PHOTOCURRENT, SPACE-CHARGE BUILD-UP AND FIELD EMISSION IN ALKALI HALIDE CRYSTALS
MASSACHUSETTS INST OF TECH CAMBRIDGE LAB FOR INSULATION RESEARCH
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Research is discussed on the formation of space charges, the re lease of electrons from the cathode, and their transconductance through a dielectric. The considerations are based on additively colored alkali halide crystals which represent a transparent solid with frozen-in-electrons that can be mobilized by light absorption. When these electrons move toward the anode, they leave a positive space charge an adjustable cathode fall results which can be steepened until electrons are released by field emission. The steady-state and transient solutions for the charging and discharging cycle were calculated. The effects of light intensity, wave length, and field emission are discussed. KBr crystals were investigated experimentally as a function of time, voltage, light intensity, and color-center density. Field emission was produced with voltages as low as 1 v, and a field-emission photocell was realized.
- Atomic and Molecular Physics and Spectroscopy