Demonstration of interface-scattering-limited electron mobilities in InAs/GaSb superlattices

The in-plane transport in InAs/GaSb type-II superlattices (SLs) is a sensitive indicator of SL growth quality and of the eventual performance of devices made from these materials. The in-plane mobility of electrons that move predominantly in the InAs layer is affected by a number of intrinsic and extrinsic scattering mechanisms, including interface roughness scattering (IRS). The hallmark of classic IRS-limited transport in SLs and quantum wells is the sixth power dependence of mobility on layer width. While IRS-limited transport was demonstrated in a number of SL and quantum well systems, it has never been demonstrated in the important InAs/GaSb SL material. In this paper, we perform temperature dependent Hall effect measurements on a series of InAs/GaSb SLs with a fixed GaSb layer width and a variable InAs layer width d. The low temperature (10 K) in-plane electron mobilities mu as a function of d behave as mu proportional to d(6.20), which follows the classic sixth power dependence expected from theory. At the same time, the dominance of the IRS-limited transport indicates that our samples are less affected by other scattering mechanisms, so that mobility measurements are another indicator of sample quality.