How to Solve Numerical Problems on Mobility and Current Density in Semiconductors

TL;DR

To solve numerical problems on mobility and current density in semiconductors, use the formula σ = n * e * (μe + μh) for intrinsic materials, where n is the carrier density. Understand that intrinsic semiconductors have equal numbers of electrons and holes, while extrinsic semiconductors require adjustments for impurity levels and their effects on conductivity and mobility.

Transcript

hello friends in today's class we'll be solving numericals on mobility and current density they are very easy numericals and be sure it can give you very good marks in your exams the first question reads as calculate the electron and hole concentration in intrinsic silicon at room temperature if its electrical conductivity is 4 into 10 is to minus ... Read More

Key Insights

• ❓ The conductivity and resistivity of semiconductors can be related using the formula sigma = 1/rho.
• 🕳️ Intrinsic semiconductors have an equal number of electrons and holes.
• 😑 Impurity levels can affect the performance of semiconductors and can be expressed as parts per million (ppm).
• 🫀 The number of atoms in a given volume of silicon can be calculated using Avogadro's number, density, and atomic weight.
• 🏑 The mobility of carriers determines how easily they can move under the influence of an electric field.
• ✋ Intrinsic semiconductors have a higher resistivity compared to extrinsic semiconductors.
• ❓ Mobility is inversely proportional to resistivity.

Questions & Answers

Q: How do you calculate the electron and hole concentrations in intrinsic silicon at room temperature?

The electron and hole concentrations can be calculated using the formula mune = sigma_in, where sigma_in is the total conductivity of the intrinsic semiconductor.

Q: How do you calculate the intrinsic carrier density in a semiconductor?

The intrinsic carrier density can be calculated by dividing the conductivity (sigma) by the sum of the mobilities of electrons and holes, and the elementary charge (e).

Q: How do you calculate the resistivity of an intrinsic semiconductor?

The resistivity of an intrinsic semiconductor can be calculated by taking the reciprocal of the product of the carrier density, elementary charge, and the sum of the mobilities of electrons and holes.

Q: How do you calculate the mobility of electrons in copper?

The mobility of electrons in copper can be calculated using the formula mu = 1/(nerho), where n is the number of electrons per unit volume and rho is the resistivity of copper.

Summary & Key Takeaways

• The video solves numerical problems involving the calculation of electron and hole concentrations in intrinsic silicon at room temperature.

• It also addresses the calculation of intrinsic carrier density and resistivity in both intrinsic and extrinsic semiconductors.

• The video concludes with solving problems regarding impurity levels in silicon and calculating the mobility of electrons in copper.