Light generating semiconductor device and method of making the same

1. A method of making a semiconductor light generating device, the method comprising the steps of:

forming a GaN-based semiconductor portion on a Al X Ga 1-X N (0 ≦×≦1) substrate, the GaN-based semiconductor portion including a light generating film, the light generating film having a threading dislocation density smaller than 1×10 7 cm −2 ;

forming an electrode film on the GaN-based semiconductor portion;

bonding a conductive substrate to a surface of the electrode film using a conductive adhesive; and

after bonding the conductive substrate, separating one of the Al X Ga 1-X N substrate and the GaN-based semiconductor portion from the other,

wherein the light generating film is only made of material having a bandgap energy greater than material of the substrate.

2. The method according to claim 1 , wherein the conductive substrate is made of metal.

3. The method according to claim 1 , wherein the Al X Ga 1-X N substrate is a GaN substrate.

4. The method according to claim 3 , the method further comprising the step of:

prior to forming the GaN-based semiconductor portion, forming a sacrificial film on the GaN substrate, the sacrificial film being made of a first material, the first material having a band gap smaller than the material of the substrate,

wherein separating one of the GaN substrate and the GaN-based semiconductor film from the other includes a step of irradiating the sacrificial film with light to perform lift-off of one of the GaN substrate and the GaN-based semiconductor portion from the other, the light including a wavelength component corresponding to a energy smaller than a bandgap energy of GaN semiconductor.

5. The method according to claim 3 , the method further comprising the steps of:

reconditioning the separated GaN substrate for reuse; and

performing the following steps using the reconditioned GaN substrate:

forming a GaN-based semiconductor portion on the reconditioned GaN substrate, the GaN-based semiconductor portion including a light generating film;

forming an electrode film on the GaN-based semiconductor portion;

bonding a conductive substrate to a surface of the electrode film; and

after bonding the conductive substrate, separating one of the reconditioned GaN substrate and the GaN-based semiconductor portion from the other.

6. The method according to claim 1 , wherein the Al X Ga 1-X N substrate (0 ≦×<1) is an Al X Ga 1-X N substrate (0 <×≦1).

7. The method according to claim 6 , the method further comprising the step of:

prior to forming the GaN-based semiconductor portion, forming a sacrificial film on the Al X Ga 1-X N substrate, the sacrificial layer being made of a first material, the first material having a baudgap smaller than material of the Al X Ga 1-X N substrate,

wherein separating one of the Al X Ga 1-X N substrate and the GaN-based semiconductor portion from the other includes a step of irradiating the sacrificial film with light to perform lift-off of one of the Al X Ga 1-X N substrate and the GaN-based semiconductor portion from the other, the light including a wavelength component corresponding to a energy smaller than a bandgap energy of material of the substrate.

8. The method according to claim 6 , the method further comprising the steps of:

reconditioning the separated Al X Ga 1-X N substrate for reuse; and

performing the following steps using the reconditioned Al X Ga 1-X N substrate:

forming a GaN-based semiconductor portion on the reconditioned Al X Ga 1-X N substrate, the GaN-based semiconductor portion including a light generating film;

forming an electrode film on the GaN-based semiconductor portion;

bonding a conductive substrate to a surface of the electrode film; and

after bonding the conductive substrate, separating one of the reconditioned Al X Ga 1-X N substrate and the GaN-based semiconductor portion from the other.

9. The method according to claim 1 , wherein the light generating film is made of nitride compound semiconductor containing aluminum.

10. The method according to claim 1 , wherein the conductive substrate is made of one of Cu-W alloy and Fe-Ni alloy.

11. The method according to claim 1 , wherein the conductive adhesive contains one of Au-Sn solder and Pb-Ni solder.

12. The method according to claim 1 , wherein the electrode film is made of material having a reflectivity greater than the conductive substrate at a peak wavelength of light from the light generating layer.

13. The method according to claim 1 , wherein the light generating film is made of AlGaN.

14. A method of making a semiconductor light generating device, the method comprising the steps of:

forming a sacrificial film on a GaN substrate, the sacrificial film being made of a first material, the first material having a band gap smaller than the material of the substrate;

forming a GaN-based semiconductor portion on the GaN substrate, the GaN-based semiconductor portion including a light generating film;

forming an electrode film on the GaN-based semiconductor portion;

bonding a conductive substrate to a surface of the electrode film using a conductive adhesive; and

after bonding the conductive substrate, separating one of the GaN substrate and the GaN-based semiconductor portion from the other,

wherein the sacrificial film is made of nitride compound semiconductor containing indium and

wherein separating one of the GaN substrate and the GaN-based semiconductor film from the other includes a step of irradiating the sacrificial film with light to perform lift-off of one of the GaN substrate and the GaN-based semiconductor portion from the other, the light including a wavelength component corresponding to a energy smaller than a bandgap energy of GaN semiconductor.

15. A method of making a semiconductor light generating device, the method comprising the steps of:

forming a sacrificial film on a Al X Ga 1-X N substrate (0 <×≦1), the sacrificial layer being made of a first material, the first material having a bandgap smaller than material of the Al X Ga 1-X N substrate;

forming a GaN-based semiconductor portion on the Al X Ga 1-X N substrate, the GaN-based semiconductor portion including a light generating film;

forming an electrode film on the GaN-based semiconductor portion;

bonding a conductive substrate to a surface of the electrode film using a conductive adhesive; and

after bonding the conductive substrate, separating one of the Al X Ga 1-X N substrate and the GaN-based semiconductor portion from the other,

wherein the sacrificial layer is made of nitride compound semiconductor containing indium and

wherein separating one of the Al X Ga 1-X N substrate and the GaN-based semiconductor portion from the other includes a step of irradiating the sacrificial film with light to perform lift-off of one of the Al X Ga 1-X N substrate and the GaN-based semiconductor portion from the other, the light including a wavelength component corresponding to a energy smaller than a bandgap energy of material of the substrate.