CAN CARBON-IMPLANTED SILICON BE APPLIED AS WIDE-BANDGAP EMITTER

We examine the formation of Si1-xCx (x = 0.04-0.2) by means of CFy (y = 0, 1, 3) implantation in p-type Si, for application as a wide-bandga p emitter in a Si heterojunction bipolar transistor. Upon implantation with 2.5 x 10(16) CF+/cm(2) at 45 keV, and subsequently with 2.5 x 10 (16) C+/cm(2) at 30 keV, an amorphous top layer is formed. Annealing a t temperatures up to 900 degrees C leads to a layer consisting of nano crystalline material. High resolution transmission electron microscopy and secondary ion mass spectrometry show that a well-defined nanocrys talline/crystalline interface is created at an anneal temperature of 5 50 degrees C. At higher temperatures lattice defects start to develop. Preliminary attempts to dope the material via phosphorus or arsenic i mplantation indicate that temperatures of at least 900 degrees C are r equired to activate a fraction of the implanted dopants. This, however , adversely affects the adlayer/substrate interface.