What is a photodiode?
A semiconductor diode that produces current when light generates mobile charge carriers within it.
AQA A-level Physics (7408) · 3.13.1.3
Revise AQA A-level Physics (7408) specification point 3.13.1.3, Photodiode (A-level only), with free active-recall flashcards. Flip through the set or review every question and answer below.
1 / 12
What is a photodiode?
A semiconductor diode that produces current when light generates mobile charge carriers within it.
How is a photodiode biased in photoconductive mode?
It is reverse biased.
How does a photodiode produce photocurrent in photoconductive mode?
Its electric field separates light-generated carriers, producing a photocurrent in the external circuit.
How does incident light intensity affect a photodiode’s reverse current?
The magnitude of the reverse current increases as light intensity increases.
What is a photodiode’s dark current?
A small reverse current that can flow without illumination.
What does a photodiode’s current–voltage characteristic show?
How the current depends on the voltage across the photodiode.
What does a family of photodiode current–voltage curves at different illumination levels show?
How illumination changes the reverse current.
What determines the signs of current and voltage on a photodiode characteristic graph?
The graph’s sign convention.
What does a scintillator produce when it absorbs energy from an incident atomic particle?
A brief flash of light, using some of the absorbed energy.
What is the photodiode’s role in a scintillation detector?
It detects the light and converts it into an electrical signal.
What does the electrical signal from a scintillation detector indicate?
That a particle has interacted with the scintillator.
What can the signal size reveal in a suitably calibrated scintillation detector?
Information about the energy deposited by the particle.