Incorporation, Excitation and De-Excitation of Erbium in Crystal Silicon

Abstract

AbstractTemperature quenching of the 1.54 μm photoluminescence intensity and lifetime of Er in crystal Si was investigated between 12 K and 150 K. A p-type Czochralski-grown Si (100) wafer was doped with Er to a peak concentration of 5×1018 cm−3 using 1.5 MeV ion implantation. The Er doped layer was co-implanted with N to a peak concentration of 6×1019 N cm−3 The sample was annealed at 490 °C for 2 hours and at 600 °C for 1 hour. The 1.54 μm photoluminescence intensity shows a weak temperature quenching between 12 and 75 K, characterised by an activation energy of 1–10 meV. For temperatures above 75 K, a strong intensity quenching with an activation energy of 210 ± 10 meV is observed. The luminescence lifetime decreases from 420 μs at 12 K to 1 μs at 170 K, and shows strong quenching behaviour above 75 K, characterised by an activation energy of 135 ± 5 meV. The results are interpreted in terms of an impurity Auger energy transfer model. The lifetime quenching is attributed to a phonon assisted backtransfer process which becomes dominant at high temperatures. Intensity quenching is attributed to both the backtransfer process and a carrier de-trapping process which reduces the Er excitation rate. Spectral response measurements on Er implanted solar cells confirm the presence of a backtransfer process at room temperature.