Photodiode Quantum Efficiency: Definition, Equation, and Calculator

This page explains the definition of Photodiode Quantum Efficiency. It also provides the equation/formula and a calculator for determining Photodiode Quantum Efficiency.

What is a Photodiode?

• A photodiode is a photodetector that converts light into either current or voltage, an effect known as the photovoltaic effect.
• A DC source is often used to apply a reverse bias to the photodiode, which increases the generated current. This operational mode is called photoconductive mode.
• Photodiodes are used in optical disc drives, digital cameras, and optical switches, among other applications.
• Variations include PIN photodiodes, Avalanche photodiodes, PN Photodiodes, and Schottky Photodiodes.

The figure depicts the symbol of a photodiode and a real-world device from OSRAM.

For more information, refer to the article on Photodiode basics, types, and their operation.

What is Photodiode Quantum Efficiency?

Definition

Quantum efficiency is the fraction of incident photons absorbed by a photoconductor that generate electrons collected at the detector terminal. Simply put, it’s the fraction of incident photons that contribute to the photocurrent.

It is related to responsivity as per the following equation:

Q.E. = 1240 * (Rλ / λ)

Where:

• Rλ = Responsivity in A/W
• λ = Wavelength in nm

Photodiode Quantum Efficiency Calculator and Example

Here’s an example of a Photodiode Quantum Efficiency calculation:

INPUTS: Re = 1e5, Rp = 1.5e5

OUTPUTS: Quantum Efficiency (Q.E.) = 66.66%

Photodiode Quantum Efficiency Equation/Formula

The following equation or formula is used for the Photodiode Quantum Efficiency calculator.