Photodiode
AssigneeSumitomo Electric Industries, Ltd.
InventorsYoshiki Kuhara, Yasuhiro Iguchi
Life of this patent
Estimating the term…
Abstract
A photodiode that is used in an optical communication system using two different wavelengths, λ1 and λ2 (λ1<λ2), and that enables a reduction in the optical crosstalk caused by outgoing light having a longer wavelengths, λ2. A photodiode that receives light having a shorter wavelengths, λ1, is provided with an absorption layer made of a mate having a bandgap wavelength, λg. (λ1<λg<λ2), to detect the light having λ1. A filter layer that absorbs unwanted light having λ2 is provided over the absorption layer so that the light having λ2 cannot return to the absorption layer after passing through it once.
Claims10
A back-illuminated-type photodiode that concurrently admits light having a longer wavelength, λ2, and light having a shorter wavelength, λ1, and that detects only the light having a shorter wavelength, λ1, which photodiode comprising:
- (a) a semiconductor substrate;
- (b) an absorption layer being:
- (b1) placed on the semiconductor substrate;
- (b2) provided with a pn junction in the layer;
- and
- (b3) made of a semiconductor material having a bandgap wavelength, λg, longer than λ1 and shorter than λ2;
- (c) a cap layer being:
- (c1) placed on the absorption layer;
- and
- (c2) made of a material that absorbs light having the wavelength λ2;
- (d) a first electrode being:
- (d1) placed on the bottom surface of the semiconductor substrate;
- and
- (d2) provided with an opening for admitting light;
- and
- (e) a second electrode being:
- (e1) placed on the cap layer;
- and
- (e2) provided with an opening for allowing light to leave the photodiode.
A back-illuminated-type photodiode that concurrently admits light having a longer wavelength, λ2, and light having a shorter wavelength, λ1, and that detects only the light having a shorter wavelength, λ1, which photodiode comprising:
- (a) a semiconductor substrate;
- (b) an absorption layer being:
- (b1) placed on the semiconductor substrate;
- (b2) provided with a pn junction in the layer;
- and
- (b3) made of a semiconductor material having a bandgap wavelength, λg, longer than λ1 and shorter than λ2;
- (c) a cap layer placed on the absorption layer;
- (d) a filter layer being:
- (d1) placed on the center portion of the cap layer;
- and
- (d2) made of a material that absorbs light having the wavelength λ2;
- (e) a first electrode being:
- (e1) placed on the bottom surface of the semiconductor substrate;
- and
- (e2) provided with an opening for admitting light;
- and
- (f) a second electrode being:
- (f1) placed on the filter layer;
- and
- (f2) provided with an opening for allowing light to leave the photodiode.
A back-illuminated-type photodiode that concurrently admits light having a longer wavelength, λ2, and light having a shorter wavelength, λ1, and that detects only the light having a shorter wavelength, λ1, which photodiode comprising:
- (a) a semiconductor substrate;
- (b) an absorption layer being:
- (b1) placed on the semiconductor substrate;
- (b2) provided with a pn junction in the layer;
- and
- (b3) made of a semiconductor material having a bandgap wavelength, λg, longer than λ1 and shorter than λ2;
- (c) a cap layer placed on the absorption layer;
- (d) a filter layer being:
- (d1) placed on the center portion of the cap layer;
- and
- (d2) made of a material that absorbs light having the wavelength λ2;
- (e) a first electrode being:
- (e1) placed on the bottom surface of the semiconductor substrate;
- and
- (e2) provided with an opening for admitting light;
- and
- (f) a second electrode placed at the outside of the filter layer, thereby forming an opening for allowing light to leave the photodiode.
A back-illuminated-type photodiode that concurrently admits light having a longer wavelength, λ2, and light having a shorter wavelength, λ1, and that detects only the light having a shorter wavelength, λ1, which photodiode comprising:
- (a) a semiconductor substrate;
- (b) an absorption layer being:
- (b1) placed on the semiconductor substrate;
- (b2) provided with a pn junction in the layer;
- and
- (b3) made of a semiconductor material having a bandgap wavelength, λg, longer than λ1 and shorter than λ2;
- (c) a cap layer placed on the absorption layer;
- (d) a first electrode being:
- (d1) placed on the bottom surface of the semiconductor substrate;
- and
- (d2) provided with an opening for admitting light;
- (e) a second electrode being:
- (e1) placed on the cap layer;
- and
- (e2) provided with an opening for allowing light to leave the photodiode;
- and
- (f) a plastic resin being:
- (f1) applied in such a manner as to form the topmost layer of the photodiode;
- and
- (f2) capable of absorbing light having the wavelength λ2.
Dependencies are inferred from the claim text.