Graphene/SOI-based self-powered Schottky barrier photodiode array

Abstract

We have fabricated a four-element graphene/silicon on insulator (SOI) based Schottky barrier photodiode array (PDA) and investigated its optoelectronic device performance. In our device design, monolayer graphene is utilized as a common electrode on a lithographically defined linear array of n-type Si channels on a SOI substrate. As revealed by wavelength resolved photocurrent spectroscopy measurements, each element in the PDA structure exhibited a maximum spectral responsivity of around 0.1 A/W under a self-powered operational mode. Time-dependent photocurrent spectroscopy measurements showed excellent photocurrent reversibility of the device with ∼1.36 and ∼1.27 μs rise time and fall time, respectively. Each element in the array displayed an average specific detectivity of around 1.3 × 1012 Jones and a substantially small noise equivalent power of ∼0.14 pW/Hz−1/2. The study presented here is expected to offer exciting opportunities in terms of high value-added graphene/Si based PDA device applications such as multi-wavelength light measurement, level metering, high-speed photometry, and position/motion detection.

Self-powered photodetector array based on individual graphene electrode and silicon-on-insulator integration

“…Considering the Schottky-Mott model, where Φ B is defined as the difference between the work function of graphene (W G ) and the electron affinity of Si (χ Si = 4.05 eV), W G was calculated as ~4.86 eV in average for PD elements, respectively. These two diode parameters are consistent with our previous work [18] and those of G/n-Si based Schottky barrier photodiodes fabricated on thick n-Si substrates [26].…”

“…Contrary to previous studies based on the fabrication of single pixel G/n-Si Schottky devices with different architectures [15][16][17], our previous work showed that monolayer graphene can be utilized as a common electrode on a lithographically defined as linearly four channel n-type Si arrays on a SOI substrate [18]. In order to further minimize the possible optical crosstalk between elements and hence decrease the dark current in junction, it has become important to separate and disconnected individual graphene electrodes on every single Si element in the array and examine the device performances.…”

“…The spectral responsivity of diodes exhibits two maxima located at around 660 nm and 780 nm wavelengths and decays earlier for the wavelengths above 780 nm. As we explain in our previous work [18], this phenomena can be understood by the contribution of the drift and diffusion currents, penetration depth of light and reduced absorption coefficient of Si layer on SOI structure when compared with bulk Si substrate. Besides, the BOX and Si handle layer make ineffective the remaining light power for photoresponse gain in SOI structure [26].…”

“…After etching of possible FeCl 3 residues in H 2 O: HCl (3:1) solution, the PR/G became ready for transfer process. As distinct from our previous work 'G/n-Si PDA with common graphene electrode' fabrication route [18], large area grown monolayer graphene was transferred on arrayed SOI substrate following the fabrication of Si array and shaped with thick photoresist (t~15 µm) using photolithography, subsequently graphene was etched with O 2 plasma to separate graphene electrodes. Following the graphene etching procedure, the windows for metal contact pads were defined by an additional lithography step on individually separated elements.…”

“…To the best of our experience, optical crosstalk problem can be eliminated in graphene and Si based PDA fabrication as following ways; (i) using graphene as common electrode, or (ii) individually patterning graphene electrodes on a single substrate using SOI technology. In this regard, we separated graphene electrodes by adding graphene patterning step on our previous work [18] and we successfully obtained individual graphene electrodes on arrayed Si channels and investigated the optoelectronic characteristics of each element. The scope of this work lies in the improvement of SOI based G/n-Si Schottky barrier PDAs with separate graphene electrode.…”