We propose a hybrid device consisting of a graphene/silicon (Gr/Si) Schottky diode in parallel with a Gr/SiO2/Si capacitor for high-performance photodetection. The device, fabricated by transfer of commercial graphene on low-doped n-type Si substrate, achieves a photoresponse as high as 3 AW−1 and a normalized detectivity higher than 3.5×1012 cmHz1/2 W−1 in the visible range. It exhibits a photocurrent exceeding the forward current because photo-generated minority carriers, accumulated at Si/SiO2 interface of the Gr/SiO2/Si capacitor, diffuse to the Gr/Si junction. We show that the same mechanism, when due to thermally generated carriers, although usually neglected or disregarded, causes the increased leakage often measured in Gr/Si heterojunctions. We perform extensive I–V and C-V characterization at different temperatures and we measure a zero-bias Schottky barrier height of 0.52 eV at room temperature, as well as an effective Richardson constant A** = 4×10−5 A cm−2 K−2 and an ideality factor n3.6, explained by a thin (<1 nm) oxide layer at the Gr/Si interface.
|Titolo:||Hybrid graphene/silicon Schottky photodiode with intrinsic gating effect|
|Data di pubblicazione:||2017|
|Appare nelle tipologie:||1.1.1 Articolo su rivista con DOI|