Photoelectric conversion device and manufacturing method thereof
View Patent ↗A photoelectric conversion device with a novel anti-reflection structure. In the photoelectric conversion device, a front surface of a semiconductor substrate which serves as a light-receiving surface is covered with a group of whiskers (a group of nanowires) so that surface reflection is reduced. In other words, a semiconductor layer which has a front surface where crystals grow so that whiskers are formed is provided on the light-receiving surface side of the semiconductor substrate. The semiconductor layer has a given uneven structure, and thus has effects of reducing reflection on the front surface of the semiconductor substrate and increasing conversion efficiency.
1. A photoelectric conversion device comprising:
a semiconductor substrate having a front surface and a back surface, wherein the back surface of the semiconductor substrate is provided with an n-type impurity region and a p-type impurity region;
a metal layer over the front surface;
a plurality of whiskers over the metal layer, wherein the plurality of whiskers comprises a crystalline semiconductor;
a first electrode on the n-type impurity region;
a second electrode on the p-type impurity region,
wherein each of the plurality of the whiskers comprises a protrusion with a diameter of greater than or equal to 500 nm and less than or equal to 3 μm, and a length of greater than or equal to 1 μm and less than or equal to 100 μm, and
wherein a reflectance of the plurality of the whiskers is less than or equal to 5%.
2. A photoelectric conversion device according to claim 1 , further comprising: an insulating film formed over the plurality of whiskers.
3. A photoelectric conversion device according to claim 1 ,
wherein the n-type impurity region contains an n-type impurity element added by a doping method, and
wherein the p-type impurity region contains a p-type impurity element added by a doping method.
4. A photoelectric conversion device according to claim 1 ,
wherein the p-type impurity region comprises a first p-type impurity region and a second p-type impurity region, and
wherein a first impurity concentration of the first p-type impurity region is different from a second impurity concentration of the second p-type impurity region.
5. A photoelectric conversion device comprising:
a semiconductor substrate having a front surface and a back surface, wherein the back surface of the semiconductor substrate is provided with an n-type impurity region and a p-type impurity region;
a metal layer over the front surface;
a plurality of whiskers over the metal layer, wherein the plurality of whiskers comprises a crystalline semiconductor;
an insulating film on the n-type impurity region and the p-type impurity region;
a first electrode on the insulating film; and
a second electrode on the insulating film,
wherein the first electrode is electrically connected to the n-type impurity region through a contact hole in the insulating film,
wherein the second electrode is electrically connected to the p-type impurity region through a contact hole in the insulating film,
wherein each of the plurality of the whiskers comprises a protrusion with a diameter of greater than or equal to 500 nm and less than or equal to 3 μm, and a length of greater than or equal to 1 μm and less than or equal to 100 μm, and
wherein a reflectance of the plurality of the whiskers is less than or equal to 5%.
6. A photoelectric conversion device according to claim 5 , further comprising: an insulating film formed over the plurality of whiskers.
7. A photoelectric conversion device according to claim 5 ,
wherein the n-type impurity region contains an n-type impurity element added by a doping method, and
wherein the p-type impurity region contains a p-type impurity element added by a doping method.
8. A photoelectric conversion device according to claim 5 ,
wherein the p-type impurity region comprises a first p-type impurity region and a second p-type impurity region, and
wherein a first impurity concentration of the first p-type impurity region is different from a second impurity concentration of the second p-type impurity region.
9. The photoelectric conversion device according to claim 1 ,
wherein the metal layer is any one selected in a group of platinum, aluminum, copper, titanium, and an aluminum.
10. The photoelectric conversion device according to claim 5 ,
wherein the metal layer is any one selected in a group of platinum, aluminum, copper, titanium, and an aluminum.