Table 1.

Summary of parameters used to characterise photodetectors (PDs). Coupling factors and wavelength dependence of all quantities are omitted for clarity of notation.

Quantity	Symbol	Definition a	Units
External Quantum Efficiency	${\eta }_e$, EQE	$(I_{ph}/q)/{\varphi }_{in}$	%
Internal Quantum Efficiency	${\eta }_i$, IQE	$(I_{ph}/q)/{\varphi }_{abs}$	%
Operating Bandwidth	$\Delta f$	—	$\mathrm{Hz}$
Gain	G	$\left(\mu \tau E\right)/L$	-
Responsivity	$\mathfrak{R}$	$I_{ph}/P_{opt}$	A/W (V/W)
Noise Equivalent Power	NEP	$S_n/\mathfrak{R}$	W$/\sqrt{\mathrm{Hz}}$
Specific Detectivity	$D^{☆}$	${(A\Delta f)}^{0.5}/\mathrm{NEP}$	cm$\sqrt{\mathrm{Hz}}$/W
Linear Dynamic Range	LDR	$10\times {log}_{10}\left(P_{sat}/\mathrm{NEP}\right)$	dB

^a$I_{ph}=$ Measured photocurrent, ${\varphi }_{in}=$ Incident photon flux, ${\varphi }_{abs}=$ Absorbed photon flux, $P_{opt}={\varphi }_{in}/S=$ Incident optical power density, $A=$ Device area, $S_n=$ Noise spectral density, $P_{sat}=$ Saturation power, $L=$ channel length, $\tau =$ lifetime of photoexcited carriers, $E=$ electric field.