Effect Of Germanium Doping On The Irradiation Hardness Of Czochralski Silicon Material And Device

Devices based on Czochralski (CZ) silicon are widely used in all kinds of radiation environments. Improvement of the irradiation hardness of CZ silicon continuously is a last long task. It is generally believed that germanium (Ge) doping technology can enhance the irradiation hardness of CZ silicon material. But the effect on neutron-irradiation-defects has yet to unfold. In this dissertation, the characterizations of current-voltage (I-V) and capacitance-voltage (C-V) were to investigate the irradiation hardness of PN diode based on highly Ge doped Czochralski (GCZ) silicon, and the fourier transform infrared spectrometer (FTIR) was to research the effect of Ge doping on fast neutron induced defects in CZ silicon wafers.The impact of germanium (Ge)-doping at a level of1020cm-3in Czochralski silicon on the neutron-irradiation-induced degradation of electrical performance of PN junction diodes has been investigated. The characterizations of current-voltage (â… -â…¤) and capacitance-voltage (C-V) were employed to investigate the degradation of electrical performance of the diodes irradiated by fast neutron. It was found that after neutron irradiation the Ge-doped diode had much lower increasing rates of forward and reverse currents with respect to the conventional diode. This indicates that the Ge-doping to a certain extent reduces the neutron-irradiation-induced deep-level defects, thus improving the radiation hardness of Si diode.The thermal behavior of neutron-induced defects was characterized by the evolution of interstitial oxygen concentration [0;]. Under low temperature anneal, the decreasing rate of [Oi] was lower in GCZ silocon wafer, which is assumed that the transformation process of VO to complicated vacancy-oxygen complexes (VmOn) is retarded by Ge-doping. The assumption is comfirmed by studying the oxygen preciitation after neutron irradiation as VmOn can be heterogeneous nucleation centers for oxygen precipitates thus improving oxygen precipitation. Less OiS involve precipitation in GCZ silicon than that in CZ silicon, implying the suppressed conversion process of neutron-induced-defects to nucleation centers.