Abstract
We report magnetotransport measurements of InSb/Al1−xInxSb quantum well structures at low temperature (3K), with evidence for 3 characteristic regimes of electron carrier density and mobility. We observe characteristic surface structure using differential interference contrast DIC (Nomarski) optical imaging, and through use of image analysis techniques, we are able to extract a representative average grain feature size for this surface structure. From this we deduce a limiting low temperature scattering mechanism not previously incorporated in transport lifetime modelling of this system, with this improved model giving strong agreement with standard low temperature Hall measurements. We have demonstrated that the mobility in such a material is critically limited by quality from the buffer layer growth, as opposed to fundamental material scattering mechanisms. This suggests that the material has immense potential for mobility improvement over that reported to date.
Highlights
Indium antimonide (InSb) exhibits the lowest reported electron effective mass (m* = 0.014 me) [1] and highest reported roomtemperature electron mobility [1] of any compound semiconductor
The InSb quantum well heterostructures studied were grown by solid source molecular beam epitaxy (MBE) on semi-insulating GaAs substrates
This is in excellent agreement with the maximum mean free path deduced from mobility measurement, and is strongly suggestive that at low temperatures, when phonon effects are reduced, an electron traveling in the quantum well may travel ballistically through a feature until it reaches a boundary, causing a scattering event and limiting the transport lifetime
Summary
Indium antimonide (InSb) exhibits the lowest reported electron effective mass (m* = 0.014 me) [1] and highest reported roomtemperature electron mobility (μe = 78,000 cm V−1 s−1) [1] of any compound semiconductor. These properties make InSb suited to many electronic applications including low power high frequency electronics and quantum device realisation. It is believed that a major scattering mechanism associated with material quality has not been considered previously, with this having a major effect on the mobility behaviour. Considering this additional structural scattering allows for far more reasonable values for standard scattering mechanisms, showing that there is immense potential for mobility improvement in this material
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