Papers by Author: Aurimas Uleckas

Abstract: The characteristics of the band-to-band Auger recombination in Czochralski-grown high resistivity Si and Ge single crystals have been studied using a contactless technique to measure excess carrier decay transients based on infrared absorption by free carriers. The measurements are performed using laser light excitation with wavelengths ranging from 1.2 to 2.5 µm to reduce inhomogeneity effects in the extraction of the Auger recombination parameters. A linear approximation of the initial excess carrier decay lifetime yields an approximate value of the Auger recombination coefficient in Ge γ_A,Ge ≈ 2×10^-31 cm⁶/s, which is close to that in Si. These characteristics also indicate that the difference in Auger recombination coefficients for the ehh and eeh processes is small. A more detailed fitting procedure applied simultaneously on a series of experimental transients yields a more accurate value of (8±3)×10^-31 cm⁶/s for the Auger recombination coefficient in Ge.

Abstract: Results are presented of a comparative study of diodes processed on n-type Cz grown Si substrates without and with Ge doping concentration of about 10¹⁹ cm^-3 and 10²⁰ cm^-3. In order to investigate thermal donor formation, isothermal annealing at 450°C for 0.5 – 5 h was carried out. As processed diodes were also irradiated with 2 MeV electrons with fluences in the range between 10¹⁴ and 10¹⁷ e/cm² to investigate the Ge doping influence on irradiation induced defect formation. Diodes after thermal and radiation treatments have been investigated by combining different techniques.