Use of Mg diffusion in p-type Si to measure the residual P concentration by infrared absorption

Two possibilities for observing the infrared absorption of residual phosphorus in p-type silicon are discussed. Experimental results show that in p-type silicon the pairing of Mg, presumably with boron and/or oxygen, produces donor complexes with ionization energy less than that of phosphorus. The integrated intensity of the phosphorus lines of the sample after Mg diffusion indicates a phosphorus concentration of ∼ 1.5 × 1013 atoms/cm3.