Electronic properties of palladium doped silicon

Abstract

The concentrations of active palladium for different diffusion temperatures were measured. It is shown that the concentration of PdI is x 10¹⁵ and 3 x 10¹⁴ cm⁻³ at 1200 and 900°C respectively. The concentration of PdII is shown to be lower than PdII.

The capture probabilities for each of the levels were also determined by using the photoconductivity decay method. It is shown that the donor level is the dominant recombination level, with electron and hole capture constants of 3.4 x 10⁻⁸ cm³/sec and 2.2 x 10⁻⁹ cm³/sec respectively. These values, coupled with the data on solid solubility, indicate that palladium can be used for high temperature deep diffusions where the minority carrier lifetime must be reduced to the 0.5 μsec range.

A study is undertaken to determine the electronic properties of palladium in silicon as a possible substitute for gold in controlling minority carrier lifetime. Hall effect measurements have shown that electrically active palladium exist in silicon in the form of two independent species. The first, designated PdI, is amphoteric and exhibits an acceptor level at 0.22 ± 0.01 eV below the conduction band edge as well as a donor level at 0.33 ± 0.01 eV above the valence band edge. The second specie, designated PdII, exhibits an acceptor level at 0.32 ± 0.01 eV above the valence band edge.