US 11,742,452 B2
Inverted metamorphic multijunction solar cell
Clayton Cozzan, Albuquerque, NM (US); John Hart, Albuquerque, NM (US); Michael W. Riley, Los Lunas, NM (US); and Christopher Kerestes, Albuquerque, NM (US)
Filed by SolAero Technologies Corp., Albuquerque, NM (US)
Filed on Apr. 11, 2022, as Appl. No. 17/717,621.
Application 17/717,621 is a division of application No. 17/161,351, filed on Jan. 28, 2021.
Prior Publication US 2022/0254948 A1, Aug. 11, 2022
Int. Cl. H01L 31/054 (2014.01); H01L 31/0687 (2012.01); H01L 31/0725 (2012.01); H01L 31/0735 (2012.01); H01L 31/18 (2006.01)
CPC H01L 31/1844 (2013.01) [H01L 31/0543 (2014.12); H01L 31/0547 (2014.12); H01L 31/0687 (2013.01); H01L 31/0725 (2013.01); H01L 31/0735 (2013.01); H01L 31/1892 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A solar cell comprising:
an epitaxial sequence of layers of semiconductor material forming at least a top or light facing solar subcell and a second solar subcell having a top surface and a bottom surface and being disposed below the top or light facing solar subcell;
a semiconductor contact layer having a top surface and a bottom surface, the top surface of the semiconductor contact layer being disposed below the bottom surface of the second solar subcell;
a diffusion barrier layer below the bottom surface of the semiconductor contact layer, wherein the diffusion barrier layer has a thickness of between 0.1 nm and 10 nm, and wherein the diffusion barrier layer is composed of Pd or a Pd alloy;
a reflective metal layer having a thickness between 50 nm and 5 microns and being disposed below a bottom surface of the diffusion barrier layer, wherein reflectivity of the reflective metal layer is greater than 80% in the wavelength range 850-2000 nm for reflecting light back toward the second solar subcell; and
a contact metal layer composed of one or more layers of Ag, Au, and Ti disposed on a bottom of said reflective metal layer.