Substrate diode effect on the performance of Silicon Germanium phototransistors

Zerihun Gedeb Tegegne (1) , Carlos Viana (1) , Marc D. Rosales (2) , Jean-Luc Polleux (1) , Catherine Algani (3, 1) , Marjorie Grzeskowiak (1) , Elodie Richalot (1)

1 ESYCOM - Electronique, Systèmes de communication et Microsystèmes
2 UP System - University of the Philippines
3 CNAM - Conservatoire National des Arts et Métiers [CNAM]

This paper provides a study on the substrate effect on the opto-microwave behavior of Silicon-Germanium Heterojunction bipolar Photo-Transistors (HPT). An Opto-Microwave Scanning Near Field Optical Microscopy (OM-SNOM) is performed to observe the distribution of photocurrent and dynamic behavior over the structure of the phototransistor. The photocurrent generated in the photodiode created by a n++ sub-collector and p+ substrate is extracted and analyzed. A maximum substrate diode current of 700μA is observed at 850nm with a related cutoff frequency of 0.42GHz. We have extracted low frequency responsivity (at 50MHz) bandwidth product of 109.2 MHzA/W. Finally, this study will provide a design guide line for Si base phototransistors.

Mots clés: Substrate effet; Silicon-based photodetectors; Microwave-photonics; Phototransistor; SiGe HPT; Radio-over-Fiber; Opto-microwave performances

Domaines: Electromagnétisme

Zerihun Gedeb Tegegne, Carlos Viana, Marc D. Rosales, Jean-Luc Polleux, Catherine Algani, et al.. Substrate diode effect on the performance of Silicon Germanium phototransistors. 2015 International Topical Meeting on Microwave Photonics (MWP), Oct 2015, Paphos, Cyprus. pp.1-4, ⟨10.1109/MWP.2015.7356678⟩. ⟨hal-01708918⟩