Abstract: In this paper,the.trapping effect of the shallow impurity energy level in silicon at low temperatures is analyzed. The expression for the ratios of the injected electrons in the conduction band to the total electrons n_C/n_T at various injection levels in p-type silicon is given. The main. results indicate that the trapping effect of the shallow impurity energy level under the low injection condition will exert a tremendous influence on the frequency properties of bipolar devices at low temperatures, and it becomes neligible at the high injection level because the total injected electrons overwhelm the carrier trapping effect.

Key words: Trapping, Silicon, Low Temperature, Shallow Impurity Energy Level