HYDROGEN INCORPORATION AND ITS TEMPERATURE STABILITY IN SIC CRYSTALS

SiC is an important wide bandgap semiconductor material with use in hi gh temperature electronics and as a substrate for III-V nitride epitax ial growth. In several processing stages that are required for such ap plications, atomic hydrogen may be introduced into the SiC material. S ince atomic hydrogen is able to passivate shallow donors or accepters, device performance may be affected. Here we report on the incorporati on of hydrogen and its thermal stability in 6H-SiC crystals. Hydrogen was introduced either through ion implantation or by plasma treatment. Implantation of H-2 was performed at an energy of 100 keV to a fluenc e of 2 x 10(15) cm(-2). In the as-implanted sample, a classical implan t profile with a H-2 density of about 10(20) cm(-3) at a depth of abou t 0.75 mu m was obtained using secondary ion mass spectrometry (SIMS). Other samples were exposed to a H-2 plasma for 30 min at 300 degrees C; While the SIMS profiles of the plasma treated samples had a H-2 pea k density at the surface of about 10(20) cm(-3), the background level of H-2 was reached in less than 0.1 mu m. Samples were furnace anneale d under flowing N at temperatures up to 1000 degrees C. In contrast wi th Si and III-V materials, there was no significant redistribution of H-2 in the implanted SiC crystal with annealing. For plasma treated sa mples, annealing led to a significant reduction of H-2. (C) 1997 Elsev ier Science Ltd.