IMPURITY DISTRIBUTION AND ELECTRICAL CHARACTERISTICS OF BORON-DOPED SI1-XGEX/SI P(+)/N HETEROJUNCTION DIODES PRODUCED USING PULSED UV-LASER-INDUCED EPITAXY AND GAS-IMMERSION LASER DOPING

A two-step pulsed UV-laser process which independently controls the metallurgical and electrical junction depth of a Si1-xGex/Si heterojunction diode has been implemented. Pulsed Laser-Induced Epitaxy (PLIE) combined with Gas-immersion Laser Doping (GILD) are used to fabricate boron-doped heteroepitaxial p+/N Si1-xGex/Si layers and diodes. Borontrifluoride is used as the gaseous dopant source in the GILD process step. Boron incorporation and activation are investigated as a function of laser energy fluence and the number of laser pulses using SIMS and Hall-effect measurements. The dose of incorporated dopant is on the order of 10(13) cm-2 per pulse. The B profiles obtained are flat except for a peak at the interface resulting from segregation effects. The B and Ge distributions are compared with shifts in the turn-on voltage of p+/N Si1-xGex/Si heterojunction diodes produced by the process. The GILD/PLIE process is spatially selective with the resulting diodes fabricated being quasiplanar. Hole mobilities in the heavily doped Si1-xGex films are found to be slightly lower than in comparable Si films.