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Surface passivation for ultrathin Al 2 O 3 layers grown at low temperature by thermal atomic layer deposition
Author(s) -
Frascaroli J.,
Seguini G.,
Cianci E.,
Saynova D.,
van Roosmalen J.,
Perego M.
Publication year - 2013
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201200568
Subject(s) - passivation , materials science , atomic layer deposition , annealing (glass) , silicon , analytical chemistry (journal) , thermal oxidation , deposition (geology) , atmospheric temperature range , oxide , forming gas , thin film , layer (electronics) , optoelectronics , nanotechnology , chemistry , composite material , metallurgy , biology , meteorology , paleontology , physics , chromatography , sediment
Thin layers of Al 2 O 3 with thickness t ox ≤ 8 nm were grown by thermal atomic layer deposition at low temperature of 100 °C and applied to achieve functional surface passivation of crystalline silicon substrates. Measurements of the effective lifetime were performed to characterize the surface passivation effect. Lifetime values in the range of 0.5 ms were obtained for Al 2 O 3 films with t ox ≥ 6 nm upon post‐deposition annealing (PDA) at 250 °C in N 2 atmosphere. However, when the thickness of the Al 2 O 3 films was reduced to 4 nm, lifetime values well below 0.1 ms were observed even after PDA. Combined capacitance–voltage and conductance–voltage measurements were carried out to extract the amount of charges located near the silicon‐oxide interface and the density of electrically active interface states, respectively. The results of the electrical characterization were used to elucidate the intimate physical mechanisms that govern charge recombination at the Al 2 O 3 /Si interface. Density of interface states (a) and lifetime (b) values are reported as a function of the PDA temperature for Al 2 O 3 films of three different thickness values: 4, 6, and 8 nm.