Spin-lattice relaxation in aluminum-doped semiconducting 4H and 6H polytypes of silicon carbide.
NMR spin-lattice relaxation efficiency is similar at all carbon and silicon sites in aluminum-doped 4H- and 6H-polytype silicon carbide samples, indicating that the valence band edge (the top of the valence band), where the holes are located in p-doped materials, has similar charge densities at all atomic sites. This is in marked contrast to nitrogen-doped samples of the same polytypes where huge site-specific differences in relaxation efficiency indicate that the conduction band edge (the bottom of the conduction band), where the mobile electrons are located in n-doped materials, has very different charge densities at the different sites. An attempt was made to observe (27)Al NMR signals directly, but they are too broad, due to paramagnetic line broadening, to provide useful information about aluminum doping.
Department of Chemistry, Brock University, St. Catharines, Ontario, Canada. shartman@brocku.ca
J Stephen
JS
Hartman
Bob
B
Berno
Paul
P
Hazendonk
Philip
P
Hens
Eric
E
Ye
Alex D
AD
Bain
D000535:Aluminum / Q000737:chemistry*; D017554:Carbon Compounds, Inorganic / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D012666:Semiconductors; D017655:Silicon Compounds / Q000737:chemistry*
D017554:Carbon Compounds, Inorganic; D017655:Silicon Compounds; D000535:Aluminum; C022088:silicon carbide