FABRICATION OF LATERAL NPN-STRUCTURES AND PNP-STRUCTURES ON SI SIGE BY FOCUSED LASER-BEAM WRITING AND THEIR APPLICATION AS PHOTODETECTORS/

Local doping with focused laser beam writing was used to fabricate lat eral npn- and pnp-structures on modulation-doped Si/SiGe heterostructu res. The electrical and optical properties of the achieved lateral pot ential modulation were analyzed for local B-doping on n-type Si/SiGe a nd P- and Sb-doping on p-type SiGe/Si. Focused laser beam written dope d lines show a strongly nonohmic IV characteristic indicating the form ation of a local insulating barrier in the two-dimensional carrier sys tem. Such lateral structures can be used as photosensitive devices wit h responsivities up to 10(6) A/W combined with a spatial resolution on the mu m scale. (C) 1997 American Institute of Physics.