The free electron concentration profile $n(x)$ in a doped semiconductor at equilibrium is shown in the figure, where the points A, B, and C mark three different positions. Which of the following statements is/are true?

Question

A JK flip-flop has inputs $J = 1$ and $K = 1$.
The clock input is applied as shown. Find the output clock cycles per second (output frequency).

Answer 1

To analyze the given question, we need to understand the behavior of electron currents and electric fields in a semiconductor, specifically focusing on diffusion and drift currents and the direction of electric fields.

The graph represents the free electron concentration profile $n(x)$ at different positions A, B, and C.

Electron Diffusion Current:

Diffusion current occurs due to the concentration gradient of electrons. It flows from regions of high concentration to low concentration.

In the graph, between B and C, the concentration $n(x)$ decreases, indicating a higher concentration at B compared to C. Hence, the electron diffusion current will be directed from B to C.

Electron Drift Current:

Drift current is caused by an electric field acting on the charge carriers.

For the section between B and A, considering typical semiconductor behavior, the electric field should be examined to determine the direction of drift current.

Electric Field Direction:

The electric field in a semiconductor is related to the charge distribution and potential gradient. Typically, in a decreasing concentration region, the electric field points towards lower concentrations.

Thus, between B and C where $n(x)$ decreases, the electric field points from B to C.

Similarly, between B and A, if we have a consistent potential change, the electric field would logically be directed from A to B, indicating the electron drift current is from B to A due to negative charge movement in the opposite direction.

Concluding the analysis with provided statements:

For $x$ between B and C, the electron diffusion current is directed from C to B. True

For $x$ between B and A, the electron drift current is directed from B to A. True

For $x$ between B and C, the electric field is directed from B to C. True

For $x$ between B and A, the electric field is directed from A to B. This is Actually False based on typical assumptions.

Thus, the correct statements are the first three.

The free electron concentration profile \(n(x)\) in a doped semiconductor at equilibrium is shown in the figure, where the points A, B, and C mark three different positions. Which of the following statements is/are true?

The Correct Option is A, B, C

Solution and Explanation

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