Generating ordered Si nanocrystals via atomic force microscopy

We describe two successful routes for generating ordered arrays of Si nanocrystals by using atomic force microscopy (AFM) and amorphous silicon thin films (200–400 nm) on Ti/Ni coated glass substrates. First, we show that field-enhanced metal-induced solid phase crystallization at room temperature can be miniaturized to achieve highly spatially localized (below 100 nm) current-induced crystallization of the amorphous silicon films using a sharp tip in AFM. In the second route, resistive nano-pits are formed at controlled positions in the amorphous silicon thin films by adjusting (lowering and/or stabilizing) the exposure currents in the AFM process. Such templated substrates are further used to induce localized growth of Si nanocrystals in plasma-enhanced chemical vapor deposition process. In both cases the crystalline phase is identified in situ as features of enhanced current in current-sensing AFM maps.

► We produce ordered crystalline features on a-Si:H films by 2 routes using AFM/CVD.
► The 1st route is using AFM to induce crystalline/non-crystalline pits on the a-Si.
► It is done by driving current through the film using the AFM tip as an electrode.
► Second route involves 2nd deposition of a mixed-phase Si film on pre-exposed films.
► After 2nd deposition we detect crystalline phase localized in previously a-Si pits.