In the following there will be four selected gate stack types treated, namely, high-k, strained interface, ferroelectric, and electrolytic gate stacks. At first an introduction into high-k gate stacks for amplification and switching purposes will be given. Then, gate stack architectures for storage devices are described. Due to their rising importance over the last years flash-type FETs will be explained in more detail, followed by an examination of techniqes able to introduce strain into the device arcitecture in order to boost the device performance. Afterwards, an introduction into ferroelectric materials and their properties is shown and last electrolytic interfaces and their exploitation in BioFETs will be taken care of.