Novel nano-materials approaches towards opto-electronics and energy applications
Lars Samuelson
Lund University, NanoLund and Solid State Physics, Box 118, SE-221 00 Lund, Sweden lars.samuelson@ftf.lth.se also Founder and Chief Scientist of QuNano AB, Glo AB, Sol Voltaics AB and Hexagem AB.

In spite of often superior properties, in terms of materials and device performance, compound semi- conductors like GaAs and GaN often encounter difficulties in market acceptance, in most cases due to issues of fabrication costs. Nanowires (NWs) constitute a special case due to the opportunities they offer to form highly ideal one-dimensional materials that can be designed into three-dimensional heterostructures via axial as well as radial heterostructures, furthermore with the ability as a technology to add compound semiconductor functionality to a silicon platform. I will structure this presentation into three areas:
(1) The development of high-quality GaN nanowires forming the basis for visible light-emitting diodes [1], primarily with application opportunities in displays, presently with a huge potential market in the areas of micro-LEDs for direct-view displays.
(2) Know-how gained from nitride NW nucleation offers a technology base for realization of relaxed and dislocation-free, c-oriented GaN and InGaN platelets and wafers [2] of significant value for directly driven RGB-emitting LEDs. Many applications areas for nitrides, for optics as well as RF/Power-applications, need higher quality, low dislocation density, wafers.
(3) Opportunities to drastically reduce cost of NW fabrication, based on a dramatically novel growth approach, which we have given the name Aerotaxy [3], by which NWs are grown in an aerosol phase, without use of substrates. I will discuss means by which such NWs may be processed into thin films, thus bridging the many orders of magnitude from discrete NW-devices to square-meter scale applications like for solar cells [4, 5].

References

[1] B. Monemar et al., “Nanowire-Based Visible Light Emitters, Present Status and Outlook”, Chapter 7 in Semiconductors and Semimetals 94, 227-271 (2016).
[2] L. Samuelson et al., “Gallium nitride nano-sized LEDs”, SPIE newsroom, 10.1117/2.1201603.006385 (2016).
[3] M. Heurlin et al., “Continuous gas-phase synthesis of nanowires with tunable properties”, Nature Vol. 492, 90 (2012)
[4] J. Wallentin et al., “InP Nanowire Array Solar Cells Achieving 13.8% Efficiency by Exceeding the Ray Optics Limit”, Science Vol 339, 1057 (2013)
[5] I. Ã…berg et al., “A GaAs Nanowire Array Solar Cell with 15.3% Efficiency at 1 sun”, IEEE Journal of Photovoltaics Vol. 6, 185 (2016)