Problem 16 - Chemistry Central Science

Question

If you want to dope GaAs to make a p-type semiconductor with an element to replace As, which element(s) would you pick?

Step-by-Step Solution

Answer

To dope GaAs and make a p-type semiconductor by replacing As, you should pick an element from group 14 (IV) of the periodic table, which has one fewer valence electrons compared to As from group 15 (V). The best choices for doping GaAs to create a p-type semiconductor are Silicon (Si) or Germanium (Ge), as they are common and have similar properties to semiconductor materials.

Step 1: Understand the concept of p-type semiconductor

A p-type semiconductor is formed by adding a dopant element that has an extra valence electron compared to the original element in the semiconductor. When this impurity element is added, it forms holes (positively charged carriers) in the semiconductor material. The dopant element must be from the same group in the periodic table but with one fewer valence electron than the replaced element.

Step 2: Determine the group number and valence electrons of As

First, look at the periodic table to find the group number and valence electrons of As (Arsenic). As is found in group 15 (also known as group V or VA), and elements in this group have 5 valence electrons.

Step 3: Select the appropriate element to replace As

Now that we know As is from group 15, we need to find an element from a group with one less valence electron (4 valence electrons). This means we need to look for an element in group 14 (also known as group IV or IVA) of the periodic table. The elements present in group 14 are C (Carbon), Si (Silicon), Ge (Germanium), Sn (Tin), and Pb (Lead).

Step 4: Choose the best element(s) to dope GaAs

The best choices for doping GaAs to create a p-type semiconductor would be to use Si (Silicon) or Ge (Germanium), as these elements are common and have similar properties to the semiconductor materials. Doping GaAs with Si or Ge will provide holes (positively charged carriers) and render the semiconductor p-type.