Professor Andrew Sternberg of Vanderbilt University delivered this lecture for the Introduction to Radiation Effects Engineering online SCALE course.
Pulse lasers serve as a versatile tool for probing single‑event effects (SEEs) in microelectronic devices destined for space and defense environments, where radiation‑induced transients can jeopardize system reliability. Understanding how controlled optical bursts emulate heavy‑ion strikes addresses the scarcity of broad‑beam ion facilities and provides spatial and temporal precision unavailable from traditional sources. This capability is essential for evaluating the susceptibility of modern integrated circuits to transient charge deposition.
The resource explains that a photon’s energy E=hc/λ (≈ 1240 nm·eV/λ) must exceed the semiconductor band‑gap Eg (1.12 eV for silicon, corresponding to λ ≈ 1107 nm) to generate electron‑hole pairs. It contrasts absorption depths for common laser wavelengths: 532 nm (2.33 eV) yields an 1/e intensity depth of ≈ 1.3 µm, 1064 nm (1.16 eV) penetrates ≈ 0.9 mm, while longer wavelengths such as 1260 nm are essentially transparent (≈ 27 m) unless two‑photon absorption (TPA) occurs. By invoking Beer’s Law I(z)=I0e−αz and the absorption coefficient α, the discussion quantifies exponential intensity decay and demonstrates how high‑intensity, tightly focused, ultrashort pulses (gigawatts cm⁻²) enable TPA‑mediated charge generation at arbitrary depths, overcoming metal‑layer shielding in contemporary devices.
Armed with this knowledge, learners can articulate why pulse lasers are employed for SEE testing, compare the absorption depths of different laser wavelengths in silicon, and apply Beer’s Law to predict photon intensity attenuation within semiconductor substrates. These competencies support the design of precise backside‑illumination experiments, the interpretation of laser‑induced charge deposition, and the translation of optical test results into reliable radiation‑hardening strategies for advanced microelectronics.