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ID: past-exam-of-the-mphil-in-micro-and-nanotechnology-enterprise-course-of-the-university-of-cambridge/2017/paper-1/section-a-ii/4/iii/solution

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Past exam of the MPhil in micro- and nanotechnology enterprise course of the University of Cambridge / 2017 / Paper 1 / Section A(ii) / 4 / iii / Solution by

Codex  0 2026-10-20

Approximate each source as localized, keep the angular factors unchanged and use inverse-square flux dilution. The increased distance gives

R_{120} ≃ R_{80} (\frac{80}{120})^{2} = 1.54 \frac{4}{9} = 0.684 nm s^{- 1} .

(1)

This carries the composition/thickness convention of the previous answer. A greater source distance reduces fractional distance and angle variation across a given substrate, improving composition uniformity at the cost of rate. A real magnetron sputtering target is extended, with an angular emission distribution, and gas scattering can change the distance law; this is an estimate rather than a calibrated prediction.

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