Modulation doping
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Modulation doping is a technique for fabricating semiconductors such that the free charge carriers are spatially separated from the donors. Because this eliminates scattering from the donors, modulation-doped semiconductors have very high carrier mobilities.
History
Modulation doping was conceived in Bell Labs in 1977 following a conversation between Horst Störmer and Ray Dingle,[1] and implemented shortly afterwards by Arthur Gossard. Störmer and Dan Tsui used a modulation-doped wafer to discover the fractional quantum Hall effect.
Implementation
Applications
Field effect transistors
Modulation-doped transistors can reach high electrical mobilities and therefore fast operation.[3] A modulation-doped field-effect transistor is known as a MODFET.[4]
Low-temperature electronics
One advantage of modulation doping is that the charge carriers cannot become trapped on the donors even at the lowest temperatures. For this reason, modulation-doped heterostructures allow electronics to be operated at cryogenic temperatures.
Quantum computing
Modulation-doped two-dimensional electron gases can be gated to create quantum dots. Electrons trapped in these dots can then be operated as quantum bits.[5]