Light emitting device with pillar structure having hollow structure

1. A light emitting device, comprising: a substrate; a first semiconductor layer disposed on a surface of said substrate; an active layer disposed on a first portion surface of said first semiconductor layer; a second semiconductor layer disposed on said active layer; a transparent conductive layer disposed on said second semiconductor layer; and a plurality of pillar structures disposed on a second portion surface of said first semiconductor layer, said plurality of pillar structures having a hollow structure therein, and said plurality of pillar structures being separated from each other,

wherein each said plurality of pillar structures from top to bottom comprises said second semiconductor layer, said active layer, and said first semiconductor layer,

wherein the depth of said hollow structure of each said plurality of pillar structures respectively extends down from said second semiconductor layer until an arbitrary depth of said second semiconductor layer, from said second semiconductor layer until an exposed surface of said active layer, from said second semiconductor layer until an arbitrary depth of said active layer, from said second semiconductor layer through said active layer until an exposed surface of said first semiconductor layer, from said second semiconductor layer through said active layer until an arbitrary depth of said first semiconductor layer, and from said second semiconductor layer through said active layer and extended down until a bottom portion of said first semiconductor layer.

2. The light emitting device according to claim 1 , wherein each said plurality of pillar structures from top to bottom comprises said active layer and said first semiconductor layer, and the depth of said hollow structure of each said plurality of pillar structures is down from said active layer to an arbitrary depth of said active layer, from said active layer to an exposed surface of said first semiconductor layer, from said active layer to an arbitrary depth of said first semiconductor layer, or from said active layer through said first semiconductor layer to an exposed surface of said substrate.

3. The light emitting device according to claim 1 , wherein each said plurality of pillar structures comprises said first semiconductor layer, and the depth of said hollow structure of each said plurality of pillar structures is down from said first semiconductor layer to an arbitrary depth of said first semiconductor layer, or from said first semiconductor layer to an exposed surface of said substrate.

4. The light emitting device according to claim 1 , wherein an outer surface and an inner surface of said plurality of pillar structures with said hollow structure is a rough surface.

5. The light emitting device according to claim 1 , wherein a portion surface of said first semiconductor layer, a sidewall of said active layer, and a sidewall of said second semiconductor layer is a rough surface.

6. The light emitting device according to claim 1 , further comprising a first electrode disposed on said second portion surface of said first semiconductor layer.

7. The light emitting device according to claim 1 , wherein said transparent conductive layer exposed a portion surface of said second semiconductor layer.

8. The light emitting device according to claim 7 , further comprising a second electrode disposed on an exposed surface of said second semiconductor layer, and connected with said transparent conductive layer.

9. The light emitting device according to claim 1 , further comprising a second electrode disposed on said transparent conductive layer.