Experimental and theoretical analysis of the temperature dependence of the two-dimensional electron mobility in a strained Si quantum well

Abstract

The temperature dependence of the mobility of the two-dimensional electron gas (2DEG) in a silicon quantum well strained by Si 0:7 Ge 0:3 relaxed buffer layer is determined precisely by a mobility spectrum analysis. The 2DEG mobility is 2780 cm 2 /V s at room temperature and, upon cooling, increases continuously to reach l 2DEG ¼ 7:4 Â 10 4 cm 2 =V s at 7 K. A back gate installed on the sample changes the 2DEG concentration n successfully to establish l 2DEG / n 1:4 at the constant temperature T ¼ 10K, implying that the scattering at such low temperature is limited solely by the remote ionized impurity scattering. Based on this finding, theoretical analysis of the temperature dependence of l 2DEG is performed based on the relaxation time approximation using 2DEG wavefunctions and subband structures determined self-consistently and including three major scatterings; by intravalley acoustic phonons, intervalley g-processes of longitudinal optical (LO) phonons, and remote ionized impurities. The calculation included only three fitting parameters, the shear deformation potential (N u ¼ 9:5 eV), LO phonon deformation potential for g-process scattering (D 0 ¼ 9:0 Â 10 8 eV=cm), and sheet density of remote ionized impurities that have been determined by quantitative comparison with our experimental results. The temperature dependence of l 2DEG calculated theoretically show excellent agreement with experimentally determined l 2DEG. V

Domain Walls Conductivity in Hybrid Organometallic Perovskites and Their Essential Role in CH3NH3PbI3 Solar Cell High Performance

“…For qualitative consideration, one could start with considering only one plane-perpendicular electronic subband and neglect possible multiband effects. To evaluate the charge carrier mobility at the domain wall, one should consider several scattering mechanisms including: (i) phonon related intravalley scattering; (ii) phonon related intervalley g-process scattering; (iii) remote ionized impurity scattering, and; (iv) effects of possible interface (domain wall) roughness 29 30 . At low temperatures, the last two contributions should dominate.…”

Intrinsic broadening of the mobility spectrum of bulk n-type GaAs

“…Further developments by several research groups led to what is known as mobility spectrum analysis (MSA), in which the generated spectra are optimized to quantitatively agree with the experimentally derived magnetic field-dependent Hall and resistivity results [2][3][4][5][6][7]. Recently, MSA has been utilized to study carrier transport in a variety of semiconductor nanostructures and devices [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27].…”

Nanoscale Conductive Sheets in Ferroelectric BaTiO3: Large Hall Electron Mobilities at Head-to-Head Domain Walls

“…Obviously, only a fraction of the theoretically derived number of charge carriers is available for electrical transport along the DW, while a decisive part of the bound-charge-compensating electrons is most probably trapped, e.g., as self-trapped small polaron in-gap states, similar to those revealed in head-to-tail DWs of BiFeO 3 . Moreover, the roughness of the DW real structure might have a decisive impact − on the measured mobility and the charge-carrier density values as well because it itself influences the scattering mechanism, creates charged scattering centers, or leads to highly localized electrons with low mobility that do not contribute to the electronic transport. For a clear disentanglement of the several conceivable mechanisms of trapping and scattering by electronic and crystallographic imperfections, which dramatically reduce the charge-carrier density, further elaborate theoretical and experimental efforts are indispensable.…”