Velocity fluctuation noise measurements on AlGaAs—GaAs interfaces

In this paper, the experiments undertaken to determine the dc, ac, and noise properties in the hot-electron regime of AlGaAs-GaAs heterojunction interfaces are discussed. With the use of noise temperature data, the diffusion coefficient can be determined as a function of electric field for transport parallel to the AlGaAs-GaAs interface. Two device structures with different characteristics, such as length, fraction of aluminum content, sheet-carrier concentration, etc., are used in the experiments. The experimental results are attributed to the field-dependent charge-transport properties of the quasi-two-dimensional electron gas formed at the interface.