Patent ID: 8198706

Claim:
A method for making a multi-level nanowire structure, comprising: establishing a first plurality of nanowires on a substrate surface, wherein at least some of the nanowires of the first plurality are positioned i) at a predetermined crystallographically defined, non-perpendicular angle with respect to the substrate surface, ii) substantially perpendicular with respect to the substrate surface, or iii) combinations of i and ii; establishing an insulating layer between the nanowires of the first plurality such that one of two opposed ends of at least some of the nanowires positioned i) at the predetermined crystallographically defined, non-perpendicular angle with respect to the substrate surface, ii) substantially perpendicular with respect to the substrate surface, or iii) combinations of i and ii is exposed; growing, from each of the exposed ends, regions that coalesce to form a substantially continuous layer on the insulating layer, where the substantially continuous layer is connected to the exposed ends of the at least some of the nanowires of the first plurality; establishing a second plurality of nanowires on the substantially continuous layer such that at least some of the nanowires of the second plurality are positioned at different angles than at least some of the nanowires of the first plurality; establishing a second insulating layer between the nanowires of the second plurality such that one of two opposed ends of at least some of the nanowires of the second plurality is exposed; and growing, from each of the exposed ends of the at least some of the nanowires of the second plurality, second regions that coalesce to form a second substantially continuous layer on the insulating layer, where the substantially continuous layer is connected to the exposed ends of the at least some of the nanowires of the second plurality; wherein: the second substantially continuous layer is transparent to wavelengths of light to be detected by the nanowires of the first plurality and the nanowires of the second plurality; and a bandgap of the nanowires of the second plurality is larger than a bandgap of the nanowires of the first plurality.