Central Technological Library of the University of Ljubljana (CTK)
13.
Activation of the ▫$Na_2KSb$▫ photocathode with Cs and ▫$O_2$▫ at lowered temperatures
Erjavec, Bojan
Several attempts to activate the ▫$Na_2KSb$▫ photocathode with Cs and ▫$O_2$▫ at RT failed due to the growth of a thick intermediate oxide layer, consisting of Sb, na and K oxides, and thus to the ...formation of a highly alkali-deficient ▫$Na+2KSb$▫ base layer. The spectral sensitivities in the near IR region were very low because these defects had contributed to a reduced escape depth of excited electrons and an increased photoelectric threshold energy. A novel activation at 140 K has therefore been performed in order to promote the adsorption of Cs and to prevent the harmful diffusion of O into the near-surface region of the ▫$Na_2KSb$▫ and the strong diffusion of K from the interior of the ▫$Na_2KSb$▫ towards its surface. During cooling-down from RT to 140 K, the photosensitivity of the ▫$Na_2KSb$▫ dropped to oabout one third of the initial value measured at RT, due to an increase in the electrical resistivity of the ▫$Na_2KSb$▫, thus causing a space charge to arise, which attenuated photoemission. The ▫$Cs-O_2$▫ cycles resulted in a relatively high photosensitivity of ▫$250 \mu A/lm$▫, if its initial drop is taken into account. During heating to RT, the photosensitivity first increased to ▫$370 \mu A/lm$▫ at about 210 K, and then, in the range between 210 K and RT, it unexpectedly decreased from 370 to ▫$100 \mu A/lm$▫. This behaviour was attributed to defects which caused the build-up of a surface potential barrier, such as the reduction of Cs (sub)ocides, which was enabled by the enhanced diffusion of K from the interior of the ▫$Na_2KSb$▫ into the deposited Cs,O surface film at temperature above 210 K.
It was not necessary to add the material to the shelf.
Bibliographic material was successfully added on shelf.
Adding bibliographical material on shelf was not successful.
Material is already on the shelf.
Permalink
URL:
Impact factor
Access to the JCR database is permitted only to users from Slovenia. Your current IP address is not on the list of IP addresses with access permission, and authentication with the relevant AAI accout is required.
Year
Impact factor
Edition
Category
Classification
JCR
SNIP
JCR
SNIP
JCR
SNIP
JCR
SNIP
Select the library membership card:
DRS,
in which the journal is indexed
Database name
Field
Year
Links to authors' personal bibliographies
Links to information on researchers in the SICRIS system
Subject headings in COBISS General List of Subject Headings
Select pickup location
The material from the parent unit is free. If the material is delivered to the pickup location from another unit, the library may charge you for this service.
