(488d) Unusual Nanoscale Electronic Effects and Carrier Dynamics in Heterojunction Nanowires

The unique electronic properties of quantum-confined semiconducting nanowires hold great promise for their incorporation in next-generation transistors, circuits, and electronic devices. This reduction in dimensionality results in a dramatic change in their carrier dynamics and electronic structure, [1-2] leading to novel properties such as ballistic transport and conductance quantization. One area of particular interest is the formation and understanding of electron gases in heterostructured nanowires which provides new avenues for exploring enhanced carrier dynamics in these materials.
In order to tailor these nanostructures with the desired physical properties, we must first understand their electronic properties as a function of size and material composition. To this end, we have developed a series of self-consistent predictive computational methods [1-3] to calculate the properties of heterojunction electron gases in quantum-confined core-shell nanowires. Under certain conditions (depending on doping density and spatial geometry), we find that quasi-one-dimensional electron gases can localize at the corners of the nanowire, leading to carrier dynamics that are dramatically different than analogous bulk heterojunctions. In addition, we highlight several areas where many-body quantum effects play a significant role in these low-dimensional structures. In particular, we surprisingly find that simple theoretical approaches can (1) considerably overestimate the number of occupied electron levels, (2) overdelocalize electrons, and (3) significantly underestimate the relative energy separation between electronic subbands. Our results allow a guided understanding of electron carrier dynamics in heterostructure nanowires and further indicate that electron gases in free-standing nanoscale systems are qualitatively different from their bulk counterparts.

[1] B.M. Wong, F. Leonard, Q. Li, and G.T. Wang, Nano Letters, 11, 3074 (2011).
[2] M. Fickenscher, T. Shi, H.E. Jackson, L.M. Smith, J.M. Yarrison-Rice, C. Zheng, P. Miller, J. Etheridge, B.M. Wong, Q. Gao, S. Deshpande, H.H. Tan and C. Jagadish, Nano Letters, 13, 1016 (2013).
[3] A.W. Long and B.M. Wong, AIP Advances, 2, 032173 (2012).