1. A light emitting device comprising:
a light emitting structure including a first conductive type semiconductor layer, an active layer under the first conductive type semiconductor layer, and a second conductive type semiconductor layer under the active layer;
a first electrode on an upper side of the light emitting structure;
a second electrode on an underside of the light emitting structure;
at least one cavity penetrating the second conductive type semiconductor layer and the active layer; and
an insulating layer disposed on the at least one cavity,
wherein the second electrode comprises:
a conductive layer; and
a reflective layer disposed between the insulating layer and the conductive layer,
wherein the insulating layer and the reflective layer fully fill the cavity, and wherein the reflective layer comprises at least one protrusion in the cavity,
wherein the at least one protrusion comprises an upper portion and a lower portion having different sizes,
wherein the first electrode is vertically aligned with the at least one protrusion,
wherein a top surface of the reflective layer is higher than a top surface of the active layer in a portion vertically overlapping the first electrode, and
wherein the top surface of the reflective layer comprises a flat top surface.
2. The light emitting device of claim 1, wherein the at least one protrusion has a width which increases as it goes from the upper portion to the lower portion thereof.
3. The light emitting device of claim 1, wherein the reflective layer is disposed between the second conductive type semiconductor layer and the conductive layer.
4. The light emitting device of claim 1, wherein the insulating, layer on the at least one protrusion of the second electrode contacts the first conductive type semiconductor layer.
5. The light emitting device of claim 1, wherein the insulating layer comprises a transparent insulating layer.
6. The light emitting device of claim 1, wherein the insulating layer is disposed on a top surface and a side surface of the at least one protrusion.
7. The light emitting device of claim 6, wherein an angle between a top surface of the conductive layer and a surface of the insulating layer which is disposed on the side surface of the at least one protrusion is equal to an angle between a top surface of the active layer and the surface of the insulating layer which is disposed on the side surface of the at least one protrusion.
8. A light emitting device package comprising:
a package body;
a light emitting device of claim 1 over the package body; and
a third electrode layer formed in the package body and electrically connected to the light emitting device.
9. The light emitting device of claim 1, wherein light generated from the active layer is extracted through at least one area of an upper side of the light emitting structure.
10. The light emitting device of claim 1, wherein the reflective layer comprises a bottom portion between the conductive layer and the second conductive type semiconductor layer.
11. The light emitting device of claim 1, wherein the upper portion of the at least one protrusion comprises a flat top surface, and
a width of the at least one protrusion increases as it goes from the upper portion to the lower portion.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method for processing signals in an RF subsystem to eliminate the need for a low noise amplifier therein, the method comprising:
providing a plurality of intercoupled micromechanical devices including an input port for receiving signals and an output port; and
vibrating the micromechanical devices to initially pass a desired frequency range of unamplified signals while substantially attenuating signals outside the desired frequency range and then to convert between first and second frequencies and filter the desired frequency range of unamplified signals without the need for the low noise amplifier.
2. The method as claimed in claim 1 wherein the low noise amplifier is an RF low noise amplifier.
3. An RF receiver subsystem which eliminates the need for a low noise amplifier therein, the subsystem comprising:
an image-reject vibrating micromechanical filter including an input port for receiving signals, the filter passing a desired frequency range of the signals while substantially attenuating signals outside the desired frequency range; and
a vibrating micromechanical mixer-filter coupled to the filter having an output port, the mixer-filter being adapted to be coupled to electronics for converting and filtering the desired frequency range of signals without the need for the low noise amplifier.
4. The subsystem as claimed in claim 3 wherein the low noise amplifiers an RF low noise amplifier.
5. The subsystem as claimed in claim 3 wherein the filter is a relatively wide band filter and the mixer-filter is a narrow band mixer-filter.
6. An RF receiver subsystem which eliminates the need for a low noise amplifier, the subsystem comprising:
a vibrating micromechanical frequency range selector having an input port for receiving signals, the selector passing a desired frequency range of the signals while substantially attenuating signals outside the desired frequency range; and
a vibrating micromechanical mixer-filter coupled to the selector having an output port and being adapted to be connected to electronics for converting and filtering the desired frequency range of signals without the need for the low noise amplifier.
7. The subsystem as claimed in claim 6 wherein the low noise amplifier is an RF low noise amplifier.
8. An RF transceiver subsystem which substantially reduces the need for RF front-end power, the subsystem comprising:
a vibrating micromechanical frequency range selector having any input port for receiving signals, the selector passing a desired frequency range of the signals while substantially attenuating signals outside the desired frequency range; and
a vibrating micromechanical mixer-filter coupled to the selector having an output port, the mixer-filter being adapted to be connected to electronics for converting and filtering signals wherein the reed for RF front-end power is substantially reduced.
9. The method as claimed in claim 1 wherein the first frequency is in an RF range and the second frequency is in an IF range.
10. The subsystem as claimed in claim 3 wherein the vibrating micromechanical mixer-filter converts from an RF range to an IF range.
11. The subsystem as claimed in claim 3 wherein the image-reject vibrating micromechanical filter passes unamplified signals within the desired frequency range to the vibrating micromechanical mixer-filter.
12. The subsystem as claimed in claim 6 wherein the vibrating micromechanical mixer-filter converts from an RF range to an IF range.
13. The subsystem as claimed in claim 6 wherein the vibrating micromechanical frequency range selector passes unamplified signals within the desired frequency range to the vibrating micromechanical mixer-filter.
14. The subsystem as claimed in claim 8 wherein the vibrating micromechanical mixer-filter converts between an RF range and an IF range.
15. The subsystem as claimed in claim 8 wherein the vibrating micromechanical frequency range selector passes unamplified signals within the desired frequency range to the vibrating micromechanical mixer-filter.