Thin Au surface plasmon waveguide Schottky detectors on p-Si

Abstract

Surface plasmon sub-bandgap Schottky detectors based on an asymmetric Au stripe waveguide on p-Si are investigated theoretically and experimentally at free-space wavelengths of λ(0) = 1310 and 1550 nm. Au on p-Si produces a low Schottky barrier (0.33 eV), which improves the internal quantum efficiency. Thick and thin Au stripes are compared, with the latter increasing the hot hole emission probability relative to the former, and thus also improving the internal quantum efficiency. Two excitation schemes are considered: end facet illumination which launches surface plasmons on the detector, and top illumination which does not. Both schemes are implemented using a piezoelectric positioner that is programmed to scan the detection area in steps of 100-200 nm, thus enabling the acquisition of high-resolution photocurrent maps. The surface plasmon detectors yield a responsivity of ~1 mA W(-1), ~2× larger than the same detectors under top illumination, due to the absorption of surface plasmons. We compare the measurements with theoretical results for both excitation schemes and estimate the hot hole attenuation length in our Au stripes to be ~23 nm.

All-Si photodetector for telecommunication wavelength based on subwavelength grating structure and critical coupling

“…Though, this model is rigorously valid at cryogenic temperature, it has been shown experimentally that it can predict the efficiency of the IPE-based PD at room temperature with relatively good accuracy. 24,25 Based on this model, 12 where P(E) is the probability of carriers with the energy of E overcoming the Schottky barrier φ B . According to this model, if the silicide layer thickness t m is much smaller than the carrier scattering length l h (t m l h ), the carriers experience a number of reflections from the metal boundaries.…”

Surface Plasmon Enhanced Schottky Detectors

“…Detectors where the Schottky metal contact is also a metal stripe waveguide [2], have been proposed on n-Si and on p-Si in symmetric [41,46] and asymmetric [40,42,43,50,52] cladding configurations. Figure 9.5a gives a sketch of an asymmetric SPP waveguide detector consisting of a thin narrow metal stripe on Si with air on top [42].…”

“…Figure 9.5c shows a measured photocurrent map of a Au on p-Si detector, generated by scanning a tapered PM-SMF over the end facet (following Fig. 9.5a) using a piezoelectric nanopositioner [50]. The Au stripe width and thickness in this case were 1.5 μm and 40 nm, the reverse bias was 100 mV, the incident optical power was 1 mW, and the excitation wavelength was 1310 nm.…”

“…The Au stripe width and thickness were 2.5 μm and 135 nm, the reverse bias was 200 mV and the incident optical power was 2 mW. c (Adapted from [50]. Copyright (2012) by the Institute of Physics.)…”

Surface plasmon enhanced optoelectronics

“…SPP waveguide photodetectors have been reported based on absorption in organic [18] or semiconductor [19] materials. Asymmetric metal stripes supporting SPPs confined along the thickness and width of the stripe [20] have been used as SPP waveguide photodetectors [21][22][23][24][25]. The photodetectors were created as Al or Au stripes on n-type or p-type Si simultaneously forming a Schottky contact.…”