Investigations on residual strains and the cathodoluminescence and electron beam induced current signal of grain boundaries in silicon

Abstract

Cathodoluminescence (CL) and electron beam induced current (EBIC) measurements were used to investigate the optical behavior and electrical activity of grain boundaries (GBs) in coarsely grained silicon. Electron backscatter diffraction (EBSD) was applied for a comprehensive characterization of the structural properties of the high angle and low angle GBs (HAGBs and LAGBs) in the sample. It was found that not only the EBIC but also the panchromatic (pan) CL contrast of Σ3 HAGBs strongly depends on the hkl-type of the boundary plane. At room temperature coherent Σ3 GBs exhibit no significant contrast in the CL or EBIC images, whereas at low temperatures the pan-CL contrast is strong. For incoherent Σ3 GBs, a strong pan-CL and EBIC contrast was observed in the entire temperature range. Only on a LAGB (misorientation angle 4.5°) CL investigations at low temperatures revealed a line with peak position at about (0.82 ± 0.01) eV, usually related to the dislocation associated D1 transition. Cross-correlation EBSD was applied to analyze the strain fields of Σ3 HAGBs as well as of the LAGB. All the components of the local strain tensors were quantitatively determined. The relationship between the extension of the strain field at the LAGB and the spatial D1 intensity distribution is discussed.

Compositional and electrical properties of line and planar defects in Cu(In,Ga)Se2 thin films for solar cells – a review

“…For these results, which have been reproduced on different Cu(In,Ga)Se 2 solar cells with varying [In]/[Ga] concentrations in the absorber , nonradiative recombination, enhanced at extended structural defects in Cu(In,Ga)Se 2 , can be considered as one possible explanation. This scenario would be similar to that at grain boundaries and dislocations in multicrystalline Si , for which the model of nonradiative, Shockley–Read–Hall (SRH) recombination via deep trap states in the band gap (induced by impurities or more generally point defects) is established . These trap states are the result of excess charge densities at grain boundaries or dislocations, which lead to a corresponding electrostatic potential distribution (band bending).…”

X-ray-to-current signal conversion characteristics of trench-structured photodiodes for direct-conversion-type silicon X-ray sensor

“…The diameter of the photoelectrically generated primary charge cloud produced by absorbing an X-ray photon with the energy E keV can be approximated as R = 0.0171 × E 1.75 µm. [32][33][34][35][36] For 80 keV X-rays, which are typically used in medical diagnosis applications, the generated primary charge cloud diameter is 37 µm in the silicon substrate; therefore, the pixel is sufficiently larger in size than the primary charge cloud. Figure 7 shows a cross-sectional illustration of the trench- structured photodiodes.…”

Effect of Strain on Interactions of Σ3{111} Silicon Grain Boundary with Oxygen Impurities from First Principles

“…Moreover, the distribution of intrinsic strain and its relation to electrical activity on as‐grown mc‐Si have been probed experimentally in recent times as well. [ 12–14 ] Particularly, for metal precipitates correlation between carrier lifetime, stress and precipitate size has been observed. [ 15 ] Stress not only leads to fracture and breakage during handling and processing but, through the strain produced, may also influence electrical activity and hence affect the performance of furnished solar cells.…”

“…Furthermore, some Si-GBs present residual strain, as detected by infrared polariscope or Raman spectroscopy [9,10], and relation of strain with longer carrier lifetime [11] has been reported. Moreover, the distribution of intrinsic strain and its relation to electrical activity on as-grown mc-Si has been probed experimentally in recent times as well [12,13,14]. Particularly, for metal precipitates correlation between carrier lifetime, stress and precipitate size has been observed [15].…”