Nanowire-Heterojunction Bipolar Transistor (NW-HBT)
Final Report Abstract
For many years, the technological development of electronic devices has been pushed forward based on dimensional scaling. Translating lateral devices into novel geometries, including nanowires, opens up new functionalities with increased integration density, and enables heterointegration with a wide range of material combinations. Nanowire-based electronic devices published so far exhibited limited performance, which could be attributed to leakage currents and other undesired effects. In planar pn junctions, the current flow is determined by the minority carrier transport. In nanowires, additional currents are observed, which required an in-depth analysis deviating from the standard Shockley-Read-Hall model. Within the project, additional recombination due to electron tunneling could be identified and remedied by epitaxial design of the heterostructure junction. The finished project encompasses a comprehensive analysis of coaxial multi-shell nanowires in the GaAs/InGaP material system. Besides epitaxial synthesis and the following device process, fundamental insight was gained into the doping concentration within tapered nanowire cores and shells. Using a 4-tip scanning tunneling microscope, local conductivity measurements could be conducted on the nanowire structures. The electrical transport mechanisms could be separated by temperature-dependent current-voltage measurements across the pn junction within the nanowire. A cross-referencing of tunneling vs. diffusive current was enabled by electroluminescence spectroscopy and physical simulation of the semiconductor structures. With junctions optimized for tunneling current suppression, a first nanowire heterojunction npn bipolar transistor with more than unity current gain could be demonstrated. As a result, control of leakage currents is paramount for further development of nanowire-based electronic devices. Following this approach, high-resolution X-ray detection could be demonstrated in cooperation with the University of Jena, published in Nature Communications. This application case was not anticipated at the onset of the project, however, it demonstrates wide possibilities in the further use of nanowire devices, which could also be spurred by generated interest in the achieved publications with high impact factor.
Publications
- Comparative analysis on resistance profiling along tapered semiconductor nanowires: multitip technique versus transmission line method, Journal of Physics: Condensed Matter 29 (2017)
A Nägelein, L Liborius, M Steidl, C Blumberg, P Kleinschmidt, A Poloczek, T Hannappel
(See online at https://doi.org/10.1088/1361-648x/aa801e) - Towards Nanowire HBT: Reverse Current Reduction in Coaxial GaAs/InGaP n(i)p and n(i)pn Core-Multishell Nanowires Phys. Status Solidi A 216, 1800562, 2019
L Liborius, F Heyer, K Arzi, C Speich, W Prost, F-J Tegude, N Weimann, A Poloczek
(See online at https://doi.org/10.1002/pssa.201800562) - Hot electrons in a nanowire hard X-ray detector, Nature Comm 11 (1), 4729, 2020
M Zapf, M Ritzer, L Liborius, A Johannes, M Hafermann, S Schönherr, J Segura-Ruiz, G Martínez-Criado, W Prost, and C Ronning
(See online at https://doi.org/10.1038/s41467-020-18384-x) - n-Doped InGaP Nanowire Shells in GaAs/InGaP Core–Shell p–n Junctions, Phys. Status Solidi B, 257 (2) 1900358, 2020
L Liborius, J Bieniek, A Nägelein, F-J Tegude, W Prost, T Hannappel, A Poloczek, N Weimann
(See online at https://doi.org/10.1002/pssb.201900358) - Spatially Controlled VLS Epitaxy of Gallium Arsenide Nanowires on Gallium Nitride Layers, CrystEngComm 22 (17) 12339-1250, Feb. 2020
C Blumberg, L Liborius, J Ackermann, F-J Tegude, A Poloczek, W Prost, N Weimann
(See online at https://doi.org/10.1039/C9CE01926J) - Tunneling‐Related Leakage Currents in Coaxial GaAs/InGaP Nanowire Heterojunction Bipolar Transistors, Phys. Status Solidi B 258, 2000395, 2021
L Liborius, J Bieniek, A Poßberg, F-J Tegude, W Prost, A Poloczek, N Weimann
(See online at https://doi.org/10.1002/pssb.202000395)
