Self-Powered Near-Infrared Photodetector Based on Asymmetrical Schottky Interdigital Contacts

Abstract

A self-powered metal-semiconductor Schottky diode with planar interdigital Au-Ti electrodes was fabricated and characterized for the detection of near-infrared light. The devices showed a significant increase in external quantum efficiency (EQE) and photoresponse at zero bias as electrode spacing reduces. A device with an electrode spacing of 5 μm exhibits EQE of 1% equivalent to responsivity of 6.45 mA/W at a wavelength of 800 nm and 0 V bias. Furthermore, the photocurrent to dark current ratio was 5×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> with a detectivity of 1.4×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sup> cm.Hz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.5</sup> /W at 0 V bias. The recovery time constant was calculated from time-resolved photocurrent curve and found to be 0.19 s. The built-in electric field of the device was estimated to be on the order of 35 V/cm.