Light-emitting diode having moisture-proof characteristics and high output power

• US 6,043,509 A
• Filed: 12/01/1998
• Issued: 03/28/2000
• Est. Priority Date: 12/13/1996
• Status: Expired due to Fees

• Current Assignee: Hitachi Cable Limited (Proterial Ltd.)
• Original Assignee: Hitachi Cable Limited (Proterial Ltd.)
• Inventors: Toyoshima, Toshiya, Kurihara, Tooru, Noguchi, Masahiro, Mizuniwa, Seiji
• Primary Examiner(s): Tran, Minh Loan
• Application Number:
  US09/201,835
• Time in Patent Office: 483 Days
• Field of Search: 257/12, 257/13, 257/94, 257/96, 257/103, 257/79
• US Class Current: 257/13
• CPC Class Codes: H01L 33/0062 for devices with an active region comprising only III-V compounds
• CPC Class Codes: H01L 33/30 containing only elements of Group III and Group V of the Periodic Table
• CPC Class Codes: H01L 33/305 characterised by the doping materials

Abstract

A Light-emitting diode having improved moisture resistance characteristics comprises a p-type gallium arsenide substrate and four epitaxial layers of Al_x Ga_1-x As (22, 23, 24 and 25). These epitaxial layers comprises an intervening layer (22) of p-type Al_x1 Ga_1-x1 As, a cladding layer (23) of p-type Al_x2 Ga_1-x2 As, an active layer (24) of Al_x3 Ga_1-x3 As, and a window layer (25) of Al_x4 Ga_1-x4 As so as to form a double-hetero structure, where x1, x2, x3 and x4 represent mixed crystal ratios of aluminum to arsenic of the layers, respectively, and meet the condition that:

x2≧x4>x1≧x3 (0≦x1, x2, x3, x4≦1).

Claims

1. A light-emitting diode having a plurality of hetero-junctions of aluminum gallium arsenide, comprising:

a substrate of p-type gallium arsenide;

an intervening layer of p-type Al_x1 Ga_1-x As formed on said substrate;

a cladding layer of p-type Al_x2 Ga_1-x2 As formed on said intervening layer;

an active layer of p-type Al_x3 Ga_1-x3 As formed an said cladding layer; and

a window layer of n-type Al_x4 Ga_1-x4 As formed on said active layer;

wherein x1, x2, x3 and x4 represent mixed crystal ratios of aluminum to arsenic of said layers, respectively, and meet the condition in that;

space="preserve" listing-type="equation">x2≧

x4>

x1≧

x3 (0≦

x1, x2, x3, x4≦

1).

2. A light-emitting diode, according to claim 1, wherein:

a thickness of said cladding layer is 0.05-10 micro meters.

3. A light-emitting diode having a plurality of hetero-junctions of aluminum gallium arsenide layers, each of said aluminum gallium arsenide being formed by epitaxial growth, comprising:

a substrate of p-type gallium arsenide;

an intervening layer of aluminum gallium arsenide formed on said substrate;

a cladding layer of aluminum gallium arsenide formed on said intervening layer;

an active layer of aluminum gallium arsenide formed on said cladding layer; and

a window layer of aluminum gallium arsenide formed on said active layer;

wherein said intervening, cladding and active layers are doped with at least one p-type dopant, respectively, and said window layer is doped with at least one n-type dopant, said at least one p-type dopant in said cladding layer being thermally diffused from said intervening layer by subsequent epitaxial growths of said active layer and said window layer so as to invert the initial type of conduction of said cladding layer.

4. A light-emitting diode, according to claim 3, wherein:

a thickness of said cladding layer is 0.05-10 micro meters.