Experimental determination of the electron effective masses and mobilities in each dimensionally-quantized subband in an In$_x$Ga$_{1-x}$As quantum well with InAs inserts

HEMT structures with In$_{0.53}$Ga$_{0.47}$As quantum well are synthesized using molecular-beam epitaxy on InP substrates. The structures are double-side Si $\delta$-doped so that two dimensionally-quantized subbands are occupied. The effect of the central InAs nanoinsert in the quantum well on the electron effective masses $m^*$ and mobilities in each subband is studied. For experimental determination of $m^*$, the quantum $\mu_q$ and transport $\mu_t$ mobilities of the two-dimensional electron gas in each dimensionally-quantized subband, the Shubnikov–de Haas effect is measured at two temperatures of 4.2 and 8.4 K. The electron effective masses are determined by the temperature dependence of the oscillation amplitudes, separating the oscillations of each dimensionally-quantized subband. The Fourier spectra of oscillations are used to determine the electron mobilities $\mu_q$ and $\mu_t$ in each dimensionally-quantized subband. It is shown that $m^*$ decreases as the InAs-nanoinsert thickness $d$ in the In$_{0.53}$Ga$_{0.47}$As quantum well and electron mobilities increase. The maximum electron mobility is observed at the insert thickness $d$ = 3.4 nm.