Lateral photodetectors with Ge quantum dots in Si

Lateral photodetectors with semiconductor quantum dots are novel devices using intrinsic properties of quantum dots such as the three dimensional confinement potential for carriers. On the InAs/GaAs material system they have proven their potential for highly efficient normal incidence operation. In this paper we present a detailed study of lateral photodetectors using intra-valence band transitions in self-assembled Ge dots. Two devices working at 3.3 and 4.4 mum wavelength are presented and compared to a vertical photodetector in the "classical" p(+)-i-p(+)design. The lateral devices show responsivities up to 10 mA/W even for small applied bias and detectivities up to 1 x 10(11) cm root Hz/W at T = 20 K. The lateral geometry is furthermore very promising for realizing large area devices with good detector characteristics. (C) 2001 Published by Elsevier Science B.V.