Electronic properties and dopant pairing behavior of manganese in boron-doped silicon

Abstract

Boron-doped silicon wafers implanted with low doses of manganese have been analyzed by means of deep-level transient spectroscopy (DLTS), injection-dependent lifetime spectroscopy, and temperature-dependent lifetime spectroscopy. While DLTS measurements allow the defect levels and majority carrier capture cross sections to be determined, the lifetime spectroscopy techniques allow analysis of the dominant recombination levels and the corresponding ratios of the capture cross sections. Interstitial manganese and manganese-boron pairs were found to coexist, and their defect parameters have been investigated. In good agreement with the literature, this study identifies the defect level of manganese-boron pairs to be located in the lower half of the band gap at an energy level of Ev+0.55 eV with a majority carrier capture cross section of σp=3.5×10−13 cm2. The capture cross-section ratio was found to be k=σn∕σp=6.0. This implies that the previously unknown minority carrier capture cross section is σn=2.1×1012 cm2. Concerning the defect related to interstitial manganese, this study identifies the most recombination-active level to be located in the upper half of the band gap at EC−0.45 eV with a corresponding ratio of the capture cross sections of k=9.4. In addition, the temperature-dependent association time constant of manganese-boron pairs is determined to be τassoc,Mn=8.3×105 K−1 cm−3(T∕Ndop)exp(0.67 eV∕kBT) and found to differ from that for iron by a factor of 3 at room temperature, allowing this association time constant to be used as a fingerprint for a possible contamination with manganese. Also, the diffusion coefficient of interstitial manganese in silicon is determined from these experiments in a temperature range from 70 to 120 °C. It can be represented by the expression DMn=6.9×10−4 cm2 s−1 exp(−0.67 eV∕kBT).