S. Tohyama et al., A SILICON HOMOJUNCTION INFRARED DETECTOR HAVING AN ACTIVE METAL-FILM ON AN N++ LAYER, I.E.E.E. transactions on electron devices, 41(9), 1994, pp. 1535-1540
A silicon n++pn homojunction infrared detector, in which a degenerate
n++ layer is backed by a metal film forming an ohmic contact, has been
proposed and studied. The metal film is a photoelectric conversion re
gion along with the n++ layer. Although, for an n++pn detector without
the metal film, very poor rectifying properties are observed when the
n++ layer thickness is extremely reduced, the new detector, employing
a thin PtSi film as the metal film, shows normal diode I-V characteri
stics, since the PtSi film provides increased surface conductivity. Th
e new detector has achieved an increase in operatable temperature, or
an extension of cutoff wavelength, and operated with cutoff wavelength
s of 11.9 mum, 18.7 mum and about 30 mum at 70 K, 50 K, and 30 K, resp
ectively, because the saturation current density for the new detector
has been reduced to about one tenth that for the previously reported n
++pn detector. The responsivity for the new detector has increased to
1.1-3.8 times as large as that for the previously reported n++pn detec
tor, when both detectors have the same cutoff wavelength.