Photoelectric conversion element and imaging device
A photoelectric conversion element is formed by laminating, in order, a substrate, a lower electrode, an organic layer which generates electric charge by light irradiation, an upper electrode which transmits light, a buffer layer and a protective film. The buffer layer is formed from hydrogenated silicon oxide containing hydrogen ions, and has a thickness of 1 to 100 nm. The protective film contains hydrogenated silicon nitride containing hydrogen ions or hydrogenated silicon oxynitride containing hydrogen ions and has a thickness of 30 to 500 nm.
1. A photoelectric conversion element comprising:
a substrate;
a lower electrode formed on the substrate;
an organic layer formed on the lower electrode and adapted to generate electric charges in response to irradiation with light;
an upper electrode formed on the organic layer and adapted to transmit the light;
a buffer layer formed on the upper electrode; and
a protective film formed on the buffer layer,
wherein the buffer layer is composed of hydrogenated silicon oxide having a hydrogen ion content of 10 atm % to 40 atm % and has a thickness of 1 nm to 100 nm; and
wherein the protective film is composed of hydrogenated silicon nitride containing hydrogen ions or hydrogenated silicon oxynitride containing hydrogen ions and has a thickness of 30 nm to 500 nm.
2. The photoelectric conversion element according to claim 1 , wherein the buffer layer contains no element nitrogen.
3. The photoelectric conversion element according to claim 1 , wherein the protective film has an internal stress of 100 MPa or less as expressed in absolute value.
4. The photoelectric conversion element according to claim 1 , wherein the buffer layer and the protective film are formed by a vapor phase film formation method.
5. The photoelectric conversion element according to claim 1 , wherein the upper electrode has a thickness of 5 nm to 30 nm.
6. The photoelectric conversion element according to claim 1 , wherein the hydrogenated silicon oxynitride is expressed by a formula: SiOxNy:H [where x>0.5 and y>0.6], and has a hydrogen ion content of 10 atm % to 40 atm %.
7. The photoelectric conversion element according to claim 1 , wherein the light includes at least visible light;
wherein the organic layer generates electric charges in response to irradiation of the light including at least visible light; and
wherein the upper electrode is formed of a conductive material showing transparency with respect to the light including at least visible light.
8. The photoelectric conversion element according to claim 1 , wherein the organic layer includes a photoelectric conversion layer that is formed on a side closer to the upper electrode and that is adapted to generate electric charges according to an amount of received light, and an electron blocking layer that is formed at a side closer to the lower electrode and that is adapted to inhibit electrons from being injected into the photoelectric conversion layer from the lower electrode.
9. The photoelectric conversion element according to claim 8 , wherein the photoelectric conversion layer has a thickness of 10 nm to 1000 nm.
10. The photoelectric conversion element according to claim 8 , wherein the electron blocking layer has a thickness of 20 nm to 300 nm.
11. An imaging device comprising the photoelectric conversion element according to claim 1 .
12. The photoelectric conversion element according to claim 1 , wherein the hydrogenated silicon oxynitride is expressed by a formula: SiOx:H [where 1.3 <x <2.2].
13. The photoelectric conversion element according to claim 1 , wherein the buffer layer prevents an influence exerted by NH 3 gas and by radicals and ions generated from the NH 3 gas.
14. The photoelectric conversion element according to claim 1 , wherein the buffer layer has a refractive index of 1.50 or less at 550 nm.
15. The photoelectric conversion element according to claim 1 ,
wherein the buffer layer is formed by a plasma-enhanced CVD method, NH 3 gas is used as a process gas, a film formation temperature of the buffer layer is 125° C. to 250° C., and
wherein the protective film is formed by a plasma-enhanced CVD method, at least two of SiH 4 gas, NH 3 gas and N 2 O gas are used as a process gas, a film formation temperature of the buffer layer is 125° C. to 250° C.