Measurement and modeling of the anomalous dynamic response of high resistivity diodes at cryogenic temperatures

A negative dynamic conductance and a negative dynamic capacitance were observed when a high resistivity (10 k Ohm cm) silicon p/i/n diode is based in the double injection regime at liquid helium temperatures. At high frequencies (above 100 kHz) the negative capacitance varies as 1/omega(2) while the negative conductance exhibits a more complex behavior and, eventually changes sign at even higher frequencies (1 MHz). A quantitative model is presented which accounts for the conductance and capacitance behavior as a function of frequency and bias. The model is based on the shallow donor impact ionization and carrier trapping at the ionized donors. Additionally the breakdown voltage of the static I-V characteristics is used to calculate the unintentional compensation in the high resistivity substrate. (C) 1997 Elsevier Science Ltd.