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. A t high frequencies (above 100 kHz) the negative capacitance varies as 1/omega(2) while the negative conductance exhibits a more complex beha vior and, eventually changes sign at even higher frequencies (1 MHz). A quantitative model is presented which accounts for the conductance a nd 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 stati c I-V characteristics is used to calculate the unintentional compensat ion in the high resistivity substrate. (C) 1997 Elsevier Science Ltd.