# Does doping affect resistivity?

## Does doping affect resistivity?

The total dopant concentration is exactly that: it is the total concentration of dopant atoms within the semiconductor. As such, these ‘excess’ dopant atoms do not contribute to the resistivity (or conductivity) of the semiconductor. The total dopant concentration is determined by a SIMS measurement.

**How does semiconductor resistivity change with dopant concentration?**

Taken a doped semiconductor at high impurity concentration such that the impurity states are extended in nature, as we lower the temperature, resistivity show weak temperature dependence i.e. very small increase of resistivity with decrease in temperature.

### How do you calculate the conductivity of doped silicon?

The conductivity of a semiconductor is given by the expression, σ=neμe+peμh, where μe is the electron mobility, μh is the hole mobility, and e is the elementary charge. Generally the mobilities decrease with increasing temperature and doping concentration.

**How is dopant density calculated?**

As intrinsic electron (hole) density is usually low at room temperature, carrier density of a typical doped semiconductor is determined by the doping densities, such that n ≈ Nd, for n-type doping and p ≈ Na for p-type doping, where Nd and Na are electron and hole doping densities, respectively.

#### Which conductor has highest resistivity?

The correct answer is option 1 i.e Mercury. The resistivity of a material is the resistance of a wire of that material of unit length and unit cross-sectional area. Resistivity, commonly symbolized by the letter ρ (rho). The unit for resistivity is the ohm-meter.

**Which has higher resistivity Ge or Si?**

Ge has energy band gap of 0.72ev and Si has energy band gap of 1.12ev. So Ge has higher conductivity. Answer: Germanium has lower energy band gap than that of the silicon.

## How does the resistivity of a doped semiconductor vary with temperature?

Resistivity first decreases with increase in temperature(0K-300K) and then increases with increase in temperature(300K-Curie Temperature). After curie temperature, extrinsic semiconductor behaves as a intrinsic semiconductor and at temperature greater than curie temperature, resistivity again starts decreasing.

**What is heavily doped and lightly doped?**

In most transistors, emitter is heavily doped. Its job is to emit or inject electrons into the base. These bases are lightly doped and very thin, it passes most of the emitter-injected electrons on to the collector. The collector is so named because it collects electrons from base.

### What is the resistivity of silicon?

Resistivity and Temperature Coefficient at 20 C

Material | Resistivity ρ (ohm m) | Ref |
---|---|---|

Constantan | 49 | 1 |

Carbon* (graphite) | 3-60 | 1 |

Germanium* | 1-500 | 1 |

Silicon* | 0.1-60 | 1 |

**What is resistivity equation?**

Resistivity, commonly symbolized by the Greek letter rho, ρ, is quantitatively equal to the resistance R of a specimen such as a wire, multiplied by its cross-sectional area A, and divided by its length l; ρ = RA/l. The unit of resistance is the ohm.

#### What does a dopant do?

dopant, any impurity deliberately added to a semiconductor for the purpose of modifying its electrical conductivity. The most commonly used elemental semiconductors are silicon and germanium, which form crystalline lattices in which each atom shares one electron with each of its four nearest neighbours.