GATABLE ULTRAFAST FIELD-ASSISTED PHOTOEMISSION TO LAMBDA=1.55 MU-M FROM IN0.5GA0.5AS HETEROSTRUCTURES

Field-assisted photoemission has been observed from a cesiated metal-s emiconductor structure with a fully depleted In0.5Ga0.5As absorption/e mission layer. The device showed photoemission at excitation wavelengt hs up to lambda=1.55 mu m, with an external quantum efficiency (QE)app roximate to 8x10(-5) at lambda=1.4 mu m. Large area Schottky contacts were made and the long-wavelength portion of the photoemissive respons e was electrically gatable with logic level voltages. A approximate to 14 ps device response time indicates significant potential for its us e in long-wavelength high-speed electron-optical imaging applications. (C) 1994 American Institute of Physics.