GUIDED GROWTH OF HORIZONTAL ZnSe NANOWIRES AND THEIR INTEGRATION INTO HIGH-PERFORMANCE BLUE-UV PHOTODETECTORS

The organization of nanowires on surfaces is one of the main obstacles toward their large-scale integration into functional devices. Recently, our group developed a new bottom-up approach of “guided growth” (Science 2011, 333, 1003), demonstrating horizontal growth of nanowires along specific directions of a substrate, producing perfectly aligned arrays of nanowires. Horizontal growth of semiconductor nanowires has been implemented with several materials and substrates, but to date, none of them have band gap energies in the visible range on a transparent substrate, such as needed for optoelectronic applications. In the present manuscript, we report the guided growth of horizontally aligned ZnSe nanowires with either wurtzite (hexagonal) or zincblende (cubic) structure and different crystallographic orientations, which are exquisitely controlled by the epitaxial relations with different planes of sapphire. This is, to the best of our knowledge, the first report of horizontal nanowires of a visible-range optoelectronic material on a transparent substrate. The guided growth enables the parallel integration of the nanowires of this important optoelectronic material into blue-UV photodetectors, exhibiting the lowest dark current and the fastest measured rise and decay times for devices based on ZnSe 1D nanostructures.