A STUDY OF DRIFT MOBILITY IN NEUTRON IRRADIATED n-TYPE GERMANIUM

Technical Report · Sun Jan 01 04:00:00 EST 1961

OSTI ID:4038763

Closser, W H

A description is given of the results of a -drift-mobility experiment on n-type germanium which was bombarded with high-energy particles, and a model is postulated which tentatively explains the results for the case of neutron bombardment. The results show that the drift mobility increases for low values of neutron flux, and then decreases very rapidly, approaching zero as the sample is driven intrinsic by the radiation. The observed mobility increase was large enough to be removed from the reaim of experimental error, and was found to be repeatable. The results of the drift-mobility experiment on electron-irradiated material show that the mobility decreases with increased irradiation, and that the decrease is similar to that observed for neutron irradiations. The electrons are known to introduce point defects, which led to the development of the proposed model. A mathematical analysis showed that the mobility increase in neutron-irradiated material cannot be explained in terms of theoretical models which picture the neutron damage site as a charged scattering center, or as a group of such centers. Further mathematical analyses show that a variable mobility, which can be postulated for neutron damage, cannot explain the results either. From other experimental work it was known that Frenkel-type defects did exist in neutron-irradiated germanium, and with some evidence supporting the Gossick model. A model was proposed to explain the experimental results, which combines the Gossick-void mcdel and the point-defect mcdel, and says that the neutron damage site is not one or the other, but instead looks like a combination of both as far as the electrical properties of the material are concerned. The void fraction caused by the neutrons is calculated using flux measurements. The number of point defect-associated scattering centers introduced per incident neutron, as calculated from the model using the necessary refinements, is found to be seven for the case of the Omega West irradiations. Although the model is very crude and qualitative, it is believed to have some merit as an interim means of explaining neutron damage in n-type germanium. (auth)

• Research Organization: Sandia Corp., Albuquerque, N. Mex.
• NSA Number: NSA-15-022794
• OSTI ID: 4038763
• Report Number(s): TID-12881; SCDC-2313
• Country of Publication: United States
• Language: English

Related Subjects

CRYSTALS
DEFECTS
DISTRIBUTION
ELECTRIC CHARGES
ELECTRON BEAMS
FRENKEL DEFECTS
GERMANIUM
IRRADIATION
LATTICES
MATHEMATICS
METALS, CERAMICS, AND OTHER MATERIALS
MOBILITY
MOTION
NEUTRON BEAMS
NEUTRON FLUX
RADIATION EFFECTS
SCATTERING
SEMICONDUCTORS
VELOCITY
VOIDS