Room temperature photoemission up to a wavelength threshold of 2.3 µm from n+-InAs0.4P0.6/p−-InAs0.4P0.6/p−-ln0.7Ga0.3As field-assisted photocathode

Room temperature photoemission up to a long-wavelength threshold of 2.3 mu m was obtained from an n(+)-InAs0.4P0.6/p(-)-InAs0.4P0.6/p(-)-In0.7Ga0.3As field-assisted photocathode. The quantum efficiency at 2.1 mu m is 2.47 x 10(-1)%. The results show that the field-assisted photocathode with its pn junction is suitable not only for achieving high quantum efficiency performance but also for extension of the long infrared threshold wavelength. The temperature dependences of both the quantum efficiency and the dark current for the photocathode are also presented. (C) 2014 The Japan Society of Applied Physics