Iron-related deep levels in n-type silicon

Abstract

Deep levels in iron-doped n-type silicon have been investigated by deep-level transient spectroscopy (DLTS). Three deep levels of Ec−0.29 eV (E1), Ec−0.36 eV (E2), and Ec−0.48 eV (E3) were observed. The concentration of E1 and E2 levels increased during the storage at room temperature. The depth profile of the E3 level concentration indicates the out-diffusion and precipitation of the defects related to the E3 level. In addition, after annealing at 80 °C for 30 min, the E2 and E3 concentrations decreased and then recovered at room temperature. These results suggest that the defects related to these levels are mobile during quenching and storage at room temperature. The temperature dependence of the E3 level concentration shows a formation energy of about 2 eV, which is smaller than that of interstitial iron, and the E3 level concentration is two orders of magnitude lower than the concentration of interstitial iron. The origins of these levels are probably loosely associated iron-related complexes such as iron-acceptor pairs.

Fe‐Related Defects in Si: Laplace Deep‐Level Transient Spectroscopy Studies

“…Several Fe-related defects were also previously reported after the iron diffusion at around 1000-1200 °C in n-type Si in the literature and they were attributed to interstitial Fe clusters, [18] Fe i complexes, [19] or Fe-related defects. [20] However, the electrical properties of the defects differ significantly from those of E125 FeH , E145 Fe , and E240 Fe observed in the present study and therefore they belong to different defects. We did not observe E125 FeH , E145 Fe , and E240 Fe in samples without Fe and, therefore, we attribute these levels to Fe-related defects.…”

In-Diffusion and Isothermal Annealing of Iron-Related Defects in Czochralski N-Type Silicon

“…1,2) However, some understandings of the introduction of iron-related defects in floating zoned (FZ) n-type silicon have been obtained from a series of indiffusion and annealing study of iron-doped silicon. [3][4][5][6] The in-diffusion and annealing characteristics indicate that the observed iron-related defects are due to complexes in FZ n-type silicon.…”

Electrical property of iron-related defects in n-type dislocated Czochralski silicon crystal used for solar cells

“…4) In n-type silicon, 3 or 4 new lines can be detected in deep level transient spectroscopy (DLTS) spectra after iron diffusion. [5][6][7][8][9][10] From isothermal annealing properties, these defects can be related to iron-related complexes or a consecutive progress of iron precipitation reaction and are independent of phosphorus and oxygen atoms. 8,10) In addition, multi-crystalline silicon (mc-Si) is now widely used for photovoltaics for its low cost compared with Czochralskigrown silicon (Cz-Si).…”

“…Table I shows the results of the previous studies and our study, regarding parameters of iron-related defects in n-Si for comparison. [5][6][7][8][9][10] Nakashima and Chijiwa 5) reported two levels at E c -0.36 and E c -0.56 eV, which are attributed to a cluster of interstitial iron atoms. Kakishita et al 6) found three levels at E c -0.29, E c -0.36 and E c -0.48 eV after storage of iron-doped n-type silicon for 30 days at room temperature, which are attributed to iron-related complexes.…”

“…[5][6][7][8][9][10] Nakashima and Chijiwa 5) reported two levels at E c -0.36 and E c -0.56 eV, which are attributed to a cluster of interstitial iron atoms. Kakishita et al 6) found three levels at E c -0.29, E c -0.36 and E c -0.48 eV after storage of iron-doped n-type silicon for 30 days at room temperature, which are attributed to iron-related complexes. Tanaka et al 8,10) have also observed the same DLTS spectra in n-type Cz and Fz silicon containing different oxygen and phosphorus content, and suggested that the observed defect levels were not related to phosphorus and oxygen atoms.…”