioned configuration, electric potential of the first electrode140aand the second electrode140bcan be individually controlled, such that current I1and current I2which are independent of each other are respectively generated. The current I1flows along a path from the first electrode140ato the active layer150through the first opening O1and the second type semiconductor layer120, and the current I2flows along another path from the second electrode140bto the active layer150through the second opening O2and the second type semiconductor layer120. Since the brightness of the micro-LED100is proportional to intensity of the current flowing through the micro-LED100, individually controlling the electric potential of the electrode140aand the second electrode140bfor generating independent currents varies the brightness of the micro-LED100.

For example, one of the current I1and the current I2flows through the micro-LED100to provide low brightness. On the contrary, the current I1and the current I2flow through the micro-LED100simultaneously to provide high brightness. By controlling the number of the electrodes and openings with the current flowing, the total current flowing the micro-LED100and the brightness of the micro-LED100are correspondingly varied.

Further, individually controlling the electric potential of the first electrode140aand the second electrode140bincludes controlling the potential difference between the electrodes, including the first electrode140aand the second electrode140b, and the first type semiconductor layer110. For example, when the electric potential of the first electrode140ais controlled to be V1, the electric potential of the second electrode140bis controlled to be V2, the electric potential of the first type semiconductor layer110is V3, and V1≠V2=V3(for example, V1>V2=V3), only the current I1is generated. Similarly, when V2≠V1=V3(for example, V2>V1=V3), only the current I2is generated. Furthermore, when V1=V2≠V3(for example, V1=V2>V3), the current I1and the current I2are generated simultaneously.

In addition, the first opening O1and the second opening O2have different areas, in which the first opening O1has an area A1and the second opening O2has an area A2, and A2>A1. Therefore, when the micro-LED100is operated within a linear current density range from J1to J2, the first opening O1with the area A1and the second opening O2with the area A2are dimensioned to allow the current flowing through the micro-LED100to be controlled within a continuous current range from A1*J1to (A1+A2)*J2.

FIG. 2is a continuous current range of the micro-LED ofFIG. 1. The horizontal axis ofFIG. 2is the relative current intensity. As shown inFIG. 1andFIG. 2, the total current flowing through the micro-LED100, the current I1, and the current I2are marked as ranges170,171, and172, respectively.

In some embodiments, the current I1is in a range from A1*J1to A1*J2(the range171from a to b inFIG. 2), the current I2is in a range from A2*J1to A2*J2(the range172from c to d inFIG. 2), and A1*J2>A2*J1, such that the ranges171and172of the current I1and the current I2are overlapped. Since the total current flowing through the micro-LED100is superposed by the current I1and the current I2, the range170(from a to e inFIG. 2) of total current flowing through the micro-LED100superposed by the ranges171and172, which are overlapped, is continuous. Therefore, the current range of the micro-LED100is continuous. In addition, since the range170is superposed by the ranges171and172, the length of the range170, from a to e, is the sum of the length of the ranges171and172, from a to b and from c to d, respectively.

Similarly, since the current flowing through the micro-LED100is controlled within the continuous current range from A1*J1to (A1+A2)*J2, the brightness of the micro-LED100is proportional to the continuous current range from A1*J1to (A1+A2)*J2. In other words, the brightness of the micro-LED100is continuous and is controlled in a range, which is dependent on the dimension of the first opening O1and the second opening O2and the current density J1and J2.

FIG. 3is a plan view of the micro-LED100ofFIG. 1, wherein the electrodes are removed. As shown inFIG. 1andFIG. 3, the first opening O1and the second opening O2are substantially the same. Therefore, the following description is taking the first opening O1as an example, and the structural details of the second opening O2are similar to that of the first opening O1.

The first opening O1defines the contact interface between the first electrode140aand the second type semiconductor layer120. When the micro-LED100is forward biased, charge carriers (or current) flow from the contact interface between the first electrode140aand the second type semiconductor layer120to the active layer150.

In some embodiments, a second shortest distance D2between an edge of the first opening O1and a side surface122of the second type semiconductor layer120is greater than or equal to 1 μm. Since the second shortest distance D2is greater than or equal to 1 μm, charge carriers spreading to the side surface122and/or a side surface152of the active area150are rare or none. Therefore, the non-radiative recombination occurring at the side surface152can be reduced, thereby increasing the efficiency of the micro-LED100.

Furthermore, since the first opening O1limits the area where the current goes into the micro-LED100, the current density within the emitting area of the micro-LED100increases and can be uniform, thereby increasing the efficiency of the micro-LED100.

Moreover, since charge carriers spreading to the side surface122and/or the side surface152are rare or none, the leakage currents of the micro-LED100can be reduced regardless of the lattice defects in the side surface122and/or the side surface152.

Furthermore, since the first opening O1makes the emitting area of the micro-LED100smaller than the size of the micro-LED100, it is possible to continue miniaturization of the emitting area of the micro-LED100while remain the size of the micro-LED100to allow the micro-LED100to be manufactured with acceptable yield rate. For example, a 20 μm×20 μm micro-LED100with a 2 μm×2 μm opening can perform the same light output characteristics as a 2 μm×2 μm micro-LED. In addition, the micro-LED100with a larger size has a considerably lower electrostatic sensitivity, a considerably lower surface leakage current, and a considerably lower side surface leakage current due to the lattice defects. In some embodiments, the size of the micro-LED100is smaller than 100 μm×100 μm or 0.01 mm2.

In some embodiments, a geometric weighted mean distance between the edge of the first opening O1and the side surface122is greater than or equal to 1 μm. Similarly, since the geometric weighted mean distance between the edge of the first opening O1and the side surface122is greater than or equal to 1 μm, charge carriers spreading to the side surface122and/or a side surface152of the active area150are rare or none.

Further, the total area of the openings of the dielectric layer130viewed in a direction normal to the dielectric layer130occupies 1%-95% of the total area of the micro-LED100viewed in the direction normal to the dielectric layer130. If the total area of the openings occupies less than 1% of the total area of the dielectric layer130, at least one of the openings may be too small, and therefore a complex photolithography process may be needed. If the total area of the openings occupies greater than 95% of the total area of the dielectric layer130, the second shortest distance D2may be less than 1 μm, thereby allowing charge carriers to spread to the side surface122and/or the side surface152.

In some embodiments, a first shortest distance D1between the first opening O1and the second opening O2, which are adjacent openings, is greater than or equal to 0.5 μm. Since the first shortest distance D1is greater than or equal to 0.5 μm, the paths of the current I1and the current I2are separated by a space. Therefore, the paths of the current I1and the current I2keep independent of each other.

In addition, the first opening O1and the second opening O2in this embodiment have different areas, but are not limited thereto. For example, in some embodiments, the first opening O1has an area A1, the second opening O2has an area A2, and A1≦A2. That is, all the openings of the dielectric layer130have the same shape or have different shapes.

FIG. 4is a current density-voltage curve of a micro-LED. During operating a micro-LED, the J-V curve is approximately regarded as two regions, in which one region is a linear region160and the other one is a nonlinear region162. In the linear region160, when the voltage is increased, the current density from J1to J2is increased linearly. In the nonlinear region162, when the voltage is increased, the current density below J1is increased substantially at the threshold. In other words, the current density of the micro-LED in the linear region160from J1to J2is easier and steadier to be controlled than in the nonlinear region162.

As shown inFIG. 3andFIG. 4, in some embodiments, the first opening O1and the second opening O2of the dielectric layer130are dimensioned to allow the micro-LED100to be operated in a linear region160of the J-V curve. For example, assuming current for driving the micro-LED100is set at 10 μA, a 50 μm×50 μm micro-LED and a 50 μm×50 μm micro-LED with a 100 μm2total area of openings are compared in the following. In the 50 μm×50 μm micro-LED, the corresponding current density is calculated as 0.4 A/cm2(10*10−6/50*50*10−8). In the 50 μm×50 μm micro-LED with the 100 μm2total area of the openings, the corresponding current density is calculated as 10 A/cm2(10*10−6/100*10−8). Since the micro-LED with the openings has the greater current density under the same current, the micro-LED with the openings is easier and steadier to be controlled than the micro-LED without openings due to avoiding near the threshold. Therefore, with this characteristic, the current flowing through the micro-LED100in the range from A1*J1to (A1+A2)*J2can be controlled steadily.

Reference is made back toFIG. 1. In some embodiments, the current spreading length of the second type semiconductor layer120is less than the current spreading length of the first type semiconductor layer110. That is, the current spreading length of the first type semiconductor layer110is greater than the current spreading length of the second type semiconductor layer120. In some embodiments, the current spreading length of the first type semiconductor layer110is over 20 times greater than the current spreading length of the second type semiconductor layer120. In this configuration, charge carriers in the second type semiconductor layer120are more difficult to spread to the side surface122and/or the side surface152. Therefore, the non-radiative recombination occurring at the side surface152can be further reduced, thereby further increasing the efficiency of the micro-LED100.

The current spreading length of a semiconductor layer of a diode is determined by the following equation II:

Ls=tnideal⁢KTρ⁢⁢J0⁢eEquation⁢⁢II
where Lsis the current spreading length of the semiconductor layer of the diode, t is the thickness of the semiconductor layer, nidealis the ideality factor of the diode, K is the Boltzmann constant, T is the temperature of the semiconductor layer in Kelvin, ρ is the resistance of the semiconductor layer, J0is the current density at the interface between the semiconductor layer and a electrode of the diode, and e is the charge of a proton.

As confirmed by the aforementioned equation I, the current spreading length of the semiconductor layer of the diode is proportional to

tρ.
Therefore, in some embodiments, the first type semiconductor layer110has a resistance ρ1and a thickness t1, the second type semiconductor layer120has a resistance ρ2and a thickness t2, and

t2ρ2<t1ρ1
to make the current spreading length of the second type semiconductor layer120to be less than the current spreading length of the first type semiconductor layer110. In some embodiments, the first type semiconductor layer110is an n type semiconductor layer, and the second type semiconductor layer120is a p type semiconductor layer.

In addition, the IV curve for a micro-LED may have a steep slope of the forward current versus the forward voltage especially in the mid/low power region near the threshold. This steep slope makes it difficult to control the forward current, and thus the brightness of the micro-LED cannot be easily controlled.

Therefore, in some embodiments, the dielectric layer130with the openings is disposed on the second type semiconductor layer120, which has a short current spreading length. Since the second type semiconductor layer120has the short current spreading length, the second type semiconductor layer120has high resistance and is thin in thickness. In this configuration, the serial resistance of the micro-LED100increases, thereby making the slope of the forward current versus the forward voltage gentle. This gentle slope makes it easier to control the forward current, and thus the brightness of the micro-LED100can be more easily controlled.

In some embodiments, the first type semiconductor layer110is made of, for example, n-doped GaN:Si. The thickness of the first type semiconductor layer110is in a range from 0.1 μm to 50 μm. The first type semiconductor layer110is formed by, for example, epitaxy.

In some embodiments, the second type semiconductor layer120is made of, for example, p-doped GaN or p-doped AlGaInP. The thickness of the second type semiconductor layer120is in a range from 50 nm to 20 μm. The second type semiconductor layer120is formed by, for example, epitaxy.

In some embodiments, the active layer150is made of, for example, heterostructure or quantum well structure. The thickness of the active layer150is in a range from 50 nm to 5 μm. The active layer150is formed by, for example, epitaxy.

The first electrodes140aand the second electrodes140bare made of a conductive material, such as metal or a transparent conductive material, e.g. indium tin oxide (ITO). The first electrodes140aand the second electrodes140bcan be formed by, for example, physical vapor deposition (PVD) or chemical vapor deposition (CVD).

In some embodiments, the active layer150can be omitted. In the case that the active layer150is omitted, the second type semiconductor layer120is disposed on the first type semiconductor layer110.

In some embodiments, the dielectric layer130is made of a dielectric material, such as silicon nitride or silicon dioxide. The thickness of the dielectric layer130is in a range from 10 nm to 5 μm. The dielectric layer130is formed by, for example, physical vapor deposition (PVD).

In addition, a method for manufacturing the micro-LED100is provided. With reference made toFIG. 1, the method for manufacturing the micro-LED100includes following steps:

Step (1): forming a second type semiconductor layer120on or above a first type semiconductor layer110;

Step (2): forming a dielectric layer130on the second type semiconductor layer120;

Step (3): forming a first opening O1and a second opening O2in the dielectric layer130; and

Step (4): forming a first electrode140aand a second electrode140bpartially on the dielectric layer130and electrically coupled with the second type semiconductor layer120respectively through the first opening O1and the second opening O2, in which the first electrode140aand the second electrode140bare separated from each other.

Furthermore, the first electrode140aand the second electrode140bare formed by such as, but not limited to, photolithography, screen printing, or inkjet printing, and the method further includes forming an active layer150between the first semiconductor layer110and the second type semiconductor layer120.

FIG. 5is a cross-sectional view of a micro-LED according to the second embodiment of this invention, andFIG. 6is a plan view of the micro-LED ofFIG. 5, wherein the electrodes are removed. The difference between this embodiment and the first embodiment is that the number of the openings of the dielectric layer130is added from two to three.

In addition to the first opening O1and the second opening O2, the dielectric layer130has a third opening O3. Therefore, the micro-LED100further includes a third electrode140c, and the third electrode140cis disposed on the dielectric layer130and is electrically coupled with a exposed part of the second type semiconductor layer120through the third opening O3. Similarly, the first electrode140a, the second electrode140b, and the third electrode140care separated from each other.

Other details regarding the micro-LED100ofFIG. 5andFIG. 6are similar to the micro-LED100ofFIG. 1andFIG. 3and therefore are not repeated here to avoid duplicity.

In some embodiments, the range of the brightness of the micro-LED100is broadened by adding the numbers of the openings and the electrodes. In this embodiment, the first opening O1has an area A1, the second opening O2has an area A2, the third opening O3has an area A3, and A1<A2<A3. Therefore, In this configuration, when the micro-LED100is operated within the linear current density range from J1to J2(seeFIG. 4), the openings allow current flowing through the micro-LED100to be controlled within a continuous current range from A1*J1to (A1+A2+A3)*J2.

In addition, the openings in this embodiment have the different areas (A1<A2<A3), but are not limited thereto. In some embodiments, a relationship between them is A1≦A2≦A3. That is, the areas A1, A2, and A3may be arranged in various ways. For example, all the openings of the dielectric layer130may have the same area (A1=A2=A3) or have different areas (A1<A2<A3). Furthermore, at least one portion of the openings of the dielectric layer130having the same area (A1=A2<A3) is also allowable.

According to the aforementioned configuration, the dielectric layer130has three openings, but is not limited thereto. In some embodiments, the number of the openings of the dielectric layer130is n, in which the openings respectively have areas A1to An in order from smallest to largest. When the micro-LED100is operated within the linear current density range from J1to J2, the openings are dimensioned to allow the current flowing through the micro-LED100to be controlled within a continuous current range from A1*J1to (A1+A2+ . . . An)*J2. In addition, the number n is in a range from 2 to 1000 in some embodiments. With the various numbers of the openings, the brightness of the micro-LED100can be varied further, and the brightness range also can be broaden.

Furthermore, the electrodes of the micro-LED100may be divided into a first group and a second group, and then controlling the potential difference between the electrodes and the first type semiconductor layer110is applied further. For example, assuming the numbers of the openings of the dielectric layer130and electrodes corresponding to the openings are six hundred, in which the three hundred electrodes belong to the first group and the other three hundred electrodes belong to the second group. Then, the electric potential of the first group of the electrodes is controlled to be V1, the electric potential of the second group of the electrodes is controlled to be V2, the electric potential of the first type semiconductor layer110is V3, and V1≠V2=V3(for example, V1>V2=V3), such that the current flows into the micro-LED100through the first group of the electrodes.

FIG. 7is a plan view of a micro-LED according to the third embodiment of this invention, wherein the electrodes are removed. The difference between this embodiment and the second embodiment is that the first opening O1is octagonal with an area A1, the second opening O2is square with an area A2, and the third opening O3is rectangular with an area A3, in which the areas A2and A3are four times and thirty times bigger than the area A1, respectively. This embodiment demonstrate an arrangement of the openings with coefficient between their areas.

Other details regarding the micro-LED100ofFIG. 7are similar to the micro-LED100ofFIG. 1and therefore are not repeated here to avoid duplicity.

Furthermore, the micro-LED100is operated within the linear current density range from J1to J2(seeFIG. 4), in which the current density J2is ten times greater than the current density J1. For making the description succinct, the sizes of the area A1, A2, and A3are marked as A,4A, and30A, respectively, and the current density J1and J2are marked as J and10J.

Therefore, for the first opening O1, current flowing into the micro-LED100through the first opening O1is in a range from A*J to A*10J. For the second opening O2, current flowing into the micro-LED100through the second opening O2is in a range from4A*J to4A*10J. For the third opening O3, current flowing into the micro-LED100through the third opening O3is in a range from30A*J to30A*10J.

Moreover, since the brightness of light outputted through the first opening O1is proportional to the current flowing through the first opening O1, the brightness of the first opening O1is marked in a range from B to10B. Similarly, the brightness of the second opening O2is marked in a range from4B to40B, and the brightness of the third opening O3is marked in a range from30B to300B.

Since the electrodes are controlled individually, the lowest brightness of the micro-LED100is B when the current only flows through the first opening O1with the low current density J1. Relatively, the highest brightness of the micro-LED100is occurred when the current simultaneously flows through all the openings, including the first opening O1, the second opening O2, and the third opening O3with the high current density J2, and hence the highest brightness of the micro-LED100superposed by the respective highest brightness of the first opening O1, the second opening O2, and the third opening O3is350B (10B+40B+300B). Therefore, the brightness of the micro-LED100is in a range from B to350B.

In addition to controlling the current density, the plural openings of the micro-LED100allow the brightness range to be broader such that the highest bright is extended thirty-five times from10B (only the first opening O1) to350B. However, the exact brightness of the micro-LED100is determined by the current, which is the product of the total area of the openings and the current density, and the range from B to350B is a proportional relationship.

FIG. 8is a dynamic-brightness range of the micro-LED ofFIG. 7. As shown inFIG. 7andFIG. 8, the proportional relationship of the brightness of the first opening O1, the second opening O2, and the third opening O3is converted to logarithmic scale.

For the first opening O1, the brightness is converted to in a range from log 1 to log 10 (0 to 1), and the range is marked as the range A inFIG. 8. For the second opening O2, the brightness is converted to in a range from log 4 to log 40 (approximately 0.6 to 1.6), and the range is marked as the range B inFIG. 8. For the third opening O3, the brightness is converted to in a range from log 30 to log 300 (approximately 1.48 to 2.48), and the range is marked as the range C inFIG. 8. In addition, the brightness of the micro-LED100is converted to in a range from log 1 to log 350 (approximately 0 to 2.544), and the range is marked as the range D inFIG. 8.

Similarly, since the adjacent ranges, range A and range B or range B and range C, are overlapped, the range D superposed by the brightness of the first opening O1, the second opening O2, and the third opening O3is continuous.

In simple terms, the brightness corresponding to range D is determined by the number of the openings with current flowing through and the current density in the range from J1to J2. In some embodiments, the lowest current density is in a range form 0.1 A/cm2to 1 A/cm2and the highest current density is in a range from 10 A/cm2to 100 A/cm2. However, a person having ordinary skill in the art may choose a proper current density range. For the current density range, setting the lowest current density may allow the micro-LED100to be operated within the linear current density range, and setting the highest current density may prevent the micro-LED100from the current being too strong. Moreover, too strong current may cause lifetime and efficiency of the micro-LED100decrease.

In summary, since the electrodes of the micro-LED100are separated from each other, the number of the openings with current flowing through is decided by the number of the electrodes applied with electric potential that is different from the first semiconductor layer (seeFIG. 1). Therefore, current in amperes of the micro-LED100can be calculated by determining the product of the current density and the total area of the openings with current flowing, and hence the current flowing through the micro-LED100is controllable and variable.

That is, the micro-LED100is allowed to emit light with the brightness that is proportional to the current flowing through the micro-LED100such that the brightness with the range D of the micro-LED100is also controllable and variable, and hence the range D is a dynamic-brightness range. For example, assuming the area A is 25 μm2, the area B is 100 μm2, the area C is 750 μm2, and the current density is in a range from 1 A/cm2to 10 A/cm2, the current flowing through the micro-LED100is in a range from the lowest current 25*10−6A to the highest current 8750*10−6A, and the brightness of the micro-LED100that is controllable and variable is proportional to this range.

FIG. 9is a plan view of a plurality of micro-LEDs according to the fourth embodiment of this invention, wherein the electrodes are removed. As shown inFIG. 9, the dielectric layer130has a plurality of openings O therein. The number of the openings O is in a range from 2 to 1000. The openings O are arranged in an array, and all the openings O have the same shape. More specifically, the openings O of the dielectric layer130viewed in a direction normal to the dielectric layer130are circular, square, rectangular, octagonal, or polygonal.

On the other hand, the micro-LED100viewed in a direction normal to the dielectric layer130is circular, square, rectangular, octagonal, or polygonal, in which the shape of the micro-LED100viewed in a direction normal to the dielectric layer130is independent of the shape of the openings O. Therefore, the micro-LED100and the openings O may have the same shape or the different shapes.

Other details regarding the micro-LED100ofFIG. 9are similar to the micro-LED100ofFIG. 1and therefore are not repeated here to avoid duplicity.

FIG. 10is a plan view of a plurality of micro-LEDs according to the fifth embodiment of this invention, wherein the electrodes are removed. The difference between the micro-LED100ofFIG. 10and the micro-LED100ofFIG. 9is that all the openings O of the dielectric layer130have different shapes. Similarly, the shape of the micro-LED100is independent of the shape of the openings O.

Other details regarding the micro-LED100ofFIG. 10are similar to the micro-LED100ofFIG. 1and therefore are not repeated here to avoid duplicity.

FIG. 11is a plan view of a plurality of micro-LEDs according to the sixth embodiment of this invention, wherein the electrodes are removed. The difference between the micro-LED100ofFIG. 11and the micro-LED100ofFIG. 9is that at least one portion of the openings O of the dielectric layer130have the same shape. For example, the openings O are divided three parts, one portion of the openings is circular, another portion of the openings is square, and the other portion is octagonal. Similarly, the shape of the micro-LED100is independent of the shape of the openings O.

Any element in a claim that does not explicitly state “means for” performing a specified function, or “step for” performing a specific function, is not to be interpreted as a “means” or “step” clause as specified in 35 U.S.C. §112, 6th paragraph. In particular, the use of “step of” in the claims is not intended to invoke the provisions of 35 U.S.C. §112, 6th paragraph.