Regensburg 2019 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 31: Nitrides: Preparation and characterization II

HL 31.8: Vortrag

Mittwoch, 3. April 2019, 17:00–17:15, H31

Ultrathin GaN/InN/GaN QW structures grown by MBE — •Frederik Lüßmann, Tobias Meyer, Jörg Malindretos, Michael Seibt, and Angela Rizzi — Georg-August Universität Göttingen, IV. Physikalisches Institut, 37077 Göttingen

Lately, topological insulators (TIs) have drawn much attention as a new state of quantum matter. In particular, two-dimensional TIs can be achieved by growing QWs with an inverted band structure. For InN/GaN it has been predicted that the large piezoelectric fields in pseudomorphic QWs grown along the [0001] direction can trigger band inversion. The minimum critical thickness of InN for the topological phase transition is expected to be about 4 MLs. In this study we therefore aim at the fabrication of ultrathin pseudomorphic InN/GaN QWs. The samples are grown by MBE and analysed by AFM, STEM and PL. We have examined a growth mode, already known in literature, in which InN QWs are grown at elevated substrate temperatures of 620^∘C to 670^∘C, which is well above the dissociation temperature of InN. The high In supply and the subsequent capping with GaN are expected to induce a phase separation resulting in stable InN layer. Furthermore, segregation of the excess In occurs at the growing GaN cap surface. In this way, very well defined and sharp QWs can be grown, as shown by STEM. Sharp PL emission at low temperature also indicates the successful growth of the QW structures.