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Semiconductor light-emitting device and method of fabricating the same

Semiconductor light-emitting device and method of fabricating the same description/claims

This application is a Divisional of co-pending application Ser. No. 11/798,873 filed on Aug. 25, 2008, and for which priority is claimed under 35 U.S.C. § 120; and this application claims priority of Application No. 095127869 filed in Taiwan R.O.C. on Jul. 28, 2006 under 35 U.S.C. § 119; the entire contents of all are hereby incorporated by reference.

1. Field of the Invention

The invention relates to a semiconductor light-emitting device, and more particularly, to one with II-V group (or II-IV-V group) compound contact layer. With respect to the technology background of the invention, please refer to the following references: [1] K. Kuriyama, Yukimi Takahashi, F. Sunohara. Optical band gap of Zn3N2 films. PHYSICAL REVIEW B 1993; 48(4):2781-2782; [2] B. Chelluri, T. Y. Chang, A. Ourmazd, A. H. Dayem, J. L. Zyskind, A. Srivastava. Molecular beam epitaxial growth of the II-V semiconductor compound Zn3As2. Appi. Phys. Lett. 1986; 49(24):1665-1667; [3] M. Sieberer, J. Redinger, S. K melevskyi, P. Mohn. Ferromagnetism in tetrahedrally coordinated compounds of I/H-V elements: Ab initio calculations. PHYSICAL REVIEW B 2006; 73(024404): 1-9; and [4] C M Fang, R A de Groot, R J Bruls, H T Hintzen, G de With. Ab initio band structure calculations of Mg3N2 and MgSiN2. J. Phys. 1999; Condens. Matter 11:4833-4842.

2. Description of the Prior Art

Light-emitting diodes can be applied to various kinds of equipments, such as 1 optical display equipments, regulatory signs, telecommunication equipments, and illuminating equipments. Light-emitting diodes, distinct from the conventional light sources, are applicable to different industries.

Compared to the tungsten lamps of prior art, light-emitting diodes consume less electricity and respond more quickly. Furthermore, light-emitting diodes have better illuminating efficiency, longer life time, and smaller size; they also consume less power and do not have hazardous substances like mercury.

The radiating principle of the light-emitting diodes is that the bonding of electrons and holes in the light-emitting layer of P-type and N-type semiconductors forms photons to generate light on forward bias. Because the P-type GaN semiconductor is hard to be doped, the contact of P-type GaN semiconductor and conductive layer produces higher resistance and consequently decreases the efficiency of P-type GaN semiconductor.

Taiwanese Patent No. 459,407 provides a proposal to reduce the contact resistance between a P-type GaN semiconductor layer and a conductive layer. Referring to FIG. 1, FIG. 1 illustrates a light-emitting diode structure having an n+ type reverse tunneling layer. The light-emitting diode structure includes an insulated sapphire substrate 11, a GaN buffer layer 12, an N-type GaN contact layer 13, an N-type AlGaN constraint layer 14, an InGaN light-emitting layer 15, a P-type Al GaN constraint layer 16, a P-type GaN contact layer 17, an n+ type reverse tunneling layer 18, a transparent conductive layer 19, a first electrode 21, and a second electrode 22.

The GaN buffer layer 12 is formed on the insulated sapphire substrate 11. An N-type GaN contact layer 13 is formed on the GaN buffer layer 12 such that a partial area of the N-type GaN contact layer 13 is exposed. The first electrode 21 is formed on the exposed partial area of the N-type GaN contact layer 13. The N-type A1GaN constraint layer 14 is formed on the N-type GaN contact layer 13. The InGaN light-emitting layer 15 is formed on the N-type A1GaN constraint layer 14. The P-type

AlGaN constraint layer 16 is formed on the InGaN light-emitting layer 15. The P-type GaN contact layer 17 is formed on the P-type Al GaN constraint layer 16. The n+ type reverse tunneling layer 18 is formed on the P-type GaN contact layer 17. The transparent conductive layer 19 is formed on the n+ type reverse tunneling layer 18 such that a partial area of the n+ type reverse tunneling layer 18 is exposed. The second electrode 22 is formed on the exposed partial area of the n+ type reverse tunneling layer 18 and contacts the transparent conductive layer 19.

The light-emitting diode improves the ohmic contact between the P-type GaN contact layer 17 and the transparent conductive layer 19 by adding an n+ type reverse tunneling layer 18 between them.

However, due to a complex manufacturing process and difficult control of the n+ type reverse tunneling layer 18, the finished products of light-emitting diodes are not stable and have a higher production cost as well.

Accordingly, a scope of the invention is to provide a semiconductor light-emitting device with II-V group (or II-IV-V group) compound contact layer, capable of improving the ohmic contact between the P-type GaN contact layer and the transparent conductive layer. Moreover, the semiconductor light-emitting device with II-V group (or II-IV-V group) compound contact layer has an easier manufacturing process; it also increases the stability for production and consequently has a lower production cost.

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