Many approaches have illustrated the capability of fabricating highly crystalline Ge nanodots. However, intermixing of Si and Ge due to the high temperature of the annealing treatment is still a severe problem. This may degrade the performance and decrease the efficiency of the Ge nanodot devices. In addition, the uniformity of the Ge nanodots needs to be further improved for practical applications.

Room-temperature fabrication

The researchers propose a novel method to fabricate an array of pure Ge nanodots for NVM at room temperature. These nanodots have excellent size uniformity and distribution patterns.

First, amorphous Ge nanodots with controlled size, density and distribution are defined by an electron-beam-lithography system (Japanese Elionix ELS-7000). These nanodots are then capped with a SiO2 layer and subsequently irradiated with UV radiation using a pulsed excimer laser.

Hysteresis characteristics

In the electrical characterisation of capacitance-voltage, the NVM device exhibits clear hysteresis characteristics. The obvious memory window can also be used to define ‘1’ and ‘0’ states at program operation.

The researchers presented their work in the journal Nanotechnology 26 165301.

Further reading

Heat-assisted magnetic recording doubles hard disk drive capacity (Jun 2014)
Rare-Earth oxides for silicon-germanium quantum dot memories (Nov 2013)
Tunnelling electroresistance in multiferroic heterostructures (Dec 2014)