Accession Number : AD0612520

Title :   PHOTOCAPACITANCE EFFECTS IN ADDITIVELY COLORED ALKALI HALIDE CRYSTALS,

Corporate Author : MARTIN CO BALTIMORE MD RESEARCH INST FOR ADVANCED STUDIES

Personal Author(s) : Kahn,D. ; Glass,A. J.

Report Date : 10 MAR 1960

Pagination or Media Count : 10

Abstract : Additively colored alkali halide crystals were placed between current blocking electrodes and an increase in the capacitance and conductance of the crystal was found on illumination. A measurement of these quantities at frequencies between 2 and 1000 c/s has shown that the observed behavior follows quite closely a linearized theory developed by J. Ross MacDonald. The region of application of the theory was examined experimentally, and results show that the theory may be used for larger applied voltages than assumed in the theory. An analysis of the experimental data indicates that the field induced electrode breakdown for the larger voltages (approx. 5 V r.m.s.) is of such a nature that the equivalent circuit describing the crystal continues to be valid. This has also been observed by others. Using the results of the theory the mobility of KI and KBr crystals at room temperature was measured. These determinations agree substantially with measurements by others using Hall effect methods. Measurements at low frequencies revealed phenomena due to the finite recombination rate of the conduction electrons and ionized F-centers. From an analysis of this behavior, the capture cross section of an ionized F-center in KBr was determined. The recombination rate constant in KBr was also measured. (Author)

Descriptors :   (*PHOTOELECTRIC EFFECT, ALKALI METAL COMPOUNDS), (*ALKALI METAL COMPOUNDS, HALIDES), (*POTASSIUM COMPOUNDS, HALIDES), (*COLOR CENTERS, PHOTOELECTRIC EFFECT), CRYSTALS, CAPACITANCE, ELECTRICAL CONDUCTIVITY, IODIDES, BROMIDES, IONIZATION, RECOMBINATION REACTIONS, CIRCUITS

Distribution Statement : APPROVED FOR PUBLIC RELEASE