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Semiconductor structures, low-dimensional systems, quantum phenomena
Doping-dependent nonlinear electron mobility in GaAs|In$_x$ Ga$_{1-x}$ As coupled quantum-well pseudo-morphic MODFET structure
S. R. Panda,
A. Sahu,
S. Das,
A. K. Panda,
T. Sahu Department of Electronics and Communication Engineering, National Institute of Science and Technology, Palur Hills,
Berhampur-761 008, Odisha, India
Abstract:
We analyze the asymmetric delta-doping dependence of nonlinear electron mobility
$\mu$ of GaAs|In
$_x$ Ga
$_{1-x}$ As double quantum-well pseudo-morphic modulation doped field-effect transistor structure. We solve the Schrödinger and Poisson's equations self-consistently to obtain the sub-band energy levels and wave functions. We consider scatterings due to the ionized impurities (IMP), alloy disorder (AL), and interface roughness (IR) to calculate
$\mu$ for a system having double sub-band occupancy, in which the inter-sub-band effects play an important role. Considering the doping concentrations in the barriers towards the substrate and surface sides as
$N_{d1}$ and
$N_{d2}$, respectively, we show that variation of
$N_{d1}$ leads to a dip in
$\mu$ near
$N_{d1}$ =
$N_{d2}$, at which the resonance of the sub-band states occurs. A similar dip in
$\mu$ as a function of
$N_{\mathrm{d}1}$ is also obtained at
$N_{d1}$ =
$N_{d2}$ by keeping (
$N_{\mathrm{d}1}$ +
$N_{d2}$) unchanged. By increasing the central barrier width and well width, the dip in
$\mu$ becomes sharp. We note that even though the overall
$\mu$ is governed by the IMP- and AL-scatterings, the dip in
$\mu$ is mostly affected through substantial variation of the sub-band mobilities due to IR-scattering near the resonance. Our results of nonlinear electron mobility near the resonance of sub-band states can be utilized for the performance analysis of GaAs|InGaAs pseudo-morphic quantum-well field-effect transistors.
Keywords:
asymmetric double quantum wells, GaAs|In$_x$ Ga$_{1-x}$ As structures, nonlinear electron mobility, pseudo-
morphic HEMT structures, resonance of sub-band states. Received: 28.03.2018
Revised: 04.03.2020
Accepted: 04.03.2020
Language: English
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