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Substrate and Mg doping effects in GaAs nanowires
Perumal Kannappan1,2,3, Nabiha Ben Sedrine1, Jennifer P Teixeira1
1Departamento de Física & I3N, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
Beilstein Journal of Nanotechnology
|November 2, 2017
Summary
Magnesium (Mg) doping in Gallium Arsenide (GaAs) nanowires offers a promising route to p-type conductivity. Increasing Mg concentration impacts nanowire structure, optical properties, and electrical transport, with Mg potentially involved in radiative transitions on Si substrates.
Area of Science:
- Materials Science
- Nanotechnology
- Semiconductor Physics
Background:
- Magnesium (Mg) doping is a key method for achieving p-type conductivity in Gallium Arsenide (GaAs) nanowires, offering an alternative to Beryllium (Be).
- Limited research exists on the physical properties of intermediate-to-high Mg-doped GaAs nanowires grown via molecular beam epitaxy (MBE), particularly on GaAs(111)B and Si(111) substrates.
Purpose of the Study:
- To investigate the fundamental physical properties of Mg-doped GaAs nanowires with varying doping concentrations.
- To understand the influence of Mg doping on structural, optical, and electrical characteristics of GaAs nanowires grown on different substrates.
Main Methods:
- Growth of Mg-doped GaAs nanowires using molecular beam epitaxy (MBE) on GaAs(111)B and Si(111) substrates.
- Structural and optical characterization techniques to analyze nanowire properties.
- Fabrication of back-gate field-effect transistors (FETs) for individual nanowire electrical conductivity measurements.
Main Results:
- Increased Mg doping led to reduced polytypic influence on electronic structure and decreased vertical nanowire density, especially on Si(111).
- Higher Wurtzite (WZ) phase fraction was observed, particularly on Si(111), alongside increased activation energy for radiative states on GaAs(111)B.
- Electrical measurements revealed p-type conductivity with free hole concentrations from 2.7 × 10^16 to 1.4 × 10^17 cm^-3 and mobilities of 0.3-39 cm^2/Vs, with WZ/ZB interfaces as the dominant scattering mechanism.
Conclusions:
- Mg doping significantly influences the structural and electronic properties of GaAs nanowires, with substrate type playing a crucial role.
- Defects play a greater role in nonradiative de-excitation on Si(111) substrates, and Mg involvement in radiative transitions is suggested for these cases.
