Page 4 - Carrier Recombination Activity and Structural Properties of Small-Angle Grain Boundaries in Multicrystalline Silicon

Jpn. J. Appl. Phys., Vol. 46, No. 10A (2007) J. CHEN and T. SEKIGUCHI

Clean mc-Si_#1 Clean mc-Si_#2 Clean mc-Si_#3 Clean mc-Si_#4
(a) (e) (a) (e)

SE SE

(b) (f) (b) (f)
Σ9 Σ11 2-2.5°
R R Σ3 5° R Σ9 R
EBSD 2.5° 4.5° 9.5° Σ3 Σ3 EBSD 2° 2.5-3°

3° Σ3 1.5° 1°
R Σ3 9.5° R 1° R
9.5°
1°
1°
(c) (g) (c) (g)

EBIC_300 K EBIC_300 K

(d) (h) (d) (h)

EBIC_100 K EBIC_100 K

200 µm 200 µm

Fig. 2. SE, EBSD, and EBIC images of SA-GBs with weak EBIC contrast Fig. 3. SE, EBSD, and EBIC images of SA-GBs with strong EBIC
at 300 K in clean mc-Si (samples #1 and #2). contrast at 300 K in clean mc-Si (samples #3 and #4).

3.1 SA-GBs in clean mc-Si EBIC contrast (0–5%), while in the EBIC images taken at
3.1.1 Recombination activity of clean SA-GBs 100 K, all the SA-GBs appeared as dark lines with an EBIC
Figure 2 shows secondary-electron (SE), EBSD, and contrast of 20–50%.
EBIC images of two clean mc-Si samples (#1 and #2). Figure 3 shows SE, EBSD and EBIC images of other
The EBSD images are represented by line drawings, in clean mc-Si samples (#3 and #4), in which some SA-GBs
which the SA-GBs are denoted in terms of their tilt angles. showed strong EBIC contrast even at 300 K. In the EBIC

SA-GBs with tilt angle 1 were categorized into the SA1 images taken at 300 K, as denoted by arrows, the SA2 in

group, and so on. LA-GBs ( and R) were also found in the sample #3, and the SA2–2.5 and SA2.5–3 in sample #4
EBSD images. In the SE images, SA-GBs with smaller tilt showed particularly strong contrast of up to 30%. The

angles (0–3 ) could not be easily observed, while the SA- contrast of SA-GBs with tilt angle less than 1.5 was still

GBs with larger tilt angles (4.5–9.5 ) and LA-GBs were weak. LA-GBs such as 9 and R showed weak contrast. In
frequently observed. Such a difference originates from the the EBIC images taken at 100 K, all the SA-GBs appeared as
chemical etching during the polishing of mc-Si samples. dark lines with strong EBIC contrast, which was similar to
GBs with a large misorientation angle were easily revealed the SA-GBs in samples #1 and #2 shown in Fig. 2.
due to the heterogeneous etching of grains with different The distributions of the EBIC contrast of SA-GBs at 300

orientations, while GBs with a small misorientation angle and 100 K with respect to tilt angle (0.5 step) are shown in

were not easily revealed due to the homogeneous etching. Fig. 4. SA-GBs with a larger tilt angle (5–10 ) showed weak
EBIC images were taken at 300 and 100 K. In the EBIC EBIC contrast and were simply classified into the group of

images taken at 300 K, Both SA- and LA-GBs showed weak SA5 . According to the distribution of 300 K EBIC contrast,
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