Formation of defect complexes by electron-irradiation of hydrogenated crystalline silicon

We studied properties of complexes responsible for the optical-absorption peaks at about 1870 and 2072 cm(-1) which were formed by room-temperature electron-irradiation of hydrogenated Si. Specimens were n-type, p-type, and high-purity Si crystals. They were doped with hydrogen (H) and/or deuterium (D) by annealing at 1300 degreesC in H-2 and/or D-2 gas followed by quenching. They were then irradiated with 3-MV electrons at room temperature. We measured their optical-absorption spectra by a Fourier transform IR spectrometer at about 7. K. The 1870-cm(-1) peak was weak in B-doped specimens and strong in high-purity and P-doped specimens. On the other hand, the 2072-cm(-1) peak was weak in P-doped specimens and strong in high-purity and B-doped specimens. These results support the hypothesis that the 1870- and 2072-cm(-1) peaks are due to complexes which include I (self-interstitial) and H and V (vacancy) and II, respectively. The intensities of both the 1870- and 2072-cm(-1) peaks were proportional to the square of electron dose at low doses, which indicates that they are due to I2H2, and V2H2, respectively. In an isochronal annealing experiment, the 1870- and 2072-cm(-1) peaks disappeared after annealing below 200 degreesC and 300 degreesC, respectively.