Title: Graphene in 2D/3D heterojunctions for rectifying and photo-detecting applications Dr. Antonio Di Bartolomeo*, Giuseppe Luongo, Francesca Urban, Alessandro Grillo and Filippo Giubileo Professor University of Salerno, Physics Department “E.R. Caianiello” Italy Abstract The graphene/silicon (Gr/Si) junction has been the subject of intense research activity for both the easy fabrication and the variety of physical phenomena involved. It offers the opportunity to investigate new fundamental physics at the interface between a 2D semimetal and a 3D semiconductor, and holds promises for a new generation of graphene-based devices such as rectifiers, photodetectors, solar cells and chemical-biological sensors. A Gr/Si junction with defect-free interface exhibits rectifying current-voltage characteristics, owing to the formation of a Schottky barrier as in traditional metal-semiconductor (M/S) Schottky diodes [1]. The vanishing density of states at the graphene Dirac point enables Fermi level tuning and hence Schottky barrier height modulation by a single anode-cathode bias. When the Gr/Si junction is used as a photodetector, graphene acts as the transparent pick-up electrode as well as the active material for light absorption and electron-hole generation and separation. Although most of the incident light is converted into photo-charge inside Si, the absorbance in graphene enables detection of photons with Si sub-bandgap energy through internal photoemission over the Schottky barrier [2]. Photo-charges injected over the Schottky barrier, under high reverse bias, can be accelerated by the electric field in the depletion region of the diode and cause avalanche multiplication by scattering with the Si lattice, thus enabling internal gain. The Gr/Si junction forms the ultimate ultra-shallow junction, which is an ideal device to detect light absorbed very close to the Si surface, such as near- and mid-ultraviolet. In this talk, I start with some key features the graphene/semiconductor heterojunction, then I present the electrical characterization and the photo-response of two types of graphene/Si devices, on flat [3,4] and nanotip-patterned [5] Si-substrate, respectively. Although due to different mechanisms, for both devices, I demonstrate a photo-responsivity exceeding is competitive with present solid-state devices. I will show that the high responsivity can be attributed to charges photogenerated in the surrounding region of the flat junction [5] or to the internal gain by impact ionization caused by the enhanced field near the nanotips [4]. [1] A. Di Bartolomeo, Graphene Schottky diodes: An experimental review of the rectifying graphene/semiconductor heterojunction, Physics Reports 606 (2016) 1-58 [2] A. Di Bartolomeo et al., Graphene-Silicon Schottky Diodes for Photodetection, IEEE Transactions on Nanotechnology 17 (2018) 8408514, 1133-1137 [3] A. Di Bartolomeo et al., Hybrid graphene/silicon Schottky photodiode with intrinsic gating effect, 2D Materials 4 (2017) 025075 [4] G. Luongo et al. Electronic properties of graphene/p-silicon Schottky junction, Journal of Physics D: Applied Physics 51 (2018) 255305 [4] A. Di Bartolomeo et al., Tunable Schottky barrier and high responsivity in graphene/Si-nanotip optoelectronic device, 2D Materials 4 (2017) 015024 [5] G. Luongo et al., I-V and C-V Characterization of a High-Responsivity Graphene/Silicon Photodiode with Embedded MOS Capacitor, Nanomaterials 7 (2017) 158
Graphene in 2D/3D heterojunctions for rectifying and photo-detecting applications
Antonio Di Bartolomeo
Writing – Original Draft Preparation
2019-01-01
Abstract
Title: Graphene in 2D/3D heterojunctions for rectifying and photo-detecting applications Dr. Antonio Di Bartolomeo*, Giuseppe Luongo, Francesca Urban, Alessandro Grillo and Filippo Giubileo Professor University of Salerno, Physics Department “E.R. Caianiello” Italy Abstract The graphene/silicon (Gr/Si) junction has been the subject of intense research activity for both the easy fabrication and the variety of physical phenomena involved. It offers the opportunity to investigate new fundamental physics at the interface between a 2D semimetal and a 3D semiconductor, and holds promises for a new generation of graphene-based devices such as rectifiers, photodetectors, solar cells and chemical-biological sensors. A Gr/Si junction with defect-free interface exhibits rectifying current-voltage characteristics, owing to the formation of a Schottky barrier as in traditional metal-semiconductor (M/S) Schottky diodes [1]. The vanishing density of states at the graphene Dirac point enables Fermi level tuning and hence Schottky barrier height modulation by a single anode-cathode bias. When the Gr/Si junction is used as a photodetector, graphene acts as the transparent pick-up electrode as well as the active material for light absorption and electron-hole generation and separation. Although most of the incident light is converted into photo-charge inside Si, the absorbance in graphene enables detection of photons with Si sub-bandgap energy through internal photoemission over the Schottky barrier [2]. Photo-charges injected over the Schottky barrier, under high reverse bias, can be accelerated by the electric field in the depletion region of the diode and cause avalanche multiplication by scattering with the Si lattice, thus enabling internal gain. The Gr/Si junction forms the ultimate ultra-shallow junction, which is an ideal device to detect light absorbed very close to the Si surface, such as near- and mid-ultraviolet. In this talk, I start with some key features the graphene/semiconductor heterojunction, then I present the electrical characterization and the photo-response of two types of graphene/Si devices, on flat [3,4] and nanotip-patterned [5] Si-substrate, respectively. Although due to different mechanisms, for both devices, I demonstrate a photo-responsivity exceeding is competitive with present solid-state devices. I will show that the high responsivity can be attributed to charges photogenerated in the surrounding region of the flat junction [5] or to the internal gain by impact ionization caused by the enhanced field near the nanotips [4]. [1] A. Di Bartolomeo, Graphene Schottky diodes: An experimental review of the rectifying graphene/semiconductor heterojunction, Physics Reports 606 (2016) 1-58 [2] A. Di Bartolomeo et al., Graphene-Silicon Schottky Diodes for Photodetection, IEEE Transactions on Nanotechnology 17 (2018) 8408514, 1133-1137 [3] A. Di Bartolomeo et al., Hybrid graphene/silicon Schottky photodiode with intrinsic gating effect, 2D Materials 4 (2017) 025075 [4] G. Luongo et al. Electronic properties of graphene/p-silicon Schottky junction, Journal of Physics D: Applied Physics 51 (2018) 255305 [4] A. Di Bartolomeo et al., Tunable Schottky barrier and high responsivity in graphene/Si-nanotip optoelectronic device, 2D Materials 4 (2017) 015024 [5] G. Luongo et al., I-V and C-V Characterization of a High-Responsivity Graphene/Silicon Photodiode with Embedded MOS Capacitor, Nanomaterials 7 (2017) 158I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
