Compound semiconductor solar cell and method of manufacturing the same
Disclosed is a method of manufacturing a compound semiconductor solar cell according to an embodiment of the invention. The method of manufacturing the compound semiconductor solar cell according to the embodiment of the invention includes forming a plurality of compound semiconductor layers of at least two elements and including a base layer and an emitter layer, the base layer including a first conductivity type dopant to have a first conductivity type and the emitter layer including a second conductivity type dopant to have a second conductivity type. The forming of the plurality of compound semiconductor layers includes at least one of a process-temperature change period and a growth-rate change period.
1. A method of manufacturing a compound semiconductor solar cell, the method comprising:
forming a plurality of compound semiconductor layers of at least two elements, the plurality of compound semiconductor layers including a base layer and an emitter layer, the base layer including an n type dopant to have an n type and the emitter layer including a p type dopant to have a p type,
wherein the forming of the plurality of compound semiconductor layers includes at least one of a process-temperature change period and a growth-rate change period,
wherein the forming of the plurality of compound semiconductor layers comprises:
forming a p type semiconductor layer including the emitter layer and having the p type; and
forming an n type semiconductor layer on the p type semiconductor layer,
wherein the n type semiconductor layer includes the base layer and has the n type, and
wherein the forming of the n type semiconductor layer includes a period having a processing temperature lower than a processing temperature of the forming of the p type semiconductor layer, or a process temperature to form the base layer is lower than a process temperature to form the emitter layer.
2. The method of claim 1 , wherein at least one of the base layer and the emitter layer comprises a compound semiconductor layer including gallium (Ga), indium (In) and phosphorus (P) as one of the at least two elements.
3. The method of claim 1 , wherein the process-temperature change period comprises a process-temperature decreasing period in which a process temperature decreases.
4. The method of claim 1 , wherein the forming of the plurality of compound semiconductor layers includes a plurality of processes including an initial process and a final process, and
wherein a process temperature of the final process is lower than a process temperature of the initial process.
5. The method of claim 3 , wherein the process-temperature change period comprises at least one of a stepwise decreasing portion in which the process temperature is stepwisely decreased and a gradual decreasing portion in which the process temperature is gradually decreased.
6. The method of claim 3 , wherein the process-temperature change period includes a plurality of process-temperature change periods, and a temperature change by each of the plurality of process-temperature change periods is 5° C. or more.
7. The method of claim 1 , wherein the growth-rate change period comprises a growth-rate increasing period in which a growth rate increases.
8. The method of claim 1 , wherein the forming of the plurality of compound semiconductor layers includes a plurality of processes including an initial process and a final process, and
wherein a growth rate of the final process is greater than a growth rate of the initial process.
9. The method of claim 7 ,
wherein the forming of the n type semiconductor layer includes a period having a growth rate greater than a growth rate in the forming of the p type semiconductor layer; or
wherein a growth rate to form the base layer is lower than a growth rate to form the emitter layer.
10. The method of claim 9 , wherein a thickness of the base layer is greater than a thickness of the emitter layer.
11. The method of claim 9 , wherein the forming of the n type semiconductor layer comprises:
forming the base layer; and
forming a contact layer on the base layer,
wherein the contact layer is formed of a material different from a material of the base layer, and
wherein the contact layer is thinner than the base layer or has a thickness of 30 to 150 nm.
12. The method of claim 7 , wherein the growth-rate change period includes a plurality of growth-rate change periods, and
wherein a growth-rate change by each of the plurality of growth-rate change periods is 0.1 μm/hr or more.
13. The method of claim 7 , wherein the growth-rate change period comprises at least one of a stepwise increasing portion in which the growth rate is stepwisely increased and a gradual increasing portion in which the growth rate is gradually increased.
14. The method of claim 1 ,
wherein the base layer has the n-type,
wherein the base layer comprises a gallium-indium-phosphorous (GaInP) layer, and
wherein the emitter layer comprises a gallium-indium-phosphorus (GaInP) layer or an aluminum-gallium-indium-phosphorus (AlGaInP) layer.
15. The method of claim 1 , further comprising, before the forming of the plurality of compound semiconductor layers:
forming another photoelectric conversion unit; and
forming a tunnel junction layer on the another photoelectric conversion unit,
wherein the compound semiconductor solar cell has a multi-junction structure.