Buffer-dependent mobility and morphology of quantum wells

Buffer influence on AlSb/InAs/AlSb quantum wells

“…Variations in this scale can markedly affect the electron mobility of InAs QWs [8]. As for QW with GaSb buffer, the fluctuant lateral width is 664.1 nm and trench depth is 2.8 nm, which is more close to the variation of GaSb buffer shown in Fig.…”

“…However, the problem has been circumvented using relaxed metamorphic Sb-containing buffers, grown on GaAs substrate. It is well known that GaSb buffer nucleating with AlSb leads to AlSb/InAs/ AlSb quantum wells (QWs) with better transport properties than that with AlSb buffer because of the better buffer surface quality of GaSb than AlSb [6][7][8]. But there is no report in the case of AlSb buffer smoother than GaSb buffer.…”

Limiting scattering processes in high-mobility InSb quantum wells grown on GaSb buffer systems

“…Because λ F varies from 35.8 to 46.0 nm and the possible morphological scattering centers in the horizontal dimension to the well are more than 2 µm in size, which is roughly 60 times λ F , the hillocks act as a slowly varying, large-scale scattering potential for the electrons. This indicates that the TDs and the hillocks [22] in our samples have a negligible effect on the transport properties of the InSb QW.…”

“…All improvements in the crystal structure and electrical transport can be attributed to the growth dynamics of AlSb and GaSb [22] in the first intermediate buffer. The different surface mobility of the Ga and Al adatoms during growth can result in a distinctly different morphology of a sample.…”

High mobility metamorphic AlSb/InAs heterostructures grown on InP substrates

“…Sasa et al [9] have shown that the 2 DEG is located at the InAs channel interface near the Si-delta-doping plane (in our case the upper interface). In this context, the influence of roughness should be minimized by the channel growth but Thomas et al [10] have shown that an important roughness (trenches about 4 nm deep with a characteristic lateral scale of 40 Â 150 nm) is still present using an AlSb buffer even after 15 nm of InAs. So, the large scattering potential at the AlSb/InAs upper interface can explain the poorer low-temperature mobility of our AlSb-based samples.…”