Electron mobility and drift velocity in selectively doped InAlAs/InGaAs/InAlAs heterostructures

An increase in the electron mobility and drift velocity in high electric fields in quantum wells of selectively doped InAlAs/InGaAs/InAsAs heterostructures is obtained experimentally via controlling the composition of semiconductors forming the interface. The electron mobility at the interface in the In$_{0.8}$Ga$_{0.2}$As/In$_{0.7}$Al$_{0.3}$As metamorphic structure with a high molar fraction of In (0.7–0.8) is as high as 12.3 $\times$ 10$^3$ cm$^2$ V$^{-1}$ s$^{-1}$ at room temperature. An increase in the electron mobility by a factor of 1.1–1.4 is attained upon the introduction of thin (1–3 nm) InAs layers into a quantum well of selectively doped In$_{0.53}$Ga$_{0.47}$As/In$_{0.52}$Al$_{0.48}$As heterostructures. A maximal drift velocity attains 2.5 $\times$ 10$^7$ cm/s in electric fields of 2–5 kV/cm. The threshold field $F_{\mathrm{th}}$ for the intervalley $\Gamma$–$L$ electron transfer (the Gunn effect) in the InGaAs quantum well is higher than in the bulk material by a factor of 2.5–3. The effect of two- to threefold decrease in the threshold field $F_{\mathrm{th}}$ in the InGaAs quantum well is established upon increasing the molar fraction of In in the InAlAs barrier, as well as upon the introduction of thin InAs inserts into the InGaAs quantum well.