Photovoltaic ultraviolet sensor
A photovoltaic ultraviolet sensor comprises a zinc oxide single crystal substrate. On the +c face of the zinc oxide single crystal substrate, an ultraviolet receiver is formed. The exemplary ultraviolet receiver includes a Schottky electrode which, when receiving ultraviolet rays, produces a voltage in cooperation with the zinc oxide single crystal substrate. The ultraviolet sensor does not have any sensitivity to the visible rays. The ultraviolet sensor has a relatively fast response of several microseconds.
1. A photovoltaic ultraviolet sensor comprising: a zinc oxide single crystal having a +c face and a −c face opposite to the +c face; and an ultraviolet receiver which is formed on the +c face of the zinc oxide single crystal and, when receiving ultraviolet rays, produces a voltage solely or in cooperation with the zinc oxide single crystal, wherein the ultraviolet receiver comprises a Schottky electrode formed on the +c face of the zinc oxide single crystal, and wherein the photovoltaic ultraviolet sensor further comprising an Al doped ZnO layer formed on the −c face of the zinc oxide single crystal.
2. The photovoltaic ultraviolet sensor according to claim 1 , wherein the ultraviolet receiver comprises an adjustment thin film directly formed on the +c face of the zinc oxide single crystal and a Schottky electrode formed on the adjustment thin film.
3. The photovoltaic ultraviolet sensor according to claim 2 , wherein the adjustment thin film comprises a zinc oxide based thin film.
4. The photovoltaic ultraviolet sensor according to claim 3 , wherein the zinc oxide based thin film comprises at least one layer which is an element selected from the group consisting of Ca, Mg, S, Al, Cd, Se, Ga, N, Cu and Te.
5. The photovoltaic ultraviolet sensor according to claim 2 , wherein the adjustment thin film comprises a nitride thin film.
6. The photovoltaic ultraviolet sensor according to claim 5 , wherein the nitride thin film comprises at least one layer which is an element selected from the group consisting of Ga, Al and In.
7. The photovoltaic ultraviolet sensor according to claim 1 , wherein the Schottky electrode is ultraviolet-permeable.
8. The photovoltaic ultraviolet sensor according to claim 1 , wherein the Schottky electrode comprises one or more layers, each of which is made of Pt, Ru, Pd, Au, Ni, Ir, Os, Re, Rh, Te or W.
9. The photovoltaic sensor according to claim 1 , further comprising an antireflection film, wherein the ultraviolet receiver has a receiving portion, and the antireflection film covers the receiving portion.
10. The photovoltaic ultraviolet sensor according to claim 9 , wherein the antireflection film has a thickness of 1 to 200 nm.
11. The photovoltaic ultraviolet sensor according to claim 9 , wherein the antireflection film is ultraviolet-permeable.
12. The photovoltaic ultraviolet sensor according to claim 9 , wherein the antireflection film comprises one or more layers, each of which is made of Al 2 O 3 , SiO 2 , SiNO, SiN, ZnS or ZnO.
13. The photovoltaic ultraviolet sensor according to claim 1 , further comprising a passivation film, wherein the zinc oxide single crystal has a first peripheral region on the +c face of the zinc oxide single crystal, the ultraviolet receiver has a second peripheral part positioned on the first peripheral region, and the passivation film covers at least one of the first peripheral region and the second peripheral part.
14. The photovoltaic ultraviolet sensor according to claim 13 , wherein the passivation film comprises at least a layer made of Al 2 O 3 , SiO 2 , SiNO, SiN, AIN, SIALON, ZnS or ZnO.
15. The photovoltaic ultraviolet sensor according to claim 1 , wherein the zinc oxide single crystal is one obtainable by carrying out a heat treatment for a base material of zinc oxide single crystal under an oxygen-containing atmosphere within a container made of zinc oxide.
16. The photovoltaic ultraviolet sensor according to claim 1 , wherein the Schottky electrode is formed directly on the +c face of the zinc single crystal.