Back illuminated photodiodes
First Claim
Patent Images
1. A photodetector comprising:
- an input port at an input end face for receiving light to be detected, the input port being disposed about semiconductor layers including an absorption layer for absorbing light to be detected sandwiched between first and second light transmissive epitaxial semiconductor layers, the second light transmissive eptaxial semiconductor layer being a capping layer;
a passivation layer supported by only a portion of a surface of the second light transmissive epitaxial semiconductor capping layer, said passivation layer having an opening within for accommodating a ring of a first contact layer of alloyed material that is supported by a another portion of the surface of the second light transmissive semiconductor capping layer and at least partially alloyed therewith for providing electrical contact to the epitaxial semiconductor layers via the second light transmissive semiconductor capping layer; and
, a highly reflective non-epitaxial III-V semiconductor, non-alloyed material supported in part by the first contact layer of alloyed material and supported in part by the passivation layer, said highly reflective non-epitaxial-III-V-semiconductor, non-alloyed material facing the epitaxial semiconductor layers for reflecting back light that propagated through the absorption layer for a second pass into the absorption layer;
wherein a primary electrical conduction path is formed between the first contact layer of alloyed material and the epitaxial semiconductor absorption layer.
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Abstract
A highly reflecting back illuminated diode structure allows light that has not been absorbed by a semiconductor absorbing region to be back reflected for at least a second pass into the absorbing region. The diode structure in a preferred embodiment provides a highly reflecting layer of gold to be supported in part by a conducting alloyed electrode ring contact and in part by a passivation layer of SixNy. Conveniently this structure provides a window within the contact which allows light to pass between the absorbing region and the reflecting layer of gold.
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Citations
15 Claims
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1. A photodetector comprising:
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an input port at an input end face for receiving light to be detected, the input port being disposed about semiconductor layers including an absorption layer for absorbing light to be detected sandwiched between first and second light transmissive epitaxial semiconductor layers, the second light transmissive eptaxial semiconductor layer being a capping layer;
a passivation layer supported by only a portion of a surface of the second light transmissive epitaxial semiconductor capping layer, said passivation layer having an opening within for accommodating a ring of a first contact layer of alloyed material that is supported by a another portion of the surface of the second light transmissive semiconductor capping layer and at least partially alloyed therewith for providing electrical contact to the epitaxial semiconductor layers via the second light transmissive semiconductor capping layer; and
,a highly reflective non-epitaxial III-V semiconductor, non-alloyed material supported in part by the first contact layer of alloyed material and supported in part by the passivation layer, said highly reflective non-epitaxial-III-V-semiconductor, non-alloyed material facing the epitaxial semiconductor layers for reflecting back light that propagated through the absorption layer for a second pass into the absorption layer;
wherein a primary electrical conduction path is formed between the first contact layer of alloyed material and the epitaxial semiconductor absorption layer. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A structure within a photodiode comprising:
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a semiconductor absorptive active layer for receiving and absorbing input light;
a light transmissive passivating layer forming a window over the semiconductor absorptive active layer within a contact structure, the contact structure comprising;
an electrically conductive alloyed material which forms a principal electrically conducting path to the semiconductor active layer from a contact region, said alloyed material having an opening therein surrounding the light transmissive passivating layer;
a reflector of highly reflective non-epitaxial-III-V, non-alloyed other material provided over the window and partially supported by an upper surface of the alloyed material about the window; and
a layer of metal covering at least a portion of the highly reflective other material to promote adhension between the said material and at least the passivating layer forming the window. - View Dependent Claims (8)
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9. A structure within a photodiode comprising:
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a semiconductor absorptive active layer for receiving and absorbing input light;
a light transmissive passivating layer forming a window over the semiconductor absorptive active layer within a contact structure, the contact structure comprising;
an electrically conductive alloyed material which forms a principal electrically conducting path to the semiconductor active layer from a contact region, said alloyed material having an opening therein surrounding the light transmissive passivating layer;
a reflector of highly reflective non-epitaxial-III-V, non-alloyed other material provided over the window and partially supported by an upper surface of the alloyed material about the window; and
a first layer and a second layer of light transmissive semiconductor material sandwiching the semiconductor absorptive active layer. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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Specification