Quantum Dot Photovoltaic Device and Manufacturing Method Thereof

• US 20110146775A1
• Filed: 08/28/2009
• Published: 06/23/2011
• Est. Priority Date: 08/28/2008
• Status: Active Grant

• Current Assignee: Korea Research Institute of Standards and Science
• Original Assignee: Korea Research Institute of Standards and Science
• Inventors: Kim, Kyung Joong, Yun, Wan Soo, Hong, Seung hui, Kim, Young Heon, Kang, Sang Woo, Lee, Woo, Kim, Yong Sung
• Granted Patent: US 8,603,849 B2
• Time in Patent Office: Days
• US Class Current: 136/255
• CPC Class Codes: H01L 31/035218 the quantum structure being quantum dots
• CPC Class Codes: H01L 31/18 Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
• CPC Class Codes: Y02E 10/50 Photovoltaic [PV] energy

Abstract

The present invention provides a semiconductor based photovoltaic device and a manufacturing method thereof. The semiconductor based photovoltaic device is able to absorb light with a wide band wavelength, and has high photoelectric conversion efficiency since it has high electron-hole pair separation efficiency. More specifically, the method for manufacturing the photovoltaic device comprises the steps of: a) forming a thin semiconductor quantum dot film on a p or n-type semiconductor substrate, wherein the thin semiconductor quantum dot film includes semiconductor quantum dots inside a medium at which the same type of impurities as the semiconductor substrate are doped; b) forming a pore array through partial etching, wherein the pore array penetrates the thin semiconductor quantum dot film; c) depositing a semiconductor in which complementary impurities to the semiconductor substrate are doped on the thin semiconductor quantum dot film at which the pore array is formed; and d) forming sequentially a transparent conductive film and an upper electrode on the semiconductor in which the complementary impurities are doped and forming a lower electrode at a lower portion of the semiconductor substrate.

Claims

1. A method of manufacturing a photovoltaic device, comprising:

a) forming, on an upper surface of a p-type or n-type semiconductor substrate, a thin semiconductor quantum dot film in which semiconductor quantum dots are formed in a medium doped with the same type of impurities as the semiconductor substrate;

b) forming an array of pores which perforate the thin semiconductor quantum dot film using partial etching;

c) depositing a semiconductor doped with complementary impurities to the semiconductor substrate on the thin semiconductor quantum dot film having the array of pores; and

d) sequentially forming a transparent conductive film and an upper electrode on the semiconductor doped with the complementary impurities, and forming a lower electrode on a lower surface of the semiconductor substrate.

2. The method of claim 1, wherein a) comprises:

a1-1) repetitively forming a medium layer containing a semiconductor nitride, a semiconductor oxide or a mixture thereof doped with the same type of impurities as the semiconductor substrate and a semiconductor layer on the upper surface of the semiconductor substrate, thus forming a multilayered composite layer; and

a1-2) annealing the multilayered composite layer so that semiconductor quantum dots are formed in the medium containing the semiconductor nitride, the semiconductor oxide or the mixture thereof doped with the same type of impurities as the semiconductor substrate, and then performing annealing in a hydrogen atmosphere, thus linking nonbonding electrons of the semiconductor quantum dots with hydrogen.

3. The method of claim 1, wherein a) comprises:

a2-1) forming, on the upper surface of the semiconductor substrate, a non-stoichiometric compound layer containing a semiconductor oxide, a semiconductor nitride or a mixture thereof doped with the same type of impurities as the semiconductor substrate and having an oxygen or nitrogen deficient non-stoichiometric ratio; and

a2-2) annealing the non-stoichiometric compound layer thus forming semiconductor quantum dots in the medium containing the semiconductor nitride, the semiconductor oxide or the mixture thereof doped with the same type of impurities as the semiconductor substrate, and then performing annealing in a hydrogen atmosphere thus linking nonbonding electrons of the semiconductor quantum dots with hydrogen.

4. The method of claim 2, wherein the multilayered composite layer in a1-1) is formed using deposition including PVD (Physical Vapor Deposition), CVD (Chemical Vapor Deposition) or ALD (Atomic Layer Deposition), and the medium layer and the semiconductor layer of the multilayered composite layer have each independently a thickness ranging from 1 nm to 5 nm.

5. The method of claim 4, wherein semiconductor layers of the multilayered composite layer have different thicknesses, and become larger in thickness as they are positioned closer to the semiconductor substrate.

6. The method of claim 3, wherein the non-stoichiometric compound layer in a2-1) is formed using deposition including PVD (Physical Vapor Deposition), CVD (Chemical Vapor Deposition) or ALD (Atomic Layer Deposition), and the semiconductor oxide or semiconductor nitride contained in the non-stoichiometric compound layer has an oxygen or nitrogen deficiency of 0˜

50% compared to an oxygen or nitrogen content necessary for bonding satisfying a stoichiometric ratio, and has an oxygen or nitrogen content gradient in a thickness direction of the non-stoichiometric compound layer.

7. The method of claim 6, wherein the oxygen or nitrogen content gradient is such that the oxygen or nitrogen content decreases towards the semiconductor substrate.

8. The method of claim 1, wherein b) comprises:

b1) forming a mask on an upper surface of the thin semiconductor quantum dot film; and

b2) transferring a pattern of the mask using RIE (Reactive Ion Etching), thus forming the array of pores that perforate the thin semiconductor quantum dot film.

9. The method of claim 8, wherein a short-axis diameter of the pores formed using RIE in b2) ranges from 20 nm to 1000 nm.

10. The method of claim 1, wherein the photovoltaic device is a silicon photovoltaic device;

the semiconductor quantum dots are silicon quantum dots; and

the medium is silicon oxide, silicon nitride or a mixture thereof.

11. A photovoltaic device, comprising:

a lower electrode;

an n-type or p-type first semiconductor layer formed on the lower electrode;

a porous semiconductor quantum dot layer having a plurality of semiconductor quantum dots formed in a medium doped with the same type of impurities as the first semiconductor layer and including a plurality of through pores;

a second semiconductor layer in contact with the porous semiconductor quantum dot layer and comprising a semiconductor material doped with complementary impurities to the first semiconductor layer; and

a transparent conductive film and an upper electrode sequentially formed on the second semiconductor layer.

12. The photovoltaic device of claim 11, wherein the semiconductor quantum dots of the porous semiconductor quantum dot layer have different sizes, and become larger in size as they are positioned closer to the first semiconductor layer.

13. The photovoltaic device of claim 11, wherein a p-n junction is formed on a surface defined by the through pores that perforate the porous semiconductor quantum dot layer, and the medium is in a state of a built-in depletion layer by the p-n junction.

14. The photovoltaic device of claim 11, wherein the photovoltaic device is a silicon photovoltaic device;

the semiconductor quantum dots are silicon quantum dots; and

the medium is silicon oxide, silicon nitride or a mixture thereof