Silicon sub-bandgap photon linear detection in two-photon experiments: A photo-assisted Shockley-Read-Hall mechanism

Abstract

We investigate the linear response of silicon p-i-n diodes to sub-bandgap photons (1.4 μm-1.6 μm) that has been reported by many authors and left unexplored till then. The quantum efficiency of this mechanism is extremely low (typically 10−9) but has a drastic influence on silicon devices harnessing two-photon absorption. We show that this linear photonic current decreases with temperature, displaying an activation energy similar to the dark current one. We show that this behaviour is consistent with a photo-assisted Shockley-Read mechanism in which the occupancy factor of a defect state in the Si band gap is influenced by the sub-band gap photon flux.

Competition between sub-bandgap linear detection and degenerate two-photon absorption in gallium arsenide photodiodes

“…The PASRH requires the existence of real electronic states inside the bandgap which are mostly due to defects in the semiconductor [10]. Thus, it is possible to retrieve the density of defects from our experiment.…”

“…• A significant decrease of the PASRH level, by either cooling the detector [10], or thanks to fewer interactions with trap levels in more controlled active medium and smaller interaction volumes.…”

“…However, our experiments did not show such a dependence for biases ranging from -1V to 0V, and we thus neglect this contribution. On the other hand, as it has been observed and described in silicon [10], PASRH is based on the ionization of traps from deep levels in the bandgap to the conduction band. This generationrecombination process is driven by the thermal agitation, meaning that PASRH is strongly temperature dependent.…”

Optimised bi-resonant nanostructured diode for infrared photodetection through non degenerate two-photon absorption

“…This phenomenon has been studied in several materials (silicium, gallium arsenide) and is explained as a photo-assisted Shockley-Read-Hall (PASRH) process. 6,7 The second term is the degenerate two-photon absorption of the pump. 3 The last one comes from the non-degenerate E-Mail : baptiste.fix@onera.fr two-photon absorption (NDTPA), which is the absorption of pump and signal photon.…”

Enhanced two-photon-absorption using sub-wavelength antennas

“…For TM-polarized light, the structure exhibits a resonance around 1.47 μm, with a strong field enhancement in the intrinsic region of the junction. We emphasize that the field is thus localized far from the interfaces, which effectively reduces the chances of having single-photon absorption (SPA) due to defect-assisted transitions at the interfaces, [16] while ensuring a high extraction rate of the free carriers. We demonstrate both numerically and experimentally that the TPA-photocurrent can be enhanced by at least two orders of magnitude at resonance, compared to a non-resonant PD.…”