The accurate measurement of background carrier concentration in short-period longwave InAs/GaSb superlattices on GaSb substrate

In the paper we report on a technology of removing the conducting GaSb substrate with the mechanical thinning and wet etch, and then the electrical measurement of non-intentionally doped long-wavelength Infrared (LWIR) type-II InAs/GaSb superlattices (SLs). The SL structures were made of periodic 15 InAs monolayers (MLs) and 7 GaSb MLs with cutoff wavelengths around 11 mu m. A etch stop layer was grown between the GaSb substrate and SL for substrate removal for no chemical solution exists with enough selectivity between the GbSb and SLs during the wet etch process. After removing the GaSb substrate, the transport properties mearsurement of SLs are performed using temperature dependent from 20 k to 296 k and variable magnetic field Hall measurements. It is found that the LWIR SLs is n-type at the all temperatures. Mealwhile, from the result of the mobility spectrum analysis at 76 k, there are more than one type carrier conducting in the LWIR SLs material.