SOLAR CELL AND MANUFACTURING METHOD THEREOF
A solar cell includes a base layer including a first conductive type impurity element, an upper surface, and a lower surface opposing the upper surface, an emitter layer disposed on the upper surface of the base layer and including a second conductive type impurity element opposing the first conductive type impurity element, a front electrode connected to the emitter layer, a first passivation layer disposed on the lower surface of the base layer, and a rear electrode disposed on the first passivation layer and connected to the base layer. The first passivation layer includes a silicon nitride group compound, and a refractive index of the silicon nitride group compound is less than about 1.96.
1 . A solar cell comprising:
a base layer including a first conductive type impurity element from a first Group of elements, an upper surface, and a lower surface opposing the upper surface;
an emitter layer on the upper surface of the base layer and including a second conductive type impurity element from a second Group of elements different from the first Group;
a front electrode connected to the emitter layer;
a first passivation layer on the lower surface of the base layer; and
a rear electrode on the first passivation layer and connected to the base layer,
wherein the first passivation layer includes a silicon nitride group compound, and a refractive index of the silicon nitride group compound is equal to or less than about 1.96.
2 . The solar cell of claim 1 , wherein
the refractive index of the silicon nitride group compound is in a range of about 1.8 to about 1.96.
3 . The solar cell of claim 2 , wherein
a light absorption coefficient of the first passivation layer is equal to or less than about 0.01.
4 . The solar cell of claim 3 , further comprising
a second passivation layer between the lower surface of the base layer and the first passivation layer.
5 . The solar cell of claim 4 , wherein
the second passivation layer includes of aluminum oxide.
6 . The solar cell of claim 5 , further comprising
a reflection prevention layer on the emitter layer.
7 . The solar cell of claim 6 , wherein
the front electrode is extended through the reflection prevention layer, and is connected to the emitter layer.
8 . The solar cell of claim 1 , wherein
a portion of the rear electrode is extended through the first passivation layer, and is connected to the base layer.
9 . The solar cell of claim 8 , further comprising
a rear electric field layer on the lower surface of the base layer, the first passivation layer being between the rear electric field layer and the base layer.
10 . The solar cell of claim 1 , wherein the first Group and the second Group are selected from International Union of Pure and Applied Chemistry Groups III and V elements.
11 . A method manufacturing a solar cell, the method comprising:
forming a base layer including a first conductive type impurity element from a first Group of elements, an upper surface, and a lower surface opposing the upper surface;
forming an emitter layer on the upper surface of the base layer, and including a second conductive type impurity element from a second Group of elements opposing the first Group of elements;
forming a first passivation layer on the lower surface of the base layer;
forming a second passivation layer on the first passivation layer; and
forming a front electrode connected to the emitter layer, and a rear electrode on the second passivation layer and connected to the base layer,
wherein the second passivation layer includes a silicon nitride group compound, and a refractive index of the silicon nitride group compound is equal to or less than about 1.96.
12 . The method of claim 11 , wherein
the refractive index of the silicon nitride group compound is in a range of about 1.8 to about 1.96.
13 . The method of claim 12 , wherein
a light absorption coefficient of the second passivation layer is equal to or less than about 0.01.
14 . The method of claim 13 , further comprising
forming a reflection prevention layer on the emitter layer.
15 . The method of claim 14 , wherein
the first passivation layer is formed of aluminum oxide.
16 . The method of claim 11 , wherein
the forming a second passivation layer includes plasma-enhanced chemical vapor deposition.
17 . The method of claim 11 , wherein
the forming a second passivation layer includes forming the silicon nitride group compound by using a raw gas including silane or ammonia.
18 . The method of claim 17 , wherein
the raw gas for the formation of the silicon nitride group compound further includes nitrogen.
19 . The method of claim 18 , wherein
the forming a second passivation layer includes a process condition that gas flows of the silane, the ammonia, and the nitrogen are respectively 1000 standard cubic centimeters, 15,000 standard cubic centimeters, and 18,000 standard cubic centimeters.