Editing Quantum efficiency (section)

==Spectral responsivity==
[[responsivity|Spectral responsivity]] is a similar measurement, but it has different units: [[ampere]]s per [[watt]] (A/W); (i.e. how much [[electric current|current]] comes out of the device per unit of incident light [[Power (physics)|power]]).<ref>{{Citation|last1=Gottwald|first1=Alexander|title=7 - Advanced silicon radiation detectors in the vacuum ultraviolet and the extreme ultraviolet spectral range|date=2018-01-01| url=http://www.sciencedirect.com/science/article/pii/B9780081020555000073|work=Smart Sensors and MEMs (Second Edition)|pages=151–170|editor-last=Nihtianov|editor-first=Stoyan| series=Woodhead Publishing Series in Electronic and Optical Materials|publisher=Woodhead Publishing|language=en|isbn=978-0-08-102055-5| access-date=2020-08-19|last2=Scholze|first2=Frank|editor2-last=Luque|editor2-first=Antonio}}</ref> Responsivity is ordinarily specified for monochromatic light (i.e. light of a single wavelength).{{cn|date=February 2024}} Both the quantum efficiency and the responsivity are functions of the photons' wavelength (indicated by the subscript λ).

To convert from responsivity ({{math|''R<sub>λ</sub>''}}, in A/W) to QE<sub>λ</sub><ref>A. Rogalski, K. Adamiec and J. Rutkowski, ''Narrow-Gap Semiconductor Photodiodes'', SPIE Press, 2000</ref> (on a scale 0 to 1):
<math display="block">QE_\lambda=\frac{R_\lambda}{\lambda}\times\frac{h c}{e}\approx\frac{R_\lambda}{\lambda} {\times} (1240\;\mathrm{W \cdot {nm} / A}) </math>
where {{mvar|λ}} is the wavelength in [[nanometre|nm]], ''h'' is the [[Planck constant]], ''c'' is the [[speed of light]] in vacuum, and ''e'' is the [[elementary charge]]. Note that the unit W/A (watts per ampere) is equivalent to V (volts).

===Determination===
<math display="block">QE_\lambda=\eta =\frac{N_e}{N_\nu}</math>
where <math>N_e</math> = number of electrons produced, <math>N_\nu</math> = number of photons absorbed.
<math display="block">\frac{N_\nu}t = \Phi_o \frac{\lambda}{hc}</math>

Assuming each photon absorbed in the depletion layer produces a viable electron-hole pair, and all other photons do not,
<math display="block">\frac{N_e}t = \Phi_{\xi}\frac{\lambda}{hc}</math>
where ''t'' is the measurement time (in seconds), 
<math>\Phi_o</math> = incident optical power in watts, 
<math>\Phi_{\xi}</math> = optical power absorbed in depletion layer, also in watts.