Lecture on Photodetectors and Solar Cells

These flashcards cover essential concepts related to photodetectors and solar cells as discussed in the lecture.

What is the principle governing photodetectors?

Internal photoelectric effect.

What is the band gap energy range for efficient photon absorption in silicon solar cells?

1.1 to 1.4 eV.

What law describes the absorption coefficient in relation to intensity of incident light?

Beer-Lambert's Law.

What is necessary for effective generation of electric current in a solar cell?

Separation of positive and negative charge carriers.

What is the energy gap (Eg) for silicon?

1.12 eV.

What does an anti-reflection coating do in a solar cell?

Reduces reflection of light and increases light absorption.

How does the thickness of a TCO (Transparent Conductive Oxide) layer affect a solar cell?

It must fulfill a minimum thickness requirement for effective conductivity.

What impact does temperature have on the open-circuit voltage (Voc) of a solar cell?

Voc decreases by approximately 1.7 mV for each degree Celsius increase in temperature.

What are the two main processes occurring at the p-n junction of a solar cell?

Diffusion of majority carriers and drift of minority carriers.

What is the significance of the Fermi level in semiconductors?

It indicates the probability of occupancy of energy states and influences electrical properties.

What type of current flows due to minority carriers in a p-n junction?

Drift current.

What happens when excess impurities are introduced into silicon cells exceeding a certain concentration?

The carrier lifetime decreases dramatically due to Auger recombination.

How is the internal potential barrier (Vo) calculated in a p-n junction?

By relating the electron concentrations on both sides through a Boltzmann factor.

What is the role of surface recombination velocity (S) in solar cells?

It measures the efficiency of charge carrier collection at the surface.

What materials are typically used in anti-reflection coatings?

Silicon nitride and silicon dioxide.

What impact does texturing have on silicon solar cells?

It reduces reflection and increases light absorption by creating microscopic surface structures.

What two factors affect the short-circuit current (Isc) in a solar cell?

Generation of carriers by light absorption and collection of those carriers.

What are the effects of series and shunt resistance in a solar cell?

They cause power losses and reduce efficiency.

What is 'Quantum Efficiency' in the context of solar cells?

The ratio of the number of charge carriers collected to the number of incident photons.

What does the Fill Factor (FF) indicate about a solar cell's performance?

It measures the squareness of the IV curve and the maximum obtainable power.

How do optical properties affect the performance of solar cells?

They influence reflection and absorption of light, affecting overall efficiency.

What is the role of minority carriers in photodetection?

They contribute to the drift current across the junction.