Proposal of a broadband, polarization-insensitive and high-efficiency hot-carrier schottky photodetector integrated with a plasmonic silicon ridge waveguide

Abstract

We propose a polarization-insensitive and high-efficiency plasmonic silicon Schottky diode for detection of sub-bandgap photons in the optical communication wavelength range through internal photoemission. Our photodiode is based on a hybrid plasmonic silicon waveguide. It has a gold film covering both the top and the sidewalls of a dielectric silicon waveguide with the Schottky contact formed at the gold-silicon interface. An extensive physical model is presented in detail and applied to calculate and analyze the performance of our detector. By comparison with a diode with only top contact of gold, the polarization sensitivity of responsivity is greatly minimized in our photodetector with sidewall coverage of gold.Much higher responsivities for both polarizations are also achieved in a very broad wavelength range of 1.2-1.5 μm. Moreover, the Schottky contact is only 4 μm long, leading to a very small dark current. Our design is very promising for practical applications in high-density silicon photonic integration.Internal photoemission (IPE) is an intrinsic property of a Schottky diode, occurring at a metal-semiconductor interface [1]. In IPE, three processes are involved.Firstly, an electron (hole) in the metal is excited to a higher level after absorbing a photon, becoming a hot electron (hot hole). Secondly, the hot carrier (electron or hole) travels to the metal-semiconductor interface. During its travel, the hot carrier may lose some energy due to scattering by cold carriers or by thermal relaxation. Finally, upon

Broadband Absorption and Efficient Hot-Carrier Photovoltaic Conversion based on Sunlight-induced Non-radiative Decay of Propagating Surface Plasmon Polaritons

“…Each time the hot electron reaches the Au-TiO 2 interface, it will have a probability for emission. Therefore, P ( E ) in this case is the sum of all the probabilities for all the round trips, as expressed below 27 :where E i  =  E 0  exp(−2i t Au /MFP) is the energy of a hot electron after traveling i (=0, 1,…, N )-number round trips within the Au film and the corresponding emission probability, P ( E i ), can be expressed as according to Equation (4). Therefore, the more round trips the hot electron experiences, the larger the total IPE probability becomes.…”

“…The excited surface plasmons can decay either radiatively by re-emitting photons or non-radiatively through generation of energetic carriers (i.e., hot electrons and hot holes) via Landau damping 2 – 4 . Before thermal relaxation, these hot carriers can be extracted via plasmon-enhanced internal photoemission (IPE) 5 , 6 by e.g., contacting the metal with a semiconductor forming a metal-semiconductor Schottky junction 7 – 27 . In this process, the hot carriers are able to jump over the Schottky barrier at the metal-semiconductor interface as long as their energies are larger than the barrier height.…”

Surface plasmon enhanced photodetectors based on internal photoemission

“…A polarization-insensitive and high-efficiency plasmonic subbandgap Si Schottky photodetector operating at telecom wavelengths via IPE is proposed in Ref. 91. The proposed structure, shown in Fig.…”

Plasmonic photodetectors based on asymmetric nanogap electrodes

“…However, despite the fact is that the hot electrons arriving at the metal=semiconductor interface can be reflected in the vast majority of cases, there is still a possibility for them to pass the Au-Si interface after multiple times of scattering events, and two assumptions are made based on this phenomenon: 20) (1) If the hot electrons cannot travel through the Au-Si interface, they will make it to the interface in an elastic collision; (2) The electrons cannot travel through the Auvacuum interface or escape into vacuum, but they can make it to the interface in an elastic collision. Then, taking the reflecting events into account, the emission probability of a hot carrier every time is presented in Fig.…”