Dependence of spontaneous polarization on stacking sequence in SiC revealed by local Schottky barrier height variations over a partially formed 8H-SiC layer on a 4H-SiC substrate

Abstract

Ballistic electron emission microscopy was used to measure the increase of local Schottky barrier (compared to the surrounding 4H-SiC area) over a partial 8H-SiC layer that is the surface-exposed tail of an 8H stacking fault inclusion extending from 4H substrate. This local increase is believed to be due to polarization charge induced at the interface of partial 8H layer and underlying 4H host, resulting from the spontaneous polarization (SP) difference between SiC regions with different bilayer stacking. This is a direct experimental probe of the dependence of SP in SiC on local stacking sequence by measuring carrier transport.

Photoluminescence of 8H-SiC

“…Degradation problems of bipolar devices have led to many studies of 8H-like stacking faults in 4H-SiC including high resolution transmission microscopy and photoluminescence (PL) [1,2]. In these studies the 8H polytype material appears as very small inclusions of few nm size.…”

Schottky barrier modulation of metal/4H-SiC junction with thin interface spacer driven by surface polarization charge on 4H-SiC substrate

“…In case of n-type Si-face 4H-SiC substrate, the interface SB is expected to increase due to the negative polarization charges induced on the 4H-SiC surface. 11,12 As model systems to evaluate this idea, Au/Ni/4H-SiC and Au/Ni/Al 2 O 3 /4H-SiC junctions are compared in terms of their electrical properties including current-voltage (I-V) and capacitance-voltage (C-V) characteristics.…”