Low-Temperature Diffusion of Transition Metals at the Presence of Radiation Defects in Silicon

摘要

Low-temperature diffusion of Cr, Mo, Ni, Pd, Pt, and V in silicon diodes is compared in the range 450 - 800 ℃. Before the diffusion, the diodes were implanted with high-energy He~(2+) to assess, if the radiation defects enhance the concentration of metal atoms at electrically active sites and what is the application potential for carrier lifetime control. The devices were characterized using AES, XPS, DLTS, OCVD carrier lifetime and diode electrical parameters. The metal atoms are divided into two groups. The Pt, Pd and V form deep levels in increased extent at the presence of radiation defects above 600 ℃, which reduces the excess carrier lifetime. It is shown as a special case that the co-diffusion of Ni and V from a NiV surface layer results fully in the concentration enhancement of the V atoms. The enhancement of the acceptor level V~(-/0) (Ec - 0.203 eV) and donor level V_(0/+) (Ec - 0.442 eV) resembles the behavior of substitutional Pt_s. The second group is represented by the Mo and Cr. They easily form oxides, which can make their diffusion into a bulk more difficult or impossible. Only a slight enhancement of the Cr-related deep levels by the radiation defects has been found above 700 ℃.