Electron concentrations and mobilities in AlSb/InAs/AlSb quantum wells

Abstract

We present data on the electron concentrations and mobilities in deep (≊1.3 eV) AlSb/InAs/AlSb quantum wells grown by molecular-beam epitaxy. High electron sheet concentrations of the order 1012 cm -2, found in the not-intentionally doped wells, indicate the presence of a deep donor in the AlSb barriers. Typical mobilities are between 22 000 and 28 000 cm2/V s at room temperature, increasing with decreasing temperature, and leveling out below 50 K at values between 175 000 and 330 000 cm2/V s. The temperature-independent low-temperature mobilities indicate a nonthermal scattering mechanism, possibly interface roughness scattering. Under illumination the wells exhibit a strong negative photoconductivity, which is explained as a natural consequence of the band structure of the wells.