Photovoltaic device comprising compositionally graded intrinsic photoactive layer

• US 8,431,815 B2
• Filed: 12/22/2009
• Issued: 04/30/2013
• Est. Priority Date: 12/22/2009
• Status: Active Grant

• Current Assignee: TRIAD National Security, LLC
• Original Assignee: Los Alamos National Security LLC (Government of the United States of America)
• Inventors: Hoffbauer, Mark A., Williamson, Todd L.
• Primary Examiner(s): Johnson, Jonathan
• Assistant Examiner(s): TRINH, THANH TRUC
• Application Number:
  US12/644,915
• Publication Number:
  US 20110146769A1
• Time in Patent Office: 1,225 Days
• Field of Search: 136/255, 136/262, 136/256
• US Class Current: 136/255
• CPC Class Codes: C08J 7/123 Treatment by wave energy or particle radiation C08J7/18 takes precedence
• CPC Class Codes: H01L 31/028 including, apart from doping material or other impurities, only elements of Group IV of the Periodic Table
• CPC Class Codes: H01L 31/0296 including, apart from doping material or other impurities, only AIIBVI compounds, e.g. CdS, ZnS, HgCdTe
• CPC Class Codes: H01L 31/0304 including, apart from doping materials or other impurities, only AIIIBV compounds
• CPC Class Codes: H01L 31/03046 including ternary or quaternary compounds, e.g. GaAlAs, InGaAs, InGaAsP
• CPC Class Codes: H01L 31/0312 including, apart from doping materials or other impurities, only AIVBIV compounds, e.g. SiC
• CPC Class Codes: H01L 31/065 the potential barriers being only of the graded gap type
• CPC Class Codes: H01L 31/075 the potential barriers being only of the PIN type, e.g. amorphous silicon PIN solar cells
• CPC Class Codes: H01L 31/1844 comprising ternary or quaternary compounds, e.g. Ga Al As, In Ga As P
• CPC Class Codes: H01L 31/1852 comprising a growth substrate not being an AIIIBV compound
• CPC Class Codes: Y02E 10/544 Solar cells from Group III-V materials
• CPC Class Codes: Y02E 10/547 Monocrystalline silicon PV cells
• CPC Class Codes: Y02E 10/548 Amorphous silicon PV cells

Abstract

Photovoltaic devices and methods of making photovoltaic devices comprising at least one compositionally graded photoactive layer, said method comprising providing a substrate; growing onto the substrate a uniform intrinsic photoactive layer having one surface disposed upon the substrate and an opposing second surface, said intrinsic photoactive layer consisting essentially of In_1-xA_xN,; wherein:

• • i. 0≦x≦1;
  • ii. A is gallium, aluminum, or combinations thereof; and
  • iii. x is at least 0 on one surface of the intrinsic photoactive layer and is compositionally graded throughout the layer to reach a value of 1 or less on the opposing second surface of the layer;
    wherein said intrinsic photoactive layer is isothermally grown by means of energetic neutral atom beam lithography and epitaxy at a temperature of 600° C. or less using neutral nitrogen atoms having a kinetic energy of from about 1.0 eV to about 5.0 eV, and wherein the intrinsic photoactive layer is grown at a rate of from about 5 nm/min to about 100 nm/min.

Claims

1. A photovoltaic device comprising:

a transparent substrate;

a uniform, compositionally graded, intrinsic photoactive layer having one surface disposed upon the substrate and an opposing second surface, said intrinsic photoactive layer comprising In_1-xA_xN,;

wherein;

i. 0≦

x≦

1;

ii. A is gallium, aluminum, or combinations thereof; and

iii. x is at least 0 on one surface of the intrinsic photoactive layer and is compositionally graded throughout the layer to reach a value of 1 or less on the opposing second surface of the layer;

a p-type doped active layer region and an n-type doped active layer region, both regions being disposed upon the opposing second surface of the intrinsic photoactive layer, such that no portion of the p-type doped active layer region is in direct contact with the n-type doped active layer region;

an electrically conductive contact layer disposed upon the p-type doped active layer region and an electrically conductive contact layer disposed upon the n-type doped active layer region, such that no portion of the electrically conductive contact layer disposed upon the p-type doped active layer region is in contact with any portion of the electrically conductive contact layer disposed upon the n-type doped active layer region; and

,

a conductor to conduct electrons to an electrical circuit and in contact with the conducting contact layer.

2. The photovoltaic device of claim 1, wherein the p-doped active layer region and the n-doped active layer region each comprise a material having a lower band gap energy than the intrinsic photoactive layer.

3. The photovoltaic device of claim 1, wherein A is gallium.

4. The photovoltaic device of claim 1, wherein the intrinsic photoactive layer comprises a bandgap ranging from about 0.7 eV to about 3.4 eV.

5. The photovoltaic device of claim 1, wherein the photovoltaic device is a multi junction photovoltaic device and has an efficiency of at least 50%.

6. The photovoltaic device of claim 1, wherein the photovoltaic device is a multi junction photovoltaic device and has an efficiency of from about 30% to about 50%.

7. The photovoltaic device of claim 1, wherein the device is a single-junction photovoltaic device and has an efficiency of from about 10% to about 30%.