 Complex layered structures of gallium arsenide in combination with aluminium arsenide (AlAs) or the alloy AlxGa1−xAs can be grown using molecular beam epitaxy (MBE) or using metalorganic vapor phase epitaxy (MOVPE).Because GaAs and AlAs have almost the same lattice constant, the layers have very little induced strain, which allows them to be grown almost arbitrarily thick.This allows extremely high performance and high electron mobility HEMT transistors and other quantum well devices.