The photoemissive process in the semiconducting alkali‐antimonides is examined and values are given for the band gaps and electron affinities. The high photoelectric efficiencies of these materials are attributed to the ability of the excited electrons to traverse relatively large distances (250 A) without overwhelming energy losses, rather than to negligibly small electron affinities. The efficiency is found to be strongly dependent on the percentage of the electrons which are excited into states above the vacuum level. The properties of these materials depend to a large extent on the crystal structure. Cs3Sb and Na2KSb have a cubic structure, are p type, and seem to have a relatively simple valence band structure. K3Sb and Na3Sb have hexagonal crystal structures, are n type, and seem to have a relatively complex valence band structure. The evidence for an effect of band bending on the photoemission is considered.

Photoemission and Related Properties of the Alkali‐Antimonides

Chapter 5 – the detection of scintillations

Conductivity measurements were made during the formation of alkali antimonides to deduce whether these materials are p‐type or n‐type conductors. Reproducible results were obtained, indicating that K3Sb and Na3Sb are n type while Cs3Sb and the multialkali antimonides are p type. A correlation between high‐quantum efficiency of photoemission and p‐type conduction is suggested.

n‐Type and p‐Type Conduction in Alkali‐Antimonide Photoemitters

Measurements of the intrinsic emittance and response time of a Cs3Sb photocathode are presented. The emittance is obtained with a solenoid scan technique using a high voltage dc photoemission gun. Photoemission response time is evaluated using a RF deflecting cavity synchronized to a picosecond laser pulse train. We find that Cs3Sb has both small mean transverse energy, 160 ± 10 meV at 532 nm laser wavelength, and a prompt response time (below the resolution of our measurement) making it a suitable material for high brightness electron photoinjectors.

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Thermal emittance and response time of a cesium antimonide photocathode

Es wird uber Messungen der optischen Absorption und der Temperaturabhangigkeit des Widerstandes von Caesium-Antimon-Schichten verschiedener Zusammensetzung berichtet. Die Absorptionsmessungen werden auf das auserhalb des lichtelektrischen Empfindlichkeitsbereichs liegende ultrarote Spektralgebiet ausgedehnt, um die Auslauferabsorption zu untersuchen. Die sich aus den Leitfahigkeits-Temperatur-Messungen an Schichten verschiedener Zusammensetzung ergebenden Aktivierungsenergien werden diskutiert. Die Absorption reiner Antimon- und Caesium-Schichten wird im Bereich von 400–1800 mμ gemessen.

Optische und elektrische Messungen an Caesium–Antimon‐Schichten verschiedener Zusammensetzung

Some Experimental Studies of the Conductivity and Thermo-electromotive Force of Cs3Sb Photo-Cathodes II

Magneto-Resistance of Cs 3 Sb Photo-Cathodes

Hall Effect in Cesium Antimonide with Audiofrequency Currents

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 ...

Toshimichi Sakata

Papers

Some Experimental Studies of the Conductivity and Thermo-electromotive Force of Cs3Sb Photo-Cathodes II

Magneto-Resistance of Cs 3 Sb Photo-Cathodes

Hall Effect in Cesium Antimonide with Audiofrequency Currents

Studies on the Cs3Sb Photo-Cathode

The Hall Effect in Cs3Sb Photo-Cathode