QDev Seminar: Adam Micolich

Professor, School of Physics, The University of New South Wales, Sydney, Australia.

New materials for nanoelectronics: Ultrathin Parylene insulators, p-GaAs nanowire transistors and InAs nanofin Hall bars

Innovation in electronic devices is heavily driven by advances in materials and materials combinations. I will report on three such advances that my group has been working on in the past 2-3 years. The first is the development of InAs nanofin Hall bars grown by selective-area epitaxy [1]. These are freestanding rectangular InAs structures with base-length 1-2 mm, height 4-5 mm and thickness 80-150 nm (see Fig. a/b). The relatively large area enables devices with multiple contacts for four-terminal resistance and Hall effect measurements, as well as top-gates (see Fig. c). The presence of a surface 2DEG layer generates interesting physics that mixes effects from bilayer 2D systems and semiconductor billiards.

The second and third relate to advancements in nanowire transistor technology. One is the development of nanowire transistors utilising the organic insulator parylene [2]. A key benefit of parylene is the ability to preserve semiconductor surface chemistry under the gate insulator, and it also provides biocompatible coatings for bioelectronics applications. We discuss an approach to producing devices with ultrathin (< 100 nm) parylene insulators and their performance as n-type InAs nanowire transistors.

Finally, I will show results from the development of p-type GaAs nanowire transistors. We obtain Schottky-gated FETs with sub-threshold slope within 4% of the room temperature thermal limit and competitive performance on on-off ratio, on-resistance and operating speed [3]. Our devices provide an interesting alternative to p-GaSb nanowires, and since high-performance n-GaAs nanowire FETs also exist, open a path to all-GaAs nanowire MESFET complementary circuits.

[1] J. Seidl, J.G. Gluschke, H.H. Tan, C. Jagadish, A.P. Micolich & P. Caroff, Manuscript in Preparation.

[2] J.G. Gluschke, J. Seidl, R.W. Lyttleton, D.J. Carrad, J.W. Cochrane, S. Lehmann, L. Samuelson & A.P. Micolich, Nano Lett. 18, 4431 (2018).

[3] A.R. Ullah, F. Meyer, J.G. Gluschke, S. Naureen, P. Caroff, P. Krogstrup, J. Nygård & A.P. Micolich, Nano Lett. 18, 5673 (2018).