Correlation between variable-range hopping conduction and lattice strain in heavily Al-doped 4H-SiC epilayers

Abstract The correlation between variable-range hopping conduction and key material parameters is investigated, including the Al concentration ( C Al ), the full width at half maximum (FWHM) of the X-ray diffraction peak, and the lattice strain in heavily Al-doped 4H-SiC epilayers with C Al exceeding 10 20 cm −3 . The characteristic temperature T 0 derived from the gradient of Mott plots (i.e. <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>ln</mml:mi> <mml:mi>ρ</mml:mi> <mml:mo stretchy="false">(</mml:mo> <mml:mi>T</mml:mi> <mml:mo stretchy="false">)</mml:mo> </mml:math> versus T −1/4 ) of the temperature-dependent resistivity ρ ( T ) decreases with increasing C Al . Meanwhile, the FWHM correlates positively with C Al . Because the density of localized states at the Fermi level, g ( E F ( T )), is inversely proportional to T 0 , g ( E F ( T )) increases as a power function of C Al . It also increases with the lattice strain.