Dresden 2020 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 58: Nitrides: Preparation and characterization I
HL 58.5: Talk
Thursday, March 19, 2020, 10:30–10:45, POT 112
STEM and STEBIC analysis of screw dislocations in GaN to investigate structural and electronic properties — •Tobias Westphal1, Sevastian V. Shapenkov2, Oleg S. Vyvenko2, and Michael Seibt1 — 1University of Goettingen, IV. Physical Institute, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany — 2Faculty of Physics and IRC Nanotechnology Research Park, St. Petersburg State University, Ulyanovskaya 1, 198504, St. Petersburg, Russia
As GaN has a quite high grown-in dislocation density, in the order of 106 cm−2 - 108 cm−2 depending on the growth technique, investigating the electronic and optical properties of dislocations is of particular interest. Freshly introduced a-screw dislocations produced by indentations perpendicular to the basal (0001) plane of specially undoped low-resistance GaN show an intense dislocation related luminescence (DRL) with an energy peak at around 3.18 eV [1]. This red shift of about 300 meV with respect to the band gap can be explained by a dissociated dislocation, where the stacking fault ribbon forms a quantum well. Therefore, structural investigations of the dislocation core with high spatial resolution are of tremendous interest.
In this contribution, we report about STEM and scanning transmission electron beam induced current (STEBIC) measurements of dislocations in GaN. Measuring EBIC inside the TEM increases the spatial resolution compared to EBIC in the SEM, as the generation volume inside the sample is much smaller, which allows us to investigate single dislocations near the indentation prick.
[1] O. Medvedev et al., J. Appl. Phys. 123, 161427 (2018)