Ge quantum dot memory structure with laterally ordered highly dense arrays of Ge dots

Area of Science:

• Materials Science
• Electrical Engineering
• Nanotechnology

Background:

• Development of advanced memory structures is crucial for next-generation electronics.
• Germanium (Ge) quantum dots offer promising properties for charge storage in memory devices.
• Achieving precise control over quantum dot arrangement is key to optimizing memory performance.

Purpose of the Study:

• To develop a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) type memory structure.
• To achieve lateral ordering of Ge quantum dots within the gate dielectric stack.
• To investigate the charging properties and limitations of the developed Ge quantum dot memory.

Main Methods:

• Fabrication involved focused ion beam (FIB) patterning, chemical treatments, and oxidation steps.
• Self-assembly of 2D arrays of Ge quantum dots on a patterned tunneling oxide.
• Electrical characterization using capacitance-voltage (C-V) measurements to assess charging properties.

Main Results:

• Successfully created laterally ordered Ge quantum dots within the gate dielectric.
• Electrical measurements showed a significant shift in C-V curves due to electron injection.
• Deep trap storage of charges led to difficult erasing and a limited memory window.

Conclusions:

• The study demonstrates a viable method for fabricating ordered Ge quantum dot memory structures.
• Controlled positioning of Ge quantum dots is achievable, but charge trapping presents a challenge.
• Further research is needed to overcome charge erasing limitations and enhance the memory window.