Geometric Nanodiode: Self-Switching Rectification

Drive

Bias voltage V 0.60 V

AC amplitude V₀ 0.90 V

Channel Geometry

Bend angle θ 130°

Neck width w 14 nm

Live Readout

Current I(V)0.00 pA

Rectification I(+1V)/I(−1V)1.0×

e⁻ transmitted/s0

How it works

A self-switching diode (SSD) is a real nanoelectronic rectifier (Song et al., 2003) etched from a single semiconductor sheet with two insulating trenches cut through it, leaving a narrow, bent conducting channel — no p-n junction and no doping gradient at all. It rectifies purely from geometry.

Electrons entering from the "easy" side sail through the bend; electrons pushed in from the other side hit the trench wall at an unfavorable angle and are mostly reflected back, so the same channel conducts far better in one direction than the other:

I(V) = I₀(exp[V / (n·Vₛ)] − 1)
n_forward ≈ 1.5   (fixed, the easy path)
n_reverse = n_forward + A·(2 − w/w⁏)·10
A = (180° − θ) / 90°   (0 = straight, 1 = sharp 90° kink)

This is a simplified phenomenological stand-in for the full semiclassical Monte-Carlo electron transport used in the device-physics literature, but it reproduces the qualitative behaviour that experiments and simulations agree on:

Bend angle θ — how sharply the channel kinks. θ = 180° is a straight, symmetric channel (no rectification); smaller θ steers electrons more aggressively in one direction and reflects them more strongly in the other, raising the rectification ratio.
Neck width w — the narrowest point of the channel. A wider neck lets more charge leak through even against the "hard" direction (weaker rectification); a narrower neck blocks it more completely.
Bias voltage / AC drive — forward bias (aligned with the easy direction) drives a smooth stream of electrons through; reverse bias mostly bounces them off the kink, visualized as particles piling up and turning back. Switch to AC drive to see the same asymmetric channel rectify a sinusoidal voltage into a mostly one-directional electron flow — the operating principle behind SSD-based zero-bias microwave/THz detectors and rectennas, since there's no junction capacitance to slow it down.

Source electrode Drain electrode Forward-flowing e⁻ Reflected e⁻

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