I’m currently using Sentaurus TCAD to simulate space-charge-limited current (SCLC) in a 2D N⁺–i–N⁺ silicon diode structure with Ohmic contacts. My goal is to replicate the theoretical transition from Ohmic (J ∝ V) to Mott-Gurney (J ∝ V²) behavior in the I–V characteristics under trap-free conditions.
However, despite biasing the device up to 10,000 V, I’m only observing a linear (Ohmic) region in the I–V curve, and I haven’t been able to clearly see the onset of the MG regime.
Has anyone encountered similar issues or have suggestions on what simulation parameters (e.g., mobility model, doping levels, length-to-width ratio, voltage sweep settings, mesh refinement) might affect the ability to capture this transition?
Any guidance would be greatly appreciated!
interesting topic - please make sure that you make your analysis in an properly chosen intermediate voltage regime where the conditions for obtaining the Mott-Gurney (J ∝ V²) law are true.
Please refer to
https://en.wikipedia.org/wiki/Space_charge
and try the conditions mentioned there or similar ones
"As an application example, the steady-state space-charge-limited current across a piece of intrinsic silicon with a charge-carrier mobility of 1500 cm2/V-s, a relative dielectric constant of 11.9, an area of 10−8 cm2 and a thickness of 10−4 cm can be calculated by an online calculator to be 126.4 μA at 3 V. Note that in order for this calculation to be accurate, one must assume all the points listed above."
For both too small and too large voltages you will obtain linear regimes
(J ∝ V)
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