Dislocation proliferation at the growth crystal/seed interface of physical vapor transport-grown 4H-SiC crystals

Abstract 4H-SiC single crystal with [000 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover accent="true"> <mml:mn>1</mml:mn> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> ] direction 4° off axis was prepared by physical vapor transfer method. To enlarge the observed interface area between the seed crystal and the nascent crystal, the wafers were processed at an Angle of approximately 2° in the (000 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover accent="true"> <mml:mn>1</mml:mn> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> ) plane. The longitudinal optical phonon-plasmon coupled (LOPC) mode was measured by a laser Raman spectrometer, and the location of the growth interface was determined by evaluating the free carrier concentration at the seed-crystal interface. The defect structure at the seed-crystal/newly grown crystal interface and in nearby regions was examined by high-resolution x-ray diffractometry. The change in stress at the interface was characterized by a stress tester; the results showed that a greater stress at the interface correlated to more proliferated dislocations. The dislocation morphologies in the interfacial regions of different seed grains etched by molten KOH were observed via microscopy.