Papers by Keyword: Poole-Frenkel Effect

Abstract: Shallow dislocation-related electronic states near the bottom of the conduction band in n-type Si bonded sample have been investigated with deep-level transient spectroscopy (DLTS), isothermal transient spectroscopy (ITS) and energy-resolved DLTS. The effect of thermoemission (TE) enhancement in external electric field was found and the dependence of the TE activation energy reduction as a function of the filling grade was obtained for these states. A new model of dislocation-strain-related Poole-Frenkel effect that accounts for the own electric field of internal charge of dislocation line is suggested and compared with the experimental data.

Abstract: Deep Level Transient Spectroscopy (DLTS) and Double-correlated DLTS (DDLTS) measurements have been conducted on Schottky contacts fabricated on n-type 4H-SiC epilayers using different contact metals in order to separate the EH₆- and EH₇-centers, which usually appear as a broad double peak in DLTS spectra. The activation energy of EH₆ (E_C - E_T(EH₆) = 1.203 eV) turns out to be independent of the electric field. As a consequence, EH₆ is acceptor-like according to the missing Poole-Frenkel effect. Therefore, it can be excluded that the EH₆-center and the prominent acceptor-like Z_1/2-center belong to different charge states of the same microscopic defect as theoretically suggested. It is proposed that EH₆ is a complex containing a carbon vacancy and another component available at high concentrations. The activation energy of EH₇ (E_C - E_T(EH₇) = 1.58 eV) has been evaluated indirectly by fitting the DLTS spectra of the EH_6/7 double peak taking the previously determined parameters of EH₆ into account.

Abstract: The results of experimental investigations of the dislocation-related DLTS-peaks originated from the dislocation networks (DN) are presented. Samples with DNs were produced by direct bonding of p-type silicon wafers and no enhancement of oxygen concentration was detected near the DN plane. Origins of the DLTS peaks were proposed and a correlation with the dislocation-related photoluminescence data was established based on known dislocation structure of the samples. Two types of shallow DLTS peaks exhibited Pool-Frenkel effect, which could be linked to the dislocation deformation potential. One of the shallow DLTS peaks was related to straight parts of screw dislocations and another - to the intersections of the dislocations.