Strain-induced changes to the electronic structure of germanium

Density functional theory calculations (DFT) are used to investigate the strain-induced changes to the electronic structure of biaxially strained (parallel to the (001), (110) and (111) planes) and uniaxially strained (along the 001], 110] and 111] directions) germanium (Ge). It is calculated that a moderate uniaxial strain parallel to the 111] direction can efficiently transform Ge to a direct bandgap material with a bandgap energy useful for technological applications.