Efficient electron and hole doping in compositionally abrupt Si/Ge nanowires

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Efficient doping of semiconductor nanowires (NWs) is crucial for advanced electronic devices.
• Compositionally abrupt SiGe NWs offer unique electronic properties but present doping challenges.

Purpose of the Study:

• To investigate the impact of various dopant elements (P, N, Al, B, O) on the electronic properties of different SiGe NW architectures.
• To elucidate the role of interfacial geometry in determining doping efficiency in SiGe NWs.

Main Methods:

• Density-functional theory (DFT) calculations were employed to simulate doping effects.
• Three types of SiGe NWs were studied: Ge(core)/Si(shell), Si(core)/Ge(shell), and fused triangular-prism SiGe NWs.

Main Results:

• Pentavalent P substitution at the Ge/Si interface in Ge/Si NWs efficiently injects free electrons.
• Trivalent Al or B substitution at the Si/Ge interface effectively injects free holes.
• Divalent O substitution in triangular-prism SiGe NWs induces hole carriers at low temperatures.

Conclusions:

• Doping efficiency in SiGe NWs is significantly influenced by both dopant type and the specific interfacial geometry.
• This research provides a framework for designing and synthesizing SiGe NWs with tailored doping characteristics.