Demonstration of n-type behavior in catalyst-free Si-doped GaAs nanowires grown by molecular beam epitaxy

Ruhstorfer, Daniel; Mejia, Simon; Ramsteiner, Manfred; Doeblinger, Markus; Riedl, Hubert; Finley, Jonathan J. und Koblmueller, Gregor (2020): Demonstration of n-type behavior in catalyst-free Si-doped GaAs nanowires grown by molecular beam epitaxy. In: Applied Physics Letters, Bd. 116, Nr. 5, 052101

Abstract

The realization of n-type conduction in directly bottom-up grown Si-doped GaAs nanowires (NWs) by molecular beam epitaxy has remained a long-standing challenge. Unlike the commonly employed vapor-liquid-solid growth, where the amphoteric nature of Si dopants induces p-type conduction, we report a completely catalyst-free, selective area molecular beam epitaxial growth that establishes n-type behavior under Si doping. The vapor-solid selective area growth on prepatterned Si (111) substrates is enabled by an important in situ substrate pretreatment to create an As-terminated 1 x 1-Si(111) substrate necessary for the growth of [111]-oriented GaAs:Si NWs with a large aspect ratio and high yield. Correlated resonant Raman scattering and single-NW micro-photoluminescence (mu PL) experiments confirm the n-type nature of the Si-doped GaAs NWs evidenced by a dominant Si-Ga local vibrational Raman mode, a distinct band filling effect (up to > 10 meV) along with increased PL peak broadening upon increased Si concentration. Excessive Si doping is further found to induce some auto-compensation evidenced by red-shifted PL and the appearance of minor Si-As and Si-Ga-Si-As pair-like local vibrational Raman modes. Employing excitation power dependent mu PL, we further discern signatures in below-gap defect luminescence (similar to 1.3-1.45 eV) arising from structural defects and Si dopant-point defect complexes.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Chemie und Pharmazie > Department Chemie
• Themengebiete: 500 Naturwissenschaften und Mathematik > 540 Chemie
• ISSN: 0003-6951
• Sprache: Englisch