Effect of anisotropic electron momentum distribution of surface plasmon on internal photoemission of a Schottky hot carrier device.

We recently reported that an Au/TiO₂ photonic crystal device for photochemical energy conversion showed a sub-bandgap photoresponse centered at the surface plasmon polariton (SPP) resonant wavelength of this device. Here we developed a theoretical modeling of the internal photoemission in this device by incorporating the effects of anisotropic hot electron momentum distribution caused by SPP. The influences of interband and intraband transition, anisotropic momentum distribution of hot electrons by SPP are integrated to model the internal quantum efficiency (IQE) of this device. Near resonant wavelength, SPP dominates the electric field in the thin Au layer, which generates hot electrons with high enough momentum preferentially normal to the Schottky interface. Compared with the widely used Fowler's theory of internal photoemission, our model better predicts hot electron collection in Schottky devices. This model will provide a design guidance for tuning and enhancing photoresponse of Schottky hot carrier devices.