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Название: Metrology-driven differentiation of isotypic and anisotypic SiC/Si heterojunctions for
betavoltaic energy conversion
Ключевые слова: S 3C-SiC/Si heterojunction, betavoltaic cell, isotypic vs anisotypic, interface states, Kelvin probe force microscopy (KPFM), scanning tunneling spectroscopy (STS), charge accumulation, Keithley 2450, metrology, TCAD modelling
Аннотация: We present a comprehensive metrological comparison of isotypic (n-SiC/n-Si) and anisotypic (n-SiC/p-Si) heterojunctions grown by high-temperature chemical vapour deposition (endotaxy). Using a combination of Kelvin probe force microscopy (KPFM), scanning tunnelling spectroscopy (STS), and precision
electrical measurements (Keithley 2450 SourceMeter), we demonstrate that the commonly reported “superior”
current–voltage characteristics of isotypic structures under two-probe probing are an artefact caused by a high density of interface states (Dit > 5 × 1012 cm−2eV−1) that promote trap-assisted tunnelling (TAT) and create spatially inhomogeneous Schottky barrier patches. In contrast, anisotypic junctions exhibit a genuine p–n behaviour whose intrinsic performance can only be revealed when four-wire Kelvin sensing, correct polarity (cathode to LO), and a high-impedance output-off state are employed. An integral charge-storage test on a supercapacitor (C = 0.1 F) reveals a more than fivefold faster charging rate and a ∼ 25-fold higher stored energy for anisotypic structures, in quantitative agreement with the band-diagram predictions and previously reported betavoltaic Si14C–Si converter performance. Based on our in situ KPFM/STS mapping (spatial resolution 30 nm, threshold activation delay ta = 2.3±0.5 s, stretched-exponential relaxation τ = 35±2 s, β = 0.65±0.05), we formulate unambiguous guidelines for TCAD modelling and experimental characterisation, thereby eliminating
the long-standing discrepancy between material engineers and metrology experts. Raw KPFM/STS maps, I–V parameter-extraction data, and the patented charge-pump/supercapacitor converter architecture underlying the present comparison have been reported in detail in our companion methodological, structural and device publications, which are cited throughout.
Язык рукописи: English
Авторы:Mikhail V. Dolgopolov,
Samara State Technical University, Samara, Russian Federation
