Publication

Real-space Visualization of Energy Loss and Carrier diffusion in Nanowire Array using Four-Dimensional Electron Microscopy

Real-space Visualization of Energy Loss and Carrier diffusion in Nanowire Array using Four-Dimensional Electron Microscopy
Riya Bose, Jingya Sun,  Jafar I. Khan, Basamat S. Shaheen, Aniruddha Adhikari, Tien Khee Ng, V. M. Burlakov, Manas R. Parida, Davide Priante, A. Goriely, Boon S. Ooi, Osman M. Bakr, and Omar F. Mohammed
Advanced Materials, 28 (25), pp 5106-5111, (2016)
Riya Bose, Jingya Sun, Jafar I. Khan, Basamat S. Shaheen, Aniruddha Adhikari, Tien Khee Ng, V. M. Burlakov, Manas R. Parida, Davide Priante, A. Goriely, Boon S. Ooi, Osman M. Bakr, Omar F. Mohammed
Nanowire Array, Four-Dimensional Electron Microscopy
2016



Carrier diffusion and energy loss on nanomaterial surfaces are key determinants of overall performance in optoelectronic, photo-catalysis and photovoltaic devices. However, the ability to selectively access and explore such dynamical processes on nanomaterial surfaces with high spatial and temporal control is a particularly challenging task that can only be achieved by employing four-dimensional ultrafast electron microscopy (4D UEM) with time-resolved imaging capability. By using second generation scanning ultrafast electron microscopy (S-UEM) with a 650 femtoseconds and 5 nanometers temporal and spatial resolution capability respectively, we show that time resolved imaging of the energy loss dynamics and carrier spreading on the surfaces of a densely packed array of InGaN nanowires (NWs) as a model system can be achieved now in real space, providing direct and depth-selective information regarding surface dynamics which could not be accessed otherwise. Significantly, we modelled the variation in secondary-electron signal in time and space to extract fundamental materials parameters that describe carrier relaxation and diffusion processes in these nanomaterials.  Moreover, we identify the possible deactivation channels and the mechanism of secondary electron energy loss in the system, which will help unlock the full potential of this material for various applications.

DOI: 10.1002/adma.201600202