The electrical characteristics of silicon carbide alloyed with germanium

• Published in: Applied surface science 2001-05, Vol.175-176, p.505-511
• Main Authors: Katulka, G, Roe, K, Kolodzey, J, Eldridge, G, Clarke, R.C, Swann, C.P, Wilson, R.G
• Format: Article
• Language: English
• Subjects: Alloys; Implantation; I–V characteristics; SiC; SiC:Ge
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/S0169-4332(01)00111-8

As an electronic material for high power, high voltage applications, silicon 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 Ge was implanted at 346keV and a dose of 1.67×1016cm−2 into a p-type 4H SiC wafer at room temperature, and followed by subsequent annealing up to 1700°C. Through X-ray diffraction (XRD) measurements it was determined that the Ge implanted SiC had a larger lattice constant which implies that some of the Ge is substitutional. The X-ray measurements indicated that a secondary peak attributable to substitutional Ge increases in intensity and shifted toward a lower Bragg angle as the implanted Ge dose was increased. SiC/SiC:Ge heterojunction devices were formed using titanium/gold (Ti/Au) as electrical contacts. Current–voltage (I–V) and capacitance measurements confirmed a reduction of the 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 used chromium/nickel (Cr/Ni) metalization as electrical contacts were shown to have a significantly lower contact resistance compared to SiC. These results indicate that the SiC/SiC:Ge material system may be promising for SiC heterojunction device applications.