Advances in SiC materials and devices: an industrial point of view

Silicon Carbide (SiC) is an emerging semiconductor that has proven itself e specially well-suited to high temperature power switching and high-frequenc y power generation. In this paper we examine recent advances in materials d evelopment and device performance. In boule growth we have focused on incre asing boule diameter and reducing defect counts. Two conductivity types hav e been developed (1) semi-insulating for MESFETs, and (2) highly conducting boules for SITs and power switches. Very uniform planetary multi-wafer epi taxial layer growth on these wafers is described, in which specular epitaxi al layers have been obtained with growth rates of 3-5 mu m h(-1) exhibiting unintentional n-type doping of similar to 1 x 10(15) cm(-3), and room temp erature Hall mobilities of similar to 1000 cm(2) V-1 s(-1). Controlled n-ty pe doping between similar to 5 x 10(15) cm(-3) and >1 x 10(19) cm(-3) has a lso been demonstrated using nitrogen doping. SIC finds application in high temperature power switching devices and microwave power transistors. MOS Tu rn-Off Thyristors (MTO(TM)) are being investigated as power switches becaus e they offer ease of turn-off, 500 degrees C operation and reduced cooling requirements. In the fabrication of high-power, high-frequency transistors at UHF, L-, S-, and X-bands SIC has been found superior to both silicon and GaAs. For example, a 4H-SiC UHF television module has demonstrated good si gnal fidelity at the 2000 W PEP level, S-band transistor packages have show n 300 W peak power for radar applications, and 6 W power output has been ob tained at X-Band. (C) 1999 Elsevier Science S.A. All rights reserved.