Method for testing light-emitting devices

1. A method for testing LEDs, comprising:

Step 1: providing a wafer comprising a plurality of LEDs and selecting N LEDs from the plurality of LEDs to form an LED group;

Step 2: selecting n LEDs from the LED group, where 1<n<N, and testing the n LEDs at a time to obtain a subgroup optical parameter of the LED group;

Step 3: performing the Step 2 on the N LEDs repeatedly and alternately for another n LEDs in the LED group to obtain a plurality of the subgroup optical parameters; and

Step 4: obtaining an optical parameter of each of the LEDs in the LED group from the plurality of the subgroup optical parameters, wherein each of the subgroup optical parameters comprises a sum or a superimposition of optical parameters of the n LEDs which are selected and tested at the time.

2. The method according to claim 1 , wherein the optical parameter comprises a brightness, an emission spectrum, or an emission wavelength of the LED.

3. The method according to claim 2 , wherein the subgroup optical parameter comprises a sum of the brightness, a superimposed emission spectrum or a superimposed emission wavelength of the n LEDs which are selected and tested at the time.

4. The method according to claim 3 , wherein the Step 4 comprises:

setting the optical parameter of each of the LEDs as an unknown optical parameter, and the N LEDs comprises N unknown optical parameters;

the N unknown optical parameters and the plurality of subgroup optical parameters composing a plurality of equations; and

calculating the N unknown optical parameters from the plurality of equations.

5. The method according to claim 1 , further comprising using probe sets to contact the N LEDs and wherein each of the N LEDs comprises a first electrode and a second electrode; and

wherein the Step 2 comprises:

using n probe sets to respectively contact the n LEDs at a time, wherein each of the n probe sets comprises a first probe and a second probe, and the first probe and the second probe of each of the n probe sets respectively contact the first electrodes and the second electrodes of each of the n LEDs;

inputting voltage or current to the n probe sets; and

testing the n LEDs to obtain the subgroup optical parameter.

6. The method according to claim 1 , further comprising using probe sets to contact the N LEDs and wherein each of the N LEDs comprises a first electrode and a second electrode; and

wherein the Step 2 comprises:

using N probe sets to respectively contact the N LEDs at a time, wherein each of the N probe sets comprises a first probe and a second probe, and the first probe and the second probe of each of the N probe sets respectively contact the first electrode and the second electrode of each of the N LEDs;

inputting voltage or current to the n probe sets among the N probe sets and not inputting the voltage or the current to the probe set among the N probe sets other than the n probe sets; and

testing the n LEDs to obtain the subgroup optical parameter.

7. The method according to claim 1 , wherein each of the N LEDs comprises a first electrode and a second electrode, and a distance between the first electrode and the second electrode is less than 100 μm.

8. The method according to claim 1 , wherein each of the N LEDs comprises diagonal length in a range of 100 μm to 300 μm.

9. The method according to claim 1 , wherein the plurality of LEDs is arranged in an array with a plurality of rows and a plurality of columns, and the N LEDs are arranged in the same row, in the same column or in a sub-array of the array.

10. The method according to claim 1 , wherein the Step 3 comprises:

performing the Step 2 on the N LEDs repeatedly and alternately until any other n LEDs in the LED group have been tested to obtain the plurality of the subgroup optical parameters.

11. The method according to claim 1 , wherein each of the LEDs comprises a substrate and a semiconductor stack on the substrate.

12. The method according to claim 11 , wherein the plurality of LEDs is fixed to a carrier.

13. The method according to claim 11 , further comprising an adhesive layer between the substrate and the semiconductor stack.

14. The method according to claim 1 , wherein the plurality of LEDs comprises a first LED other than the N LEDs and the N LEDs are discontinuously arranged in the wafer with the first LED disposed therebetween.

15. The method according to claim 14 , wherein an average of the optical parameters of the N LEDs in the LED group is regarded as an optical parameter of the first LED.

16. The method according to claim 14 , wherein the first LED is adjacent to one of the LEDs among the N LEDs, and the optical parameter of the one of the LEDs is regarded as an optical parameter of the first LED.

17. The method according to claim 1 , further comprising selecting and designated other N LEDs in the plurality of LEDs as a different LED group; and

performing the Step 2 to the Step 4 on the different LED group.