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HL: Halbleiterphysik

HL 14: Poster I

HL 14.82: Poster

Montag, 24. März 2003, 17:00–19:30, HSZ/P2

Direct patterning of GaN-heterostructures using an AFM with diamond tip — •A. Mühle¹, U. F. Keyser¹, R. J. Haug¹, E. Oesterschulze², and W. Knap³ — ¹Institut für Festkörperphysik, Universität Hannover — ²Institut für Technische Physik, Universität Kassel — ³G.E.S.-Université Montpellier, France

We use an atomic force microscope equipped with an all-diamond tip to directly manipulate the surface of a GaN-heterostructure. Our heterostructure contains a two-dimensional electron gas (2DEG) only 20 nm below the surface. For the first time we are able to directly influence the 2DEG with an AFM-based lithographic process.

By applying an extremely high contact force of several mN we fabricate shallow grooves on the surface of the GaN. This leads to a depletion of the 2DEG underneath the groove and thus a tunneling barrier is created.

We analyse the transport properties of these barriers by magneto-transport experiments in a perpendicular magnetic field and at variable temperatures. With a simple model calculation we are able to estimate the height and width of the tunneling barriers.