Ir. Tamm et al., PHOTOSIGNAL ENHANCEMENT IN AL-GAAS DIODES DUE TO SURFACE-PLASMONS ANDGUIDED-WAVE MODES, Journal of applied physics, 74(12), 1993, pp. 7481-7487
Light of wavelength 632.8 nm and p-polarization is incident on a prism
-air gap (varied from 0.7 to 7 mum)-Al-GaAs arrangement. Both the phot
osignal generated by the Schottky diode and the reflectance are measur
ed as a function of the internal angle of incidence in the prism. Ther
e is significant, well-defined enhancement of the photosignal, up to a
factor of approximately 7.5, associated with two different types of e
nhanced absorption modes. For air gaps < 1.5 mum there is photosignal
enhancement due to an enhanced absorption feature (reflectance dip) th
at occurs at an angle of incidence just above critical angle in the pr
ism; this feature corresponds to the excitation of a surface plasmon p
olariton at the Al-air interface. For air gaps > 1 mum there are betwe
en one and ten photoresponse peaks at input angles less than the criti
cal angle. The corresponding enhanced absorption features are due to l
eaky guided wave modes set up in the air gap.