Electrode contact structure of light-emitting diode with improved roughness

#The present invention relates to a light-emitting diode (LED), and particularly to an electrode contact structure of an LED.

#A light-emitting diode (LED), offering advantages of being compact in size and power-saving, prevails in applications including illuminations, traffic lights and commercial signs. An LED is principally formed by a semiconductor material with multiple stacked epitaxial layers. For example, a blue-light LED is mainly consisted of gallium nitride-based (GaN-based) epitaxial thin films.

#Referring to FIGS. 1A and 1B, a conventional vertical LED includes a sandwich structure formed by an N-type semiconductor layer 1, a light-emitting layer 2 and a P-type semiconductor layer 3. Below the P-type semiconductor layer 3, a mirror layer 4, a buffer layer 5, a binding layer 6, a silicon substrate 7 and a P-type electrode 8 are formed in sequence. A surface of the N-type semiconductor layer 1 is processed by a roughening treatment for increasing light extraction. An N-type electrode 9 is further provided. By applying a voltage to the N-type electrode 9 and the P-type electrode 8, the N-type semiconductor layer 1 is enabled to provide electrons and the P-type semiconductor layer 3 is enabled to provide holes. Light is produced by the electrons and holes combining at the light-emitting layer 2.

#FIG. 1A is a schematic diagram of a conventional LED.

#FIG. 1B depicts voids in a conventional LED.

#FIG. 2 is a schematic diagram of an LED structure according to one embodiment of the present invention.

#In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that the embodiments are for exemplary examples for illustrating the prevent invention and are not to be construed as limiting the present invention thereto.

#FIG. 2 shows a schematic diagram of an LED electrode structure for an LED according to one embodiment of the present invention. An LED 100 comprises a plurality of N-type electrodes 10, an N-type semiconductor layer 20, a light-emitting layer 30, a P-type semiconductor layer 40, a mirror layer 50, a buffer layer 60, a binding layer 70, a permanent substrate 80 and a P-type electrode 90 that are stacked in sequence. An irregular surface 201 is formed on the N-type semiconductor layer 20.

#The N-type semiconductor layer 20 integrally forms a plurality of contact platforms 202. The contact platforms 202 are formed and distributed on the N-type semiconductor layer 20 in a patterned arrangement. On the N-type semiconductor layer 20, the irregular surface 201 is formed at areas without the contact platforms 202. The N-type electrodes 10 are respectively formed on the contact platforms 202. The contact platforms have roughness between 0.01 μm and 0.1 μm, and surfaces of the N-type electrodes 10 are also formed with roughness between 0.01 μm and 0.1 μm. Further, the irregular surface 201 has roughness between 0.5 μm and 1 μm.