Gallium nitride-based compound semiconductor light-emitting device
It is an object of the present invention to provide a gallium nitride-based compound semiconductor light-emitting device that is excellent in light output efficiency and needs only a low driving voltage (Vf). The inventive gallium nitride-based compound semiconductor light-emitting device includes an n-type semiconductor layer, a light-emitting layer and a p-type semiconductor layer formed of a gallium nitride-based compound semiconductor and stacked in this order on a substrate, and positive and negative electrodes so arranged as to be in contact with the p-type semiconductor layer and the n-type semiconductor layer, respectively, wherein a region in which a p-type impurity and hydrogen atoms are co-present exists in the p-type semiconductor layer in contact with the positive electrode, and at least a portion, which is in contact with the p-type semiconductor layer, of the positive electrode, is formed of an n-type electro-conductive light transmitting material.
1. A gallium nitride-based compound semiconductor light-emitting device including:
an n-type semiconductor layer,
a light-emitting layer, and
a p-type semiconductor layer formed of a gallium nitride-based compound semiconductor and stacked in this order on a substrate, and
positive and negative electrodes so arranged as to be in contact with the p-type semiconductor layer and the n-type semiconductor layer, respectively, wherein a region in which a p-type impurity and hydrogen atoms are co-present exists in the p-type semiconductor layer in contact with the positive electrode, and at least a portion, which is in contact with the p-type semiconductor layer, of the positive electrode is formed of an n-type electro-conductive light transmitting material.
2. The gallium nitride-based compound semiconductor light-emitting device according to claim 1 , wherein a hydrogen atom concentration in the region in which the p-type impurity and the hydrogen atom are co-present is 1/10 to 2/1 with respect to a p-type impurity concentration.
3. The gallium nitride-based compound semiconductor light-emitting device according to claim 2 , wherein the hydrogen atom concentration in the region in which the p-type impurity and the hydrogen atom are co-present is 1/5 to 1.5/1 with respect to the p-type impurity concentration.
4. The gallium nitride-based compound semiconductor light- emitting device according to claim 3 , wherein the hydrogen atom concentration and the p-type impurity concentration are substantially equal to each other in the region in which the p-type impurity and the hydrogen atoms are co-present.
5. The gallium nitride-based compound semiconductor light-emitting device according to claim 1 , wherein a thickness of the region in which the p-type impurity and the hydrogen atoms are co-present is at least 40% of a thickness of an entire p-type semiconductor layer in contact with the positive electrode.
6. The gallium nitride-based compound semiconductor light-emitting device according to claim 5 , wherein the thickness of the region in which the p-type impurity and the hydrogen atoms are co-present is at least 70% of the thickness of the entire p-type semiconductor layer in contact with the positive electrode.
7. The gallium nitride-based compound semiconductor light-emitting device according to claim 1 , wherein the n-type electro-conductive light transmitting material is at least one kind of material selected from the group consisting of ITO, TiO 2 , ZnO, Bi 2 O 3 , MgO, ZnAlO, ZnS and Sn 0 2 .
8. The gallium nitride-based compound semiconductor light-emitting device according to claim 7 , wherein the n-type electro-conductive light-emitting material contains at least ITO.
9. The gallium nitride-based compound semiconductor light- emitting device according to claim 1 , wherein a thickness of the portion formed of the n-type electro-conductive light transmitting material of the positive electrode is 35 nm to 10 μm.
10. The gallium nitride-based compound semiconductor light-emitting device according to claim 9 , wherein the thickness of the portion formed of the n-type electro-conductive light transmitting material of the positive electrode is 100 nm to 1 μm.
11. A lamp comprising a gallium nitride-based compound semiconductor light-emitting device according to claim 1 .