Pressure dependence of the energy gaps in AgGaSe2 and AgGaS2.

The optical absorption edge of AgGaSe₂ and AgGaS₂ single crystals was measured as a function of hydrostatic pressure up to 30 GPa. in a gasketed diamond anvil cell. Both materials have several structural phase transitions in this pressure range and it has been established that the orthorhombic and tetragonal phases of AgGaSe₂ and AgGaS₂ at 300 K are indirect gap semiconductors.