Intersubband effects on electron mobility in GaAs/ InxGa1-xAs Quantum well FET with asymmetric doping profiles

• Published in: 2023 IEEE Devices for Integrated Circuit (DevIC) pp. 272 - 276
• Main Authors: Panda, Sangita R., Pradhan, Manoranjan, Sahu, Trinath, Panda, Ajit Kumar
• Format: Conference Proceeding
• Language: English
• Published: IEEE 07-04-2023
• Subjects: asymmetric quantum well; channel conductivity; Conductivity; Electron mobility; Impurities; Integrated circuits; Metals; multisubband electron mobility; QWFET structures; Scattering; scattering rate matrix elements (SRME); Surface waves
• DOI: 10.1109/DevIC57758.2023.10134919

Authors analyze electron mobility, \mu by taking asymmetric doping concentrations, varying nd1 in the substrate barrier and keeping nd 2 constant in the surface barrier. With increase in nd1, \mu increases mostly dominated by ionized impurity (imp-) and alloy disorder (al-) scatterings for lowest subband occupancy and then by imp-scattering only when two subbands are occupied. At the starting of second subband, inter subband scattering triggers, causing drop in \mu. Mobility due to imp scattering (\mu imp ) is governed by intra subband scattering rate while \mu^{\text {al}} and \mu ir are governed by inter subband scattering rates. For well width w=200 \unicode{0x00C5}, \mu enhances from 1.1 \times 10^{5} \mathrm{~cm}^{2} / \mathrm{V} s to 1.4 \times 10^{5} \mathrm{~cm}^{2} / Vs with increase in nd1 (from 0.1 \times 10^{18} \mathrm{~cm}^{-3} to 1.4 \times 10^{18} \mathrm{~cm}^{-3}). At nd1 =1.5 \times 10^{18} \mathrm{~cm}^{-3} second subband starts, leading to considerable drop in \mu and thereafter with further increase in nd1, \mu rises through intersubband effects. As well width increases, the drop in \mu occurs at less value of nd1 and in fact for w=400 \unicode{0x00C5} there is fully double subband occupied. The results of \mu mediated through inter subband effects can help in analyzing the characteristics of the QWFET devices.