Details

Autor(en) / Beteiligte

• Boland, Jessica L
• Conesa-Boj, Sonia
• Parkinson, Patrick
• Tütüncüoglu, Gözde
• Matteini, Federico
• Rüffer, Daniel
• Casadei, Alberto
• Amaduzzi, Francesca
• Jabeen, Fauzia
• Davies, Christopher L
• Joyce, Hannah. J
• Herz, Laura M
• Fontcuberta i Morral, Anna
• Johnston, Michael B

Titel

Modulation Doping of GaAs/AlGaAs Core–Shell Nanowires With Effective Defect Passivation and High Electron Mobility

Ist Teil von

• Nano letters, 2015-02, Vol.15 (2), p.1336-1342

Ort / Verlag

United States: American Chemical Society

Erscheinungsjahr

2015

Quelle

MEDLINE

Beschreibungen/Notizen

• Reliable doping is required to realize many devices based on semiconductor nanowires. Group III–V nanowires show great promise as elements of high-speed optoelectronic devices, but for such applications it is important that the electron mobility is not compromised by the inclusion of dopants. Here we show that GaAs nanowires can be n-type doped with negligible loss of electron mobility. Molecular beam epitaxy was used to fabricate modulation-doped GaAs nanowires with Al0.33Ga0.67As shells that contained a layer of Si dopants. We identify the presence of the doped layer from a high-angle annular dark field scanning electron microscopy cross-section image. The doping density, carrier mobility, and charge carrier lifetimes of these n-type nanowires and nominally undoped reference samples were determined using the noncontact method of optical pump terahertz probe spectroscopy. An n-type extrinsic carrier concentration of 1.10 ± 0.06 × 1016 cm–3 was extracted, demonstrating the effectiveness of modulation doping in GaAs nanowires. The room-temperature electron mobility was also found to be high at 2200 ± 300 cm2 V–1 s–1 and importantly minimal degradation was observed compared with undoped reference nanowires at similar electron densities. In addition, modulation doping significantly enhanced the room-temperature photoconductivity and photoluminescence lifetimes to 3.9 ± 0.3 and 2.4 ± 0.1 ns respectively, revealing that modulation doping can passivate interfacial trap states.