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(a) Schematic cross-sectional view of sample showing the 3C inclusions ( lines) which start to fill with free carriers (electrons) at the depth below the interface, while the surrounding 4H area remains depleted even in the bulk. (b) BEEM image (taken with tip voltage) of a sample with embedded 3C inclusions. The bright straight lines show reduced SBH where the 3C QW inclusions intersect the interface. (More details are given in Ref. 8.)
Top two lines: Calculated curves without QWs, with (dashed line) and (solid line), and parameter values from Table I. Changing has little effect on the intercept voltage. Bottom two lines: Calculated curves with inclined QWs present, with , , parameters from Table I, and with (dotted-dashed line) and (dotted line). Introducing QWs strongly reduced the intercept voltage, but not the shape or slope of the calculated curves. Changing still has little effect on the intercept voltage. (엯) Measured data from a diode on the wafer periphery without inclusions. (◻) Measured data from Diode A from the central part of the SiC wafer with inclusions.
Calculated electron potential energy profiles for Diode B along the particular path perpendicular to the interface shown as a dotted line in Fig. 1(a). The solid line represents the three-dimensional conduction-band minimum for bulk 4H- and 3C–SiC, while the horizontal dotted lines represent the two-dimensional conduction-band minimum of the QW states, including quantum confinement energy. The overall band bending is decreased with respect to pure 4H–SiC (dashed line) by charging of the QWs deep in the bulk, with a corresponding reduction in measured SBH. Inset: Close-up view of QW profile around an inclusion.
The parameter values from the literature (citation in parentheses) used in finite-element electrostatic modeling.
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