H. Aharoni et al., ANALYSIS OF N(+)P SILICON JUNCTIONS WITH VARYING SUBSTRATE DOPING CONCENTRATIONS MADE UNDER ULTRACLEAN PROCESSING TECHNOLOGY, Journal of applied physics, 81(3), 1997, pp. 1270-1288
Using highly controlled ultraclean processing technology, marked impro
vements in n(+)p Si junction quality are achieved presenting a theoret
ical significance. Boron-doped substrates with various boron doping co
ncentrations N-s were As+ implanted, forming the n(+) junction sides.
The diffusion (Id) and generation (I-gen) currents, as well as the ide
ality and the generation factors, are significantly reduced, and bulk
generation lifetimes are prolonged. Using Shockley-Read-Hall theory it
is found that a deviation of the trapping centers energy (E(t)) from
the midband-gap energy (E,) is responsible for the improvements. The e
xperimental results show that \E(t)-E(i)\ is a function of N,, and tha
t the I-gen/I-d ratio is significantly low. Accordingly, it is propose
d that I-gen/I-d ratio should be regarded, under certain conditions, a
s a figure of merit for junction quality. It is concluded that the \E(
t)-E(i)\ deviation is related to the ultraclean processing technology
used, due to the formation of new energy levels far from Ei and the su
ppression of introduction of new energy levels near Ei. Surface genera
tion currents were found experimentally to be significant, and thus no
t negligible. Surface effects in general demonstrated similar trends t
o the bulk generation effects. (C) 1997 American Institute of Physics.