Gate bias controlled charge distribution in the subbands of In0.29Al0.71As/In0.3Ga0.7As modulation doped heterostructures

Publisher Website
Google Scholar
Abstract
The gate voltage dependent charge distribution within the quantum wells of modulation δ‐doped In0.29Al0.71As/In0.3Ga0.7As heterostructures, grown by molecular beam epitaxy and fabricated into front‐gated, six‐arm, Hall bar configurations, were evaluated by means of resistivity, Hall effect, and Shubnikov–de Haas (SdH) oscillatory magnetoresistance measurements. δ‐doping the barrier layer with Si to 6×1012/cm2 leads to an apparent electron density, as obtained from Hall measurement made at 1.6 K, ns=2.65×1012/cm2. The SdH spectra exhibit a gate voltage‐dependent transition from one subband to two subbands and the total electron density is in good agreement with that obtained from the Hall data. From a fast Fourier transform of the SdH data and low field magnetoresistance measurements the electron densities and mobilities of the two subbands at Vg=0 were found to be ns1=2.39×1012 cm−2, μ1=21 800 cm2/V s and ns2=3.96×1011 cm−2, μ2=16 000 cm2/V s, respectively.