Papers by Author: Jan Vanhellemont

Abstract: Further experimental support for the A_Si-Si_i-defect as cause of light-induced degradation and as the defect responsible for a photoluminescence peak called P line in indium doped silicon is given. The A_Si-Si_i-defect model has two main implications related to oxygen clustering during Czochralski crystal growth and the common understanding of the boron interstitial defect. These implications are discussed and it is shown that the A_Si-Si_i-defect model is in agreement with available experimental data related to oxygen clustering and the boron interstitial defect.

Abstract: For the development of the crystal pulling process for 450 mm-diameter defect-free Si crystals, the impact of thermal stress on intrinsic point defect behavior during crystal growth is studied using extensive density functional theory calculations. The impact of thermal stress on the so-called Voronkov criterion and on void formation is clarified and compared with published experimental results.

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.