Plasmon-enhanced Ge-based metal-semiconductor-metal photodetector at near-IR wavelengths

Abstract

We demonstrate the use of plasmonic effects to boost the near-infrared sensitivity of metal-semiconductor-metal detectors. Plasmon-enhanced photodetection is achieved by properly optimizing Au interdigitated electrodes, micro-fabricated on Ge, a semiconductor that features a strong near IR absorption. Finite-difference time-domain simulations, photocurrent experiments and Fourier-transform IR spectroscopy are performed to validate how a relatively simple tuning of the contact geometry allows for an enhancement of the response of the device adapting it to the specific detection needs. A 2-fold gain factor in the Ge absorption characteristics is experimentally demonstrated at 1.4 µm, highlighting the potential of this approach for optoelectronic and sensing applications.

Hysteresis Behavior and Photoresponse Enhancement in Au Nanoparticle-Decorated Ge Photodetectors

“…where is the change in potential at the Au NPs/Ge interface and V n is the difference between the Fermi level and the conduction band minimum of the semiconductor (i.e., V n = 0.335 V for intrinsic Ge). We take to be 0.335 − 0.59 = −0.255 V because the barrier height at the Au/Ge interface is 0.59 V [25]- [27]. Pronounced band bending appeared below the Au NPs, and an approximately 200-nm-depth depletion region on the Ge side is observed.…”

Selective Area Epitaxy of GaAs/Ge/Si Nanomembranes: A Morphological Study

“…This is a typical procedure to reduce the threading dislocation density from 10 9 to 10 7 cm −2 [20]. Preferential etching techniques are used to estimate the threading dislocation density in the Ge thick film, using a solution of 10 mL HF (50% vol) + 15 mL HNO 3 (69% vol) + 1 mg KI + 1 mg I 2 + 5 mL CH 3 COOH (100%vol) + 60 mL H 2 O at 0 • C temperature for 30 s [21,22]. Counting statistics is performed on Ge etched surfaces imaged by atomic force microscopy (AFM).…”

Plasmon-assisted polarization-sensitive photodetection with tunable polarity for integrated silicon photonic communication systems

“…Thus, it has been demonstrated that redesigning electrodes as an optical antenna can enhance the sensitivity of a photodetector [12] and in the case of Ge, efficiently increase light absorption [11]. Further, well-designed plasmonic metal gratings offer the possibility of polarization-resolved photodetection [13,14]. However, from the application perspective both, detection performance and fabrication issues have to be considered.…”