Studies on. the Cs3Sb Photo-Cathode

Spectral and energy distributions for external photoelectrons ejected from Cs 3 Sb photo-cathodes were determined by the method of interchangeable emitters. Precautions were taken to secure electrically uniform surfaces. The energy distribution had an usual form for h ν=2.14, 2.27, 2.84, 3.06, 3.39 and 3.96 ev. The results indicated that Cs 3 Sb were semiconductors with a small values of δ=0.2∼0.3 ev. Here δ is the energy difference between the Fermi level and the top of the occupied band of energy states. The photoelectric work function (ϕ') was found about 1.8±0.1 ev. The work function obtained from the contact potential techniques were about 1.5∼1.6 ev. On the other hand, the thermionic work function was found about 1.3∼1.5 ev, using Richardson's formula. Typical values of m 1)2) [parameter depending both on the form of occupied band arid on the energy dependence of the photo-electric excitation probability] obtained both from energy and spectral measurements were 1. Thermoelectric measurements showed that all samples were P type.