Thin Hydrogenated Amorphous Silicon Carbide Layers with Embedded Ge Nanocrystals

Area of Science:

• Materials Science
• Nanotechnology
• Semiconductor Physics

Background:

• Hydrogenated amorphous silicon carbide (a-SiC:H) is a promising material for optoelectronic applications.
• Integrating germanium nanocrystals (Ge NCs) can tune the optical and electronic properties of semiconductor films.

Purpose of the Study:

• To investigate the in situ integration of Ge NCs into a-SiC:H thin films.
• To characterize the structural and optical properties of the resulting nanocomposite films.
• To understand the impact of Ge NCs on charge carrier dynamics in a-SiC:H.

Main Methods:

• Plasma-enhanced chemical vapor deposition (PECVD) combined with vacuum evaporation for in situ Ge NC integration.
• Transmission electron microscopy (TEM) and energy-dispersive X-ray (EDX) spectroscopy for structural and compositional analysis.
• Photothermal deflection spectroscopy (PDS) and near-infrared photoluminescence (NIR PL) spectroscopy for optical characterization.

Main Results:

• Successful integration of Ge NCs within a-SiC:H thin films was confirmed.
• Ge NCs significantly increased optical absorption in the near-infrared (NIR) spectral region.
• Quenching of a-SiC:H NIR photoluminescence indicated a short charge carrier diffusion length (tens of nm) in the presence of Ge.
• Vacuum annealing at 550 °C degraded the optical properties of the a-SiC:H films.

Conclusions:

• In situ integration of Ge NCs into a-SiC:H is feasible, enhancing NIR absorption.
• The presence of Ge NCs limits charge carrier diffusion in a-SiC:H, suggesting potential applications where carrier confinement is beneficial.
• Thermal stability of the optical properties of these nanocomposite films needs further consideration.