This Question has been bugging me for sometime. Some semiconductors have direct bandgaps and indirect bandgaps. So what causes a direct bandgap to occur? The physics behind ,why there are direct bandgaps? I collected some data on a dozen compound semiconductors from handbooks (III-Vs, II-VIs and IVs) (35+ compound semiconductors if you count multiple crystalline allotropes of the same material) and performed anova with crystal structure, atomic number & location of constituting elements on the periodic table as variables. I found that the biggest influence on whether a semiconductor has a direct bandgap or indirect bandgap was atomic number of constituting elements and not crystal structure or location of the constituting elements on the periodic table. Could it be because a high atomic number entails a strong nuclear field from the constituting atoms in the unit cell that somehow aligns the conduction and valence bands in momentum space? Any ideas, opinions, relevant papers?

Thanks

This Question has been bugging me for sometime. Some semiconductors have direct bandgaps and indirect bandgaps. So what causes a direct bandgap to occur? The physics behind ,why there are direct bandgaps? I collected some data on a dozen compound semiconductors from handbooks (III-Vs, II-VIs and IVs) (35+ compound semiconductors if you count multiple crystalline phases of the same material) and performed anova with crystal structure, atomic number & location of constituting elements on the periodic table as variables. I found that the biggest influence on whether a semiconductor has a direct bandgap or indirect bandgap was atomic number of constituting elements and not crystal structure or location of the constituting elements on the periodic table. Could it be because a high atomic number entails a strong nuclear field from the constituting atoms in the unit cell that somehow aligns the conduction and valence bands in momentum space? Any ideas, opinions, relevant papers?

Thanks

This Question has been bugging me for sometime. Some semiconductors have direct bandgaps and indirect bandgaps. So what causes a direct bandgap to occur? The physics behind ,why there are direct bandgaps? I collected some data on a dozen compound semiconductors from handbooks (III-Vs, II-VIs and IVs) (35+ compound semiconductors if you count multiple crystalline allotropes of the same material) and performed anova with crystal structure, atomic number & location of constituting elements on the periodic table as variables. I found that the biggest influence on whether a semiconductor has a direct bandgap or indirect bandgap was atomic number of constituting elements and not crystal structure or location of the constituting elements on the periodic table. Could it be because a high atomic number entails a strong nuclear field from the constituting atoms in the unit cell that somehow aligns the conduction and valence bands in momentum space? Any opinions? Did anyone came across a relevant paper?

Thanks

This Question has been bugging me for sometime. Some semiconductors have direct bandgaps and indirect bandgaps. So what causes a direct bandgap to occur? The physics behind ,why there are direct bandgaps? I collected some data on a dozen compound semiconductors from handbooks (III-Vs, II-VIs and IVs) (35+ compound semiconductors if you count multiple crystalline allotropes of the same material) and performed anova with crystal structure, atomic number & location of constituting elements on the periodic table as variables. I found that the biggest influence on whether a semiconductor has a direct bandgap or indirect bandgap was atomic number of constituting elements and not crystal structure or location of the constituting elements on the periodic table. Could it be because a high atomic number entails a strong nuclear field from the constituting atoms in the unit cell that somehow aligns the conduction and valence bands in momentum space? Any ideas, opinions, relevant papers?

Thanks