As well as providing insight on the dependence of the output potential on doping, the team's calculations show that the potential drops mainly in the vicinity of the NW tip, across a region whose size increases as the doping decreases (see image). As a consequence, the output potential is essentially independent of the length of the NW.

Considering the case of a 1016 cm–3 doped NW, the output potential of about 42 mV is preserved even with very short NWs. When a force is applied to the NW, an effective negative charge is produced at the tip of the NW and electrons diffuse toward the base of the NW (which is kept to ground), creating a depletion region, which develops the output potential.

CMOS compatible

The work also highlights the importance of the dielectric material surrounding the nanowire on the output potential, which can be reduced significantly at low donor concentrations. These results are crucial for designing high-efficiency self-powered nanodevices. Furthermore, shorter NWs may easily be fabricated by wet-chemistry methods, which are fully compatible with low-cost, CMOS or MEMS processes.

The researchers presented their results in the journal Nanotechnology.