Browsing by Author "Pearton, SJ"

Now showing 1 - 7 of 7
  • Thumbnail Image
    Item
    Deep level transient spectroscopy of n-GaAs surface barrier diodes for nuclear radiation detection
    (Australian Atomic Energy Commission, 1981-01) Pearton, SJ; Alexiev, D; Tavendale, AJ; Williams, AA
    Deep level transient spectroscopy has been applied for the first time to the study of deep level defects in n-GaAs nuclear radiation detectors. Devices made from commercial bulk and epitaxial material with net donor impurity densities in the range 5 x 10 13 -3 x 10 16 cm -3 have been studied and several common levels observed. The Poole-Frenkel effect has been identified in three levels (Ev + 0.19 eV, Ec - 0.62 eV Ec - 0.73 eV) in the epitaxial GaAs. A value for the Poole-Frenkel constant of β = 4.7 ≥ 1.4 x 10-4 eV V-½ cm½ was obtained compared to the theoretical value for GaAs of 2.3 x 10-4 eV V-½ cm½.
  • Thumbnail Image
    Item
    Deep level transient spectroscopy of y-ray induced defects in germanium
    (Australian Atomic Energy Commission, 1980-12) Pearton, SJ; Williams, AA; Tavendale, AJ
    Deep level transient capacitance spectroscopy has been used to examine γ-ray induced defect centres in germanium crystals grown under widely varying conditions. A deep acceptor level at Eν + 0.38 eν has been observed for the first time in all p-type samples; this was removed by annealing at 675 deg C for three hours. A new deep donor level at Eс - 0.42 eν observed in n-type material was not removed by this procedure.
  • Thumbnail Image
    Item
    Hydrogenation of deep-level hole-trapping centres associated with grain boundaries in germanium.
    (Australian Atomic Energy Commission, 1983-04) Tavendale, AJ; Pearton, SJ
    Effects of the hydrogenation of deep level, hole-trapping centres associated with grain boundaries incorporated in diodes from n- and p- type germanium have been examined by deep level transient capacitance spectroscopy and measurement of reverse bias leakage current. Significant reductions in diode leakage current (by factors of 2 to 10 at 77 K) and suppression of deep level centres were observed following exposure to a low pressure (0.5 torr), radio-frequency-induced hydrogen plasma at 300oC for 2 hours; no reversal was observed after a subsequent vacuum anneal at the same temperature and time.
  • Thumbnail Image
    Item
    The nature of the Ev + 0.23 eV and Ev + 0.38 eV gamma-induced centres in Ge.
    (Australian Atomic Energy Commission, 1982) Pearton, SJ; Tavendale, AJ
    All p-type Ge grown by the Czochralski technique from silica crucibles under an H sub 2 atmosphere shows two dominant acceptor defects on gamma irradiation. Measurements by DLTS are reported which support the hypothesis that these centres (E(v) + 0.23 eV E(v) + 0.38 eV) are most likely due to complexes between oxygen and lattice vacancies.
  • Thumbnail Image
    Item
    Neutralisation of point defects in Ge and GaAs by hydrogen incorporation.
    (Australian Atomic Energy Commission, 1981-10) Pearton, SJ
    Deep level transient spectroscopy has been used to observe the passivation of copper-related centres in Ge, y-radiation induced centres in Ge and residual defects in GaAs by reaction with atomic hydrogen. Data are presented on the efficiency of passivation as a function of the duration and temperature of the exposure to hydrogen. A 3-hour exposure in a H plasma at 300oC passivated >90% of the copper centres in Ge to a depth of ~80 μm; 3 hours at 250oC passivated 3 x 1015 donor defects cm-3 to a depth of ~1.1 μm in GaAs. An estimate of 3.5 x 10-9 cm2 s-1 at 300oC was obtained for the diffusion coefficient of H in Ge; at 225oC the corresponding number for GaAs is estimated to be ~3 x 10-13 cm2 s-1.
  • Thumbnail Image
    Item
    Transient capacitance measurements of deep level defects introduced in y-ray compensated germanium by long-term annealing at room temperature
    (Australian Atomic Energy Commission, 1980-09) Pearton, SJ; Williams, AA; Tavendale, AJ; Lawson, EM
    Deep level transient spectroscopy (DLTS) has been applied to defect centres in γ-ray compensated germanium that has been subjected to long-term annealing at room temperature. Deep donor levels (Ec - 0.36 eV Ec - 0.20 eV) have been observed for the first time; annealing at 675ºC for 3 hours increased their concentration in proportion to the free carrier density indicating stable defect-impurity complexes. Recently irradiated samples from the original material have not shown these levels. The results support Russian work on the compensation mechanism - the formation of electically inactive vacancy-donor complexes.
  • Thumbnail Image
    Item
    Transient conductance spectroscopy measurements of defect states in y-irradiated n-channel silicon field effect transistors with possible y-dosemeter applications
    (Australian Atomic Energy Commission, 1980-12) Pearton, SJ; Tavendale, AJ; Williams, AA
    A deep level transient capacitance spectroscopy (DLTS) system modified for the measurement of transient conductance has been used to observe gamma-ray induced defect centres in the gate junction of 2N4416 Si field effect transistors. The defect concentrations increased linearly wth gamma-dose in the range 50 kGy to 10 x 10 3 kGy (5-1000 Mrad) for the common E(c) - 0.17 eV level and in the range 500 kGy to 10 x 10 3 kGy (50- 1000 Mrad) for the levels E(c) - 0.22 eV and E(c) - 0.44 eV. Another common level a hole trap at E(v) + 0.42 eV was the only minority trap observed. The technique may be useful for measuring gamma-fluxes in situations inaccessible to standard dosemeters (e.g. flux-mapping).