Deep level transient spectroscopy and minority carrier lifetime study on Ga-doped continuous Czochralski silicon

Abstract

Continuous-Czochralski (c-Cz) crystal growth has been suggested as a viable technique for the fabrication of photovoltaic Si wafers due to its low resistivity variation of any dopant, independent of segregation, compared to conventional Cz. In order to eliminate light induced degradation due to boron-oxygen traps in conventional p-type silicon wafers, gallium doped wafers have been grown by c-Cz method and investigated using four point probe, deep level transient spectroscopy (DLTS), and microwave-photoconductance decay. Iron-gallium related electrically active defects were identified using DLTS as the main lifetime killers responsible for reduced non-uniform lifetimes in radial and axial positions of the c-Cz silicon ingot. A direct correlation between minority carrier lifetime and the concentration of electrically active Fe-Ga pairs was established.

Imaging Interstitial Iron Concentrations in Gallium‐Doped Silicon Wafers

“…As mentioned in Section 3.1, this factor is determined by the sample doping, the injection level and the SRH recombination parameters of the defects. There is a variety of parameters for iron defects determined from deep level transient spectroscopy (DLTS) and lifetime measurements . Choosing the right parameter set for the iron evaluation is crucial.…”

“…There is a variety of parameters for iron defects determined from deep level transient spectroscopy (DLTS) and lifetime measurements. [6][7][8][9][10][11]17] Choosing the right parameter set for the iron evaluation is crucial. We have demonstrated in the past that in B-doped silicon the SRH parameters determined by Istratov et al for the Fe i -state are in good agreement with the DLTS measurements.…”

“…Since iron contamination is such a common problem a thorough investigation of the effects of iron in combination with boron and gallium needs to be conducted in order to be able to assess the impact of iron on the electrical quality of silicon. Macdonald et al examined the difference in the formation rates of iron‐acceptors for different dopants, Schmidt et al and Naerland et al suggested Shockly–Read–Hall (SRH) parameters for the FeGa defect state centers, and several DLTS evaluations of the FeGa defect exist already …”

“…Macdonald et al examined the difference in the formation rates of iron-acceptors for different dopants, [5] Schmidt et al and Naerland et al suggested Shockly-Read-Hall (SRH) parameters for the FeGa defect state centers, [6,7] and several DLTS evaluations of the FeGa defect exist already. [8][9][10][11] The effects and influences of iron on B-doped samples are well known and with the method by Zoth and Bergholz [12] it is possible to determine the Fe-concentration within a sample. Using laterally resolved lifetime measurements it is even possible to determine the Fe-concentration in a spatially resolved manner, as described by Macdonald et al [13] A lateral evaluation of iron contamination is particularly handy for the analysis of laterally inhomogeneous samples and effects within these, like the influence of gettering or the identification of contamination sources.…”

Lead Selenide Polycrystalline Coatings Sensitized Using Diffusion and Ion Beam Methods for Uncooled Mid-Infrared Photodetection

“…can form non-equilibrium carrier traps or recombination centers. The characterizations on the concentration distribution, compositional identification, and the capture cross-section of the trap centers are important to understand the carrier transport and recombination mechanisms [47,106,107]. However, these characterizations seem to be difficult to perform, because they need more complex analysis to extract the physical mechanisms from limited experimental characterizations.…”