On doping `Ge` with a little of `In or Ga` one gets

Options

A. `p`-type semiconductor
B. `n`-type semiconductor
C. insulator
D. rectifier

Explanation

To solve the question regarding the effect of doping germanium (Ge) with indium (In) or gallium (Ga), we can follow these steps:

### Step 1: Understand the Elements Involved
- Germanium (Ge) is a group 14 element, which means it has four valence electrons.
- Indium (In) and Gallium (Ga) are group 13 elements, which means they have three valence electrons.

**Hint:** Identify the group numbers of the elements to understand their electronic configurations.

### Step 2: Analyze the Doping Process
- Doping is the process of adding impurities to a semiconductor to change its electrical properties.
- When we introduce indium or gallium into germanium, these group 13 elements will replace some of the germanium atoms.

**Hint:** Recall that doping modifies the number of charge carriers in the semiconductor.

### Step 3: Determine the Effect of Doping with Group 13 Elements
- Since indium and gallium have three valence electrons, when they replace a germanium atom (which has four), they create a deficiency of one electron.
- This deficiency creates "holes" in the crystal lattice, which can act as positive charge carriers.

**Hint:** Consider how the number of valence electrons affects the creation of holes.

### Step 4: Classify the Type of Semiconductor
- The introduction of holes (positive charge carriers) means that the doped germanium will have an excess of positive charge carriers.
- This type of semiconductor, which has more holes than electrons, is classified as a P-type semiconductor.

**Hint:** Remember the distinction between N-type (extra electrons) and P-type (extra holes) semiconductors.

### Conclusion
- Therefore, doping germanium with a little indium or gallium results in the formation of a P-type semiconductor.

**Final Answer:** On doping germanium (Ge) with a little indium (In) or gallium (Ga), one gets a P-type semiconductor.

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