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

Silicon Carbide (SiC) is an emerging semiconductor that has proven itself especially well-suited to high temperature power switching and high-frequency power generation. In this paper we examine recent advances in materials development and device performance. In boule growth we have focused on increasing boule diameter and reducing defect counts. Two conductivity types have been developed (1) semi-insulating for MESFETs, and (2) highly conducting boules for SITs and power switches. Very uniform planetary multi-wafer epitaxial layer growth on these wafers is described, in which specular epitaxial 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 temperature Hall mobilities of similar to 1000 cm(2) V-1 s(-1). Controlled n-type doping between similar to 5 x 10(15) cm(-3) and >1 x 10(19) cm(-3) has also been demonstrated using nitrogen doping. SIC finds application in high temperature power switching devices and microwave power transistors. MOS Turn-Off Thyristors (MTO(TM)) are being investigated as power switches because 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 signal fidelity at the 2000 W PEP level, S-band transistor packages have shown 300 W peak power for radar applications, and 6 W power output has been obtained at X-Band. (C) 1999 Elsevier Science S.A. All rights reserved.