Deep-level transient spectroscopy and Hall effect studies of NTD silicon with different initial resistivities

Abstract

Radiation damage was studied by deep-level transient spectroscopy and Hall effect measurements for the neutron-transmutation-doped silicon of initially high-and low-resistivity (phosphorus-contained) materials. In the irradiated materials a total of twelve electron traps was observed. A large reduction of carrier concentration and a small reduction of carrier mobility were found in the initially low-resistivity samples ( c 1 2 R cm), correlated closely with the divacancy responsible for two traps ( E 4 and E8). For the initially highresistivity samples ( > 1000 R cm) results showed large reductions of carrier concentration and mobility; these reductions are closely correlated with electron traps E3, E5 and E10. It appeared that the latter three traps correspond to some energy levels within the fast-neutron-induced defect clusters. However, in the initially low-resistivity samples, t h e formation of these traps appeared to be controlled by initially doped phosphorus atoms. In other words, due to the difference in the annealing temperature of divacancy and defect cluster, the annealing-out temperatures of carrier concentration and mobility were lower for the initially low-resistivity samples in comparison with t h e initially highresistivity samples.

Annealing behaviour of excess carriers in neutron-transmutation-doped silicon

“…The decrease of defect concentration in the sample RI to below 10" cm-3 by annealing up to 680 "C for 60 min has been confirmed hy the DLTS measurements of electron and hole trap defects [4,5]. In agreement, the results of figure 1 showing the ratio n/no -1.0 for annealing at 740 "C for samples HS and W imply that the concentration of radiation damage has little effect on the free electrons.…”

“…the DLTS spectra of cz NTD Si differ fundamentally from those of FZ NTD Si, as shown in figure 8. Thus, it appears that the formation of nuclei has not occurrcd in the MD process but rather in the annealing process as the high oxygen content in cz crystal prevents the formation of nuclei during the annealing process with the tendency to form divacancies in such a crystal [4,23].…”

“…The virtual restoration of carrier mobiiity is observed by annealing at 650 T for 60 min [3]. From deep-level transient spectroscopy (DLTS) measurements, it is known that the electrically active radiation damage decreases in concentration (< 10" below the limit of detection after annealing at about 750 "C for 60 min [4,5].…”

Temperature Dependent Investigation on Optically Active Processes of Higher-Order Bands in Irradiated Silicon

“…The similar annealing behavior of the residual absorption for the samples annealed for 40 and 100 h implies that their defect states are almost the same. Indeed, the evolution of defects in irradiated silicon is predominantly controlled by the annealing temperature [13]. As observed above, the relaxation behavior of photoexcited carriers is a non-monotonous function of temperature.…”