The anomalous avalanche breakdown

Abstract

Normally, the breakdown voltage of a p-n junction decreases with increasing doping density. But there are also cases in which the breakdown voltage increases with increasing doping density, e.g., for InSb in the doping range from 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">13</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> to 2 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">14</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> . The reason for the anomalous behavior is the saturation of the ionization coefficient with increasing electric field strength. The anomalous behavior can only be observed if the tunnel breakdown requires a higher field strength as the one required for saturation of the ionization coefficient. This paper presents a rather simple theory yielding analytical solutions for the normal and anomalous avalanche breakdown. Treated is the influence of the doping profile upon the breakdown voltage in plane junctions and the influence of the radius of curvature for cylindrical one-sided abrupt junctions. The influence of the temperature upon the breakdown voltage and the multiplication factor as function of voltage is calculated for one-sided abrupt plane junctions. Finally, the temperature and doping range for the anomalous avalanche breakdown and the transition region is plotted for the semiconductors InSb, InAs, CdHgTe, PbSnTe, Ge, Si, GaAs, and GaP.