Physics of Internal Photoemission and Its Infrared Applications in the Low-Energy Limit

Figure 11

(a) Photovoltaic response measured by using different long-pass filters ( is the cut-on wavelength). A filter with m blocks the transport of photoexcited holes overcoming the graded-barrier region, thus suppressing both the short- and long-wavelength response. (b) Variation of photovoltaic response with the intensities of incident light (through adjusting the optical aperture size of the spectrometer), where 100% of light corresponds to the default aperture size. The calibration of responsivity takes into account the variation of light, which leads to nearly unchanged responsivity values for the <3 μm wavelength range. The >3.5 μm response becomes almost negligible when the intensity of incoming light is reduced to 2.9%.

(a)

(b)