Island size effects in nanoparticle-enhanced photodetectors

Abstract

We report the effect of metal-island size variation in nanoparticle-enhanced photodetectors. Nanoparticle size was controlled by varying the deposition and annealing conditions used to produce the metal-island films. Increasing the size of silver-island particles fabricated onto 165 nm thick silicon-on-insulator (SOI) photodetectors resulted in a dramatic increase in the observed photocurrent. A nearly factor-of-20 photocurrent enhancement was observed for light of wavelength 800 nm, a significant improvement over previously reported results. The improvement is linked to two physical effects: the increased scattering efficiency of the larger nanoparticles and a qualitative change in the resonance characteristics of the metal-island film due to radiative coupling to the SOI waveguide modes.

Mechanism of plasmon-mediated enhancement of photovoltaic efficiency

“…Of particular interest are the recently reported experimental data on giant enhancement of photoluminescence and absorption of light by semiconductor surfaces (of photo-diodes) covered with metallic (gold, silver, or copper) nanospheres, with sphere radii of the order of several to several tens of nanometres [4,5,6,7,8,9]. These phenomena are recognized as promising for the enhancement of the efficiency of solar cells by the application of special metallic nanoparticle coverings of photo-active layers [4,5].…”

Plasmonic nanoparticle enhanced light absorption in GaAs solar cells

“…In recent years, plasmonic nanoparticles closely coupled to absorbing semiconductors have been utilized to enhance absorption in ultrathin film solar cells. [1][2][3][4][5] The antennalike nanoparticle response caused by dipole oscillation of localized surface plasmons serves to increase the material extinction for incident light owing to an enhanced local electromagnetic field near the nanoparticles at the surface plasmon resonance as well as an enhanced scattering cross section for offresonant light. From the perspective of photovoltaic conversion, plasmon resonant absorption represents an unwanted loss process, but off-resonant enhanced scattering can yield increases in absorption and photocurrent collection.…”

Plasmonic Rectenna for Efficient Conversion of Light into Electricity

“…However, in these recent metal-TiO2 Schottky diode structures [37][38][39][40][41][42][43][44][45][46][47], it would appear that the barrier layer was actually quite a bit thicker than 10 nm (probably in excess of 1 um) and further details was unable to be found in these papers. Semi-classical models did not account for non-equilibrium energy distributions of carriers, or do so through a localize lattice temperature.…”

“…Furthermore, different explanations have been presented about the role of metal nanoparticles in the observed improvement in light conversion efficiency. These include (i) metal nanoparticles increased absorption due to surface plasmons and light trapping effects [41], (ii) metal nanoparticles functioned as electron donor promoting electron transfer from metal to semiconductor [37,38,42] and (iii) metal nanoparticles served as electron trapping media that can minimize the surface charge recombination in semiconductor [43 , 44].…”

“…In 1998, Stuart et al [4] reported the first application of surface plasmons in the photovoltaic technology. It was found that the photocurrent of the thin-film Silicon-on-insulator (SOI) device was 18 times improved at the wavelength of 800 nm by metallic nanoparticles.…”