FIELD-ASSISTED SEMICONDUCTOR PHOTOCATHODES FOR STREAK TUBES

Field-assisted semiconductor photocathodes (PCs) based on In0.53Ga0.47 As/InP heterostructures with a Schottky barrier for the spectral range of 1.0 to 1.7 mu m are investigated. A technique is presented for man ufacturing PCs. The method for ultrahigh vacuum transfer of the PC int o vacuum devices is discussed. It is shown that the sensitivity of a P C in a sealed-out device at lambda = 1.55 mu m is two to three orders of magnitude higher compared to traditional Ag-Cs-O PCs, acid approach es 400 mu A/W at lambda = 1.6 mu m for PCs with Schottky barriers of A u film. It is shown that PCs With Schottky Au barriers can be activate d with Cs only and without O, and the stability is considerably better than with a Ag barrier. A strong decrease of the internal photoeffect is discovered in the case when the PC is illuminated from the metalli c film side. The developed PCs can be used for time analyzing tubes to record picosecond pulses with milliwatt peak intensity. (C) 1998 Soci ety of Photo-Optical Instrumentation Engineers.