The electrical characteristics of silicon carbide alloyed with germanium

As an electronic material for high power, high voltage applications, silico n carbide (SiC) would be more versatile if suitable heterojunction partners were available. Using ion implantation, we have formed alloys of SiC with a few atomic percent of germanium (Ge). The Ce was implanted at 346 keV and a dose of 1.67 x 10(16) cm(-2) into a p-type 4H SiC wafer at room temperat ure, and followed by subsequent annealing up to 1700 degreesC. Through X-ra y diffraction (XRD) measurements it was determined that the Ce implanted Si C had a larger lattice constant which implies that some of the Ge is substi tutional. The Xray measurements indicated that a secondary peak attributabl e to substitutional Ge increases in intensity and shifted toward a lower Br agg angle as the implanted Ge dose was increased. SiC/SiC:Ge heterojunction devices were formed using titanium/gold (Ti/Au) as electrical contacts. Cu rrent-voltage (I-V) and capacitance measurements confirmed a reduction of t he forward voltage drop and built-in voltage in SiC:Ge, compared to similar SIC devices without Ge. Other p-type substrates implanted with Ge that use d chromium/nickel (Cr/Ni) metalization as electrical contacts were shown to have a significantly lower contact resistance compared to SiC. These resul ts indicate that the SiC/SiC:Ge material system may be promising for SiC he terojunction device applications, (C) 2001 Elsevier Science B.V. All rights reserved.