Recombination of Mobile Carriers Across Boron Excited Levels in Silicon at Low Temperatures

Abstract

Carrier recombination through shallow boron-impurity centers in doped weakly compensated silicon is studied. Much attention is paid to theoretical explanation of the “empirical” temperature dependences of the carrier lifetime τ(T) in the temperature range of (1.7–4.2) K at the doping level n_B ≥ 10¹⁴ cm^–3 and compensation ≤10% (n_d + n_a ≤ 10¹³ cm^–3. It is possible to rather accurately determine that the shallow excited level with a binding energy of 5 meV (3s-state) is quasi-resonant. Approximate formulas for the trapping efficiency are obtained. The effect of “weak” magnetic field (10²–10³) G on the capture coefficient is studied; it is shown that the “weak” magnetic field slightly reduces the lifetime of carriers, thus stimulating their recombination.