Chemistry Reference
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interface has a very low surface recombination velocity and gives a photo response
similar to that at a silicon/metal interface. The long wavelength spectral response is
dominated by the collection properties of the photo generated minority carriers. The
response at short wavelength (200-600 nm), at which the penetration depth is smaller,
is affected by both the collection properties of the majority and minority carriers. Also,
at short wavelength the photo generated carriers are influenced by both the field and
concentration gradient. This leads to a wavelength dependent majority carrier pho-
tocurrent, which opposes the minority carrier photocurrent, resulting in a lowered
quantum yield at short wavelengths as shown in Fig. 5.15.
Photocurrent on
n
-Si can also be caused by surface generation processes with
sub-band-gap light illumination.
400
Figure 5.16 shows that the quantum yield from sub-
