SEMICONDUCTOR PHOTO-DETECTING DEVICE
A photo-detecting device includes a first semiconductor layer, a second semiconductor layer located on the first semiconductor layer, a light-absorbing layer located between the first semiconductor layer and the second semiconductor layer, and a first interface between the second semiconductor layer and the light-absorbing layer. The second semiconductor layer includes a first region having a first dopant and a second region surrounding the first region. The light-absorbing layer includes a third region having the first dopant and a fourth region surrounding the third region. The first dopant of the first region close to the first interface has a first doping concentration, and the first dopant of the third region close to the first interface has a second doping concentration larger than the first doping concentration.
1 . A photo-detecting device, comprising:
a first semiconductor layer;
a second semiconductor layer located on the first semiconductor layer and comprising a first region and a second region surrounding the first region, wherein the first region comprises a first dopant;
a light-absorbing layer located between the first semiconductor layer and the second semiconductor layer and comprising a third region and a fourth region surrounding the third region, wherein the third region comprises the first dopant; and
a first interface between the second semiconductor layer and the light-absorbing layer;
wherein the first dopant of the first region close to the first interface comprises a first doping concentration and the first dopant of the third region close to the first interface comprises a second doping concentration, and the second doping concentration is larger than the first doping concentration.
2 . The photo-detecting device of claim 1 , wherein the third region of light-absorbing layer has a thickness which is in a range of 0.1 μm to 1 μm.
3 . The photo-detecting device of claim 1 , wherein the first dopant has a first diffusion coefficient in the second semiconductor layer and a second diffusion coefficient in the light-absorbing layer, and the first diffusion coefficient is greater than the second diffusion coefficient.
4 . The photo-detecting device of claim 3 , wherein the first diffusion coefficient is in a range of 10 −14 cm 2 /s and 10 −13 cm 2 /s.
5 . The photo-detecting device of claim 3 , wherein the second diffusion coefficient is in the range of 10 −16 cm 2 /s and 10 −14 cm 2 /s.
6 . The photo-detecting device of claim 1 , wherein the second semiconductor layer comprises a second dopant in the first region and the second region, and the second dopant is different from the first dopant.
7 . The photo-detecting device of claim 6 , wherein the first region has a first conductivity-type, and the second region has a second conductivity-type different from the first conductivity-type.
8 . The photo-detecting device of claim 6 , wherein in the first region, the first dopant has a doping concentration greater than that of the second dopant.
9 . The photo-detecting device of claim 1 , further comprising a diffusion barrier layer between the second semiconductor layer and the light-absorbing layer, and the diffusion barrier layer comprising a fifth region corresponding to the first region and a sixth region surrounding the fifth region, wherein the fifth region comprises the first dopant.
10 . The photo-detecting device of claim 9 , wherein the first dopant has a third doping concentration in the fifth region, and the third doping concentration is larger than the second doping concentration.
11 . The photo-detecting device of claim 9 , wherein the first dopant has a first diffusion coefficient in the second semiconductor layer, a second diffusion coefficient in the light-absorbing layer and a third diffusion coefficient in the diffusion barrier layer, and the first diffusion coefficient is greater than the second diffusion coefficient and the third diffusion coefficient.
12 . The photo-detecting device of claim 11 , wherein the third diffusion coefficient is smaller than the second diffusion coefficient.
13 . The photo-detecting device of claim 11 , wherein the diffusion barrier layer has a thickness less than that of the light-absorbing layer.
14 . The photo-detecting device of claim 1 , further comprising an insulating layer covering the second region.
15 . The photo-detecting device of claim 14 , further comprising an electrode structure located on the insulating layer and connecting the first region.
16 . The photo-detecting device of claim 1 , wherein the first dopant comprises a doping profile with a peak within the third region.
17 . The photo-detecting device of claim 1 , wherein the first dopant comprises a doping profile, along a direction from the second semiconductor layer to the light-absorbing layer, the doping profile is decreased in the first region, increased at the first interface, and then decreased at the third region.
18 . The photo-detecting device of claim 17 , wherein the first dopant has a first decreased gradient rate in the first region and a second decreased gradient rate in the third region, and the second decreased gradient rate is larger than the first decreased gradient rate.
19 . A photo-detecting module, comprising:
a light-emitting device;
the photo-detecting device of claim 1 ; and
a carrier electrically connecting to the light-emitting device and the photo-detecting device.
20 . The photo-detecting device of claim 19 , further comprising a first trench and a second trench, and the light-emitting device and the photo-detecting device are disposed in the first trench and the second trench respectively.