Fig. 2
From: Quantifying the role of surface plasmon excitation and hot carrier transport in plasmonic devices
Role of plasmon excitation on hot electron IPE in metal–semiconductor heterostructures. a Schematic representation of the designed plasmonic heterostructures as well as measurement configuration: a 20 nm thick, nano-patterned gold (Au) photoelectrode is fabricated on n-type GaN (3.4 eV band gap, Schottky barrier ΦB ~1.2 eV) together with a 75 nm thick titanium (Ti) Ohmic contact; light is incident on the plasmonic resonant Au nanostripe array (stripe width W, array period P from the bottom and the photocurrent is collected via two microcontact probes); b short-circuit photocurrent Isc (i.e., 0 V applied bias) upon illumination of one heterostructure (W = 61 nm) with a diode laser (λlaser = 633 nm) as a function of incident power; c EQE spectrum of the fabricated heterostructure with stripe width W = 61 nm and periodicity P = 230 nm exhibiting a resonance peak at λpeak = 650 nm; d spatial maps of absorption for illumination of the Au photoelectrode off-resonance (514 nm–2.14 eV) and on-resonance (650 nm–1.9 eV) with light polarized perpendicular to the stripes; e measured (solid line) and simulated (dashed line) absorption spectra for the same heterostructure exhibiting a plasmon resonance at λpeak = 650 nm; f EQE and absorption resonance peak wavelengths (λpeak) for three heterostructures with constant array periodicity (P = 230 nm) and increasing nanostripe width, W, equal to 61 nm (blue), 70 nm (gray), and 85 nm (red), respectively. Representative SEM micrographs are shown on the right (scale bar = 500 nm); g IQE spectra of the three plasmonic heterostructures shown in part (f)
