Modeling of Lattice Site-Dependent Incomplete Ionization in α-SiC Devices

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[5] C. M. Zetterling, EMIS series, no. 2, INSPEC, IEE, UK (2002).100 200 300 400 500 600 700 800 Temperature [K] 0 0.2 0.4 0.6 0.8 1 Ionization degree (ξD) ∆ED(k/h) = 50/90 meV ∆ED = 70 meV ND=10 15cm-3 ND=10 19cm-3 ND=10 17cm-3 Fig. 1: Comparison of ionization degree of donors (N) assuming an effective and a sitedependent activation energy in 4H-SiC. 1015 1016 1017 1018 1019 10 20 1021 ND [cm -3 ] 0 0.2 0.4 0.6 0.8 1 Ionization degree (ξD) 700 K 500 K 300 K ∆ED(h/k) = 50/90 meV Fig. 2: Ionization degree of donors (N) assuming a site-dependent activation energy in 4H-SiC. 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 x [um] −5 −4 −3 −2 −1 −0 y [um] < −0 50 100 200 300 400 500 600 700 800 >900 Source Gate p well n+ n− Fig. 3: The carrier mobility at 300K in 4HSiC UMOSFET utilizing the lattice site dependent ionization level model. 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 x [um] −5 −4 −3 −2 −1 −0 y [um] Source Gate n+ p well n− >350 300 250 200 150 100 50 25 < −0 Fig. 4: The carrier mobility at 500K in 4HSiC UMOSFET utilizing the lattice site dependent ionization level model. 0 5 10 15 Gate voltage [V] 0.05 0.1 0.15 0.2 0.25 0.3 Drain current [A/cm] ∆ED(k/h) = 50/90 meV ∆ED = 70 meV 300 K 500 K 700 K VDS= 5 V Fig. 5: Comparison of transfer characteristics of a 4H-SiC UMOSFET using an effective and a site-dependent activation energy. 1015 1016 1017 1018 1019 1020 1021 ND [cm -3 ] 10 0 10 1 10 2 10 3 10 4 10 5 Resistivity [Ω-cm] ∆EDk/h = 50/90 meV ∆ED = 70 meV 300 K 500 K 700 K Fig. 6: Resistivity of n-type 4HSiC calculated from the doping- and temperature dependent mobility.

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