Photodiode arrangement

1. A photodiode arrangement, comprising:

an insulating layer; and

a silicon semiconductor layer having a plurality of portions with different thicknesses disposed on the insulating layer,

wherein each of the portions of the silicon semiconductor layer has a low-concentration diffusion region formed by diffusing one of a P-type impurity or an N-type impurity therein with a low concentration, a P-type high-concentration diffusion region formed by diffusing a P-type impurity therein with a high concentration, and an N-type high-concentration diffusion region formed by diffusing an N-type impurity therein with a high concentration,

wherein the P-type high-concentration diffusion region and the N-type high-concentration diffusion region formed in each portion of the silicon semiconductor layer are arranged to face each other, with the low-concentration diffusion region of the respective portion of the silicon semiconductor layer being interposed therebetween, and

wherein the low concentration diffusion region of one of the portions of the silicon semiconductor layer has a thickness which is less than a predetermined thickness, and each of the P-type high-concentration diffusion region and the N-type high-concentration diffusion region of that portion has the predetermined thickness, which ranges from 30 nm to 50 nm.

2. The photodiode arrangement according to claim 1 , wherein in each portion of the silicon semiconductor layer, the P-type high-concentration diffusion region and the N-type high-concentration diffusion region in that portion have thicknesses which are the same.

3. The photodiode arrangement according to claim 2 , wherein the plurality of portions of the silicon semiconductor layer have thicknesses which range from 3 nm to 50 nm.

4. The photodiode arrangement according to claim 1 , wherein the plurality of portions of the silicon semiconductor layer have thicknesses which range from 3 nm to 50 nm.

5. The photodiode arrangement according to claim 1 , wherein the P-type high-concentration diffusion region and the N-type high-concentration diffusion region in each portion have interdigitated comb-tooth projections.

6. A photodiode arrangement according to claim 1 , wherein the low-concentration diffusion region, the P-type high-concentration diffusion region, and the N-type high-concentration diffusion region are included in a photodiode forming region, and the photodiode forming region is surrounded by an element isolating layer.

7. A photodiode arrangement, comprising:

an insulating layer;

a silicon semiconductor layer disposed on the insulating layer, the silicon semiconductor layer having first and second portions and the second portion having a thickness which is less than that of the first portion;

a first photosensitive element which is formed in the first portion of the silicon semiconductor layer and in which a first P-type high-concentration diffusion region having a P-type impurity diffused therein with a high concentration and a first N-type high-concentration diffusion region having an N-type impurity diffused therein with a high concentration are arranged to face each other, with a first low-concentration diffusion region having one of a P-type impurity or an N-type impurity diffused therein with a low concentration being interposed therebetween; and

a second photosensitive element in which a second P-type high-concentration diffusion region having a P-type impurity diffused therein with a high concentration and a second N-type high-concentration diffusion region having an N-type impurity diffused therein with a high concentration are arranged to face each other, with a second low-concentration diffusion layer having one of a P-type impurity or an N-type impurity diffused therein with a low concentration being interposed therebetween,

wherein the second P-type high-concentration diffusion region and the second N-type high-concentration diffusion region are formed in the first portion of the silicon semiconductor layer, and

wherein the second low-concentration diffusion layer is formed in the second portion of the silicon semiconductor layer.

8. The photodiode arrangement according to claim 7 , wherein each of the first and second portions of the silicon semiconductor layer has a thickness ranging from 3 nm to 50 nm.

9. The photodiode arrangement according to claim 7 , wherein the first portion of the silicon semiconductor layer has a thickness ranging from 30 nm to 50 nm, and the second portion of the silicon semiconductor layer has a thickness ranging from 3 nm to 30 nm.

10. The photodiode arrangement according to claim 7 , wherein the first P-type high-concentration diffusion region and the first N-type high-concentration diffusion region have interdigitated comb-tooth projections, and the second P-type high-concentration diffusion region and the second N-type high-concentration diffusion region likewise have interdigitated comb-tooth projections.

11. A photodiode arrangement according to claim 7 , wherein the first photosensitive element and the second photosensitive element are surrounded by an element isolating layer respectively.

12. A photodiode arrangement, comprising:

an insulating layer;

a silicon semiconductor layer disposed on the insulating layer and having a first portion and a second portion that is insulated from the first portion, a first photosensitive element being fabricated on the first portion of the silicon semiconductor layer and a second photosensitive element being fabricated on the second portion of the silicon semiconductor layer, each of the first and second photosensitive elements including a P-type high-concentration diffusion region, an N-type high-concentration diffusion region, and a low-concentration doped diffusion region between the P-type and N-type high-concentration diffusion regions,

wherein the first portion of the silicon semiconductor layer has a first thickness at the low-concentration doped diffusion region of the first photosensitive element and the second photosensitive element has a second thickness at the low-concentration doped diffusion region of the second photosensitive element, the second thickness being smaller than the first thickness, and

wherein the P-type high-concentration diffusion region and the N-type high-concentration diffusion region of the first photosensitive element have the first thickness, and the P-type high-concentration diffusion region and the N-type high-concentration diffusion region of the second photosensitive element likewise have the first thickness.

13. A photodiode arrangement according to claim 12 , wherein the first thickness ranges from 30 nm to 50 nm and the second thickness ranges from 3 nm to 30 nm.

14. A photodiode arrangement according to claim 12 , wherein the first photosensitive element and the second photosensitive element are surrounded by an element isolating layer respectively.