Properties of Semiconductors: Practice Problem & Solution

Solution Explained:

To solve this problem, we apply the core principles of Properties of Semiconductors. Understanding the underlying formula is key to arriving at the correct answer below:

The ratio of electron to hole currents is given by:

$$\frac{I_n}{I_p} = \frac{7}{4}$$

​The ratio of electron to hole concentrations is:

$$\frac{n}{p} = \frac{7}{5}$$

Using the current formula

$I = q n v A$

I=qnvA, the ratio of drift velocities (

$\frac{v_n}{v_p}$

vp​vn​​) can be found as:

$$\frac{I_n}{I_p}=\frac{n{v}_n}{p{v}_p}$$

Substitute the given ratios:

$$\frac{7}{4} = \frac{\frac{7}{5} \cdot v_n}{v_p}$$

Simplifying:

$$\frac{v_n}{v_p}=\frac{5}{4}$$