The depletion region of a P-N diode, under open circuit condition contains

Options

A. Electrons
B. Holes
C. Unmasked immobile impurity ions
D. Impurity atoms

Answer

To solve the question regarding the depletion region of a P-N diode under open circuit conditions, let's break it down step by step.

### Step 1: Understand the Structure of a P-N Junction
A P-N junction diode consists of two regions: the P-type region, which has an abundance of holes (positive charge carriers), and the N-type region, which has an abundance of electrons (negative charge carriers).

**Hint:** Remember that P-type has holes and N-type has electrons.

### Step 2: Identify Charge Carriers in Each Region
In the P-type region, the charge carriers are holes, which are created by doping the semiconductor with acceptor impurities. In the N-type region, the charge carriers are electrons, created by doping with donor impurities.

**Hint:** P-type = holes (positive), N-type = electrons (negative).

### Step 3: Understand the Depletion Region
When the P-N junction is formed, electrons from the N-region diffuse into the P-region and recombine with holes. Similarly, holes from the P-region diffuse into the N-region and recombine with electrons. This recombination leads to the formation of a depletion region, which is devoid of free charge carriers.

**Hint:** Recombination of charge carriers leads to the depletion of mobile charges.

### Step 4: Analyze the Composition of the Depletion Region
In the depletion region, only immobile ions remain. In the P-region, the immobile positive ions (from the acceptor atoms) are left behind after the holes have recombined. In the N-region, the immobile negative ions (from the donor atoms) remain after the electrons have recombined.

**Hint:** The depletion region contains immobile ions, not free charge carriers.

### Step 5: Conclusion
Under open circuit conditions, the depletion region of a P-N diode contains unmasked immobile impurity ions. These ions are the result of the doping process that created the P-type and N-type materials.

**Final Answer:** The depletion region of a P-N diode under open circuit conditions contains unmasked immobile impurity ions.