We report on the electrical and optical properties of microcrystal arrays obtained by depositing Ge on a deeply patterned Si substrate. Finite difference time domain simulations indicate that the faceted morphology and high refractive index of Ge microcrystals lead to strong light trapping effects, enhancing infrared light absorption in the spectral window between the direct and indirect absorption edge of Ge (asymptotic to 1550-1800 nm). This is experimentally confirmed by fabricating microcrystal-based Ge-on-Si photodiodes employing graphene as a top transparent contact. In these devices, the ratio between the responsivities at 1550 and 1700 nm is more than ten times larger than that of photodiodes based on conventional Ge-on-Si epilayers.

Graphene/Ge microcrystal photodetectors with enhanced infrared responsivity

Falcone, V;Ballabio, A;Barzaghi, A;Zucchetti, C;Anzi, L;Bottegoni, F;Frigerio, J;Sordan, R;Biagioni, P;Isella, G
2022

Abstract

We report on the electrical and optical properties of microcrystal arrays obtained by depositing Ge on a deeply patterned Si substrate. Finite difference time domain simulations indicate that the faceted morphology and high refractive index of Ge microcrystals lead to strong light trapping effects, enhancing infrared light absorption in the spectral window between the direct and indirect absorption edge of Ge (asymptotic to 1550-1800 nm). This is experimentally confirmed by fabricating microcrystal-based Ge-on-Si photodiodes employing graphene as a top transparent contact. In these devices, the ratio between the responsivities at 1550 and 1700 nm is more than ten times larger than that of photodiodes based on conventional Ge-on-Si epilayers.
File in questo prodotto:
File Dimensione Formato  
5.0082421.pdf

accesso aperto

: Publisher’s version
Dimensione 7.44 MB
Formato Adobe PDF
7.44 MB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11311/1219508
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 0
  • ???jsp.display-item.citation.isi??? 0
social impact