A new variation of the deep level transient spectroscopy technique is presented. In the new approach, the current transient is integrated, yielding a charge transient. A simple circuit for integrating the current is given and is analyzed. The charge transient technique is compared to previous capacitance transient and current transient techniques, and the advantages of the new method are discussed. The effects of diode leakage currents are also analyzed. Data are presented for defects in neutron irradiated Si.

Uniaxial stress has been used with transient spectroscopy to study the level at E c -0.17 eV in neutron-irradiated silicon. The defect symmetry, observed stress-induced electronic redistribution, and preferential stress-induced defect orientation have been determined and the reorientation activation energy has been measured. All of these effects are consistent with the A center.

Oxygen-related thermal donor formation in Czochralski silicon is characterized by the capacitance-voltage and deep level transient spectroscopy techniques as a function of 450 °C anneal time following hydrogenation. Increases in the formation rate and number of thermal donor (TD) defects found after hydrogenation are reported. This study finds an increase in TD+/++ concentration in the near-surface region at short anneal times, but at longer times an elevated concentration was not observed. No acceleration through the sequence of thermal donor defects was detected. This fails to support the model of hydrogen lowering the barrier to oxygen diffusion and accelerating the TDn→TDn+1 transitions. This study does, however, support a model in which the hydrogen increases the available thermal donor core sites.

A deep level transient spectroscopy (DLTS) study of 450 °C annealed Czochralski silicon is presented. Particular attention is given to the relative concentrations of the two thermal donor energy levels Ec−0.15 eV and Ec−0.07 eV. Relative concentrations of the Ec−0.15 eV and Ec−0.07 eV energy levels indicate that there are fewer of the more shallow level. Also there is anomalous motion of the energy levels with anneal time indicating the gradual accretion of the thermal donor complexes. The suggested correlation with infrared absorption (IR) studies is that the nine double-donor defects found by IR form sequentially in the material and the DLTS energy level obtained merely reflects the most abundant of the nine distinct complexes. This indicates that the nine thermal donors are formed by the addition of some constituent to an earlier complex. As the thermal donor complex accretes the associated energy levels change, moving to shallower energies as anneal time increases. These findings tend to contradict the simple thermal donor models.

Several superlattice structures, grown by molecular beam epitaxy, have been used to reduce the density of threading dislocations originating from the GaAs substrate. Results clearly indicate that compared to epitaxial layers grown directly on GaAs substrates, a GaAs-InxGa1−xAs superlattice (x<0.12) reduces the dislocations by approximately two orders of magnitude. Transmission electron microscopy, electron beam induced current, and etch pit density have been used to characterize the effectiveness of using superlattice buffer layers for the reduction of defects in GaAs epilayers.