Hydrosoil, soil moisture and vegetation parameters retrieval with a C-Band GB-SAR: Campaign implementation and first results

HydroSoil is a measurement campaign, funded by the European Space Agency (ESA), where the temporal evolutions of two crops, barley and corn, have been continuously monitored during the whole crop period by means of a C-band Fully Polarimetric C-band Ground-Based Synthetic Aperture Radar (GB-SAR). SAR data has been collected together with ancillary data, and both are being processed to demonstrate the retrieval of soil moisture and vegetation parameters in an agricultural field under controlled conditions, to simulate the frequent acquisitions of GeoSAR missions.This work was funded by the European Space Agency (ESA Contract No. 4000132509/20/NL/FF/ab with UPC) and supported by the Spanish MCYT funds Unidad de Excelencia Maria de Maeztu MDM-2016-0600 and under project TEC2017-85244-C2-2-P. Special thanks to the Barcelona School of Agri-Food and Biosystems Engineering (EEABB) for making possible the radar deployment and the use of the experimental field.Peer ReviewedPostprint (author's final draft

High yield of gaas nanowire arrays on si mediated by the pinning and contact angle of Ga

Títol del preprint: Amorphous silicon mediates a high yield in GaAs nanowire arrays on Si.GaAs nanowire arrays on silicon offer great perspectives in the optoelectronics and solar cell industry. To fulfill this potential, gold-free growth in predetermined positions should be achieved. Ga-assisted growth of GaAs nanowires in the form of array has been shown to be challenging and difficult to reproduce. In this work, we provide some of the key elements for obtaining a high yield of GaAs nanowires on patterned Si in a reproducible way: contact angle and pinning of the Ga droplet inside the apertures achieved by the modification of the surface properties of the nanoscale areas exposed to growth. As an example, an amorphous silicon layer between the crystalline substrate and the oxide mask results in a contact angle around 90°, leading to a high yield of vertical nanowires. Another example for tuning the contact angle is anticipated, native oxide with controlled thickness. This work opens new perspectives for the rational and reproducible growth of GaAs nanowire arrays on silicon