We report an individually addressable Ti/GaAs metal-semiconductor hybrid optical nanosensor with positive photoresistance and a sensitivity that increases as the device dimensions shrink. The underlying physics relates to the crossover from ballistic to diffusive transport of the photoinduced carriers and the geometric enhancement of the effect associated with a Schottky-barrier-coupled parallel metal shunt layer. For a 250 nm device under 633 nm illumination we observe a specific detectivity of D* =5.06× 1011 cm Hz/W with a dynamic response of 40 dB.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)