Abstract The invention relates to an avalanche photodetector having a charge-multiplication region which is spatially separated from the detector surface. This photodetector includes a light-absorptive region, an active region overlying the absorptive region and having a central zone which has a greater concentration of conductivity modifiers than the remainder of the active region. A cap region overlies the first region, has the opposite conductivity type and extends a greater distance in the lateral direction than the central zone. The invention is also a method of forming this detector comprising the steps of forming a first region of the active region, embedding an excess concentration of conductivity modifiers into a portion thereof and then forming a second region of the active region on the first region. A cap region of opposite conductivity type is then formed over the active region. The cap region has a greater lateral extent than the portion containing the excess concentration of conductivity modifiers.
An avalanche photodetector comprising a semiconductor body, said body including: a light absorptive region having a major surface; an active region overlying said major surface and having a central zone therein; a cap region overlying said active region over said central zone, said cap region having a lateral extent greater than that of said central zone; and means for electrically contacting said semiconductor body; said absorptive and active regions and said central zone having one conductivity type and said cap region having the opposite conductivity type; said central zone having a greater concentration of first type conductivity modifiers than the remainder of said active region and being spaced apart from said absorptive and cap regions within said active region.
Claim 2
Dependent Claim
119 words
An avalanche photodetector comprising a semiconductor body, said body including: a light absorptive region having a major surface; an active region overlying said major surface and having a central zone therein; a cap region overlying said active region over said central zone, said cap region having a lateral extent greater than that of said central zone; and means for electrically contacting said semiconductor body; said absorptive and active regions and said central zone having one conductivity type and said cap region having the opposite conductivity type; said central zone having a greater concentration of first type conductivity modifiers than the remainder of said active region and being spaced apart from said absorptive and cap regions within said active region.
Claim 3
Dependent Claim
26 words
The photodetector of claim 1, wherein the areal concentration of conductivity modifiers in said central zone is between about 2 and 4×10 12 /cm 2 .
Claim 4
Dependent Claim
17 words
The photodetector of claim 2, wherein said central zone is between about 0.1 and 0.3 micrometers thick.
Claim 5
Dependent Claim
19 words
The photodetector of claim 3, further comprising a substrate with said absorptive region overlying a surface of said substrate.
Claim 6
Dependent Claim
26 words
The photodetector of claim 4, further comprising a buffer layer overlying said surface of said substrate and said absorptive overlying a surface of said buffer layer.
Claim 7
Dependent Claim
62 words
The photodetector of claim 3, wherein said substrate is composed of N-type InP, said absorptive region is composed of a ν-type material selected from a group consisting of In 0 .57 Ga 0 .43 As and In x Ga 1-x As y P 1-y alloys, said active region is composed of ν-type InP and said cap region is composed of P-type InP.