Electron transport in Si/SiGe modulation-doped heterostructures using Monte Carlo simulation

Abstract

The electron transport in the two-dimensional gas formed in tensile-strained Si 1-x Ge x /Si/Si 1-x Ge x heterostructures is investigated using Monte Carlo simulation. At first the electron mobility is studied in ungated modulation doped structures. The calculation matches very well the experimental results over a wide range of electron density. The mobility typically varies between 1100 cm 2 /Vs in highly-doped structures and 2800 cm 2 /Vs at low electron density. The mobility is shown to be significantly influenced by the thickness of the spacer layer separating the strained Si channel from the pulse-doped supply layers. Then the electron transport is investigated in a gated modulation-doped structure in which the contribution of parasitic paths is negligible. The mobility is shown to be higher than in comparable ungated structures and dependent on the gate voltage, as a result of the electron density dependence of remote impurity screening.

Electron effective mobility in strained-Si/Si1−xGex MOS devices using Monte Carlo simulation

“…The biaxial tensile strain introduces splitting of degenerate bands [1] which results, for both electrons and holes, in smaller in-plane conduction mass and reduced intervalley scattering thereby yielding improved carrier velocity. In the case of electrons this effect has been clearly shown from mobility measurement and calculation in SiGe-Si-SiGe quantum wells [2][3][4] and it has been used for designing high-performance MODFET with low noise figure and high cut-off and maximum oscillation frequencies [5][6]. Now efforts are made to transfer this advantage in CMOS technology on either bulk or insulating substrate [7][8][9][10].…”

“…According to the gate bias, the 1D Poisson's equation is solved in the MOS capacitor prior to the Monte Carlo computation which is then made under frozen vertical field and uniform lateral driving field. This non-self-consistent approach may include quantization effects through coupling to 1D Schrödinger's equation [4]. That is why quantization is not taken into account in this work.…”

Effect of electric field on low temperature multisubband electron mobility in a coupled Ga0.5In0.5P/GaAs quantum well structure

“…1͒. This leads to a sharp enhancement in B 11 imp ͑the value of B 11 imp near ͉F͉ =9 kV/ cm could not be shown in Fig. 6 as it is beyond the scale͒ thereby reducing 1 imp to zero ͑Fig.…”

“…7͒. The variation in B 11 IR mainly depends upon the changes in the amplitudes of 0 ͑z͒ and 1 ͑z͒ at the interface planes I 1 and I 3 mediated by the dielectric screening matrix. Regarding the variation in B 00 imp/IR in Figs.…”

“…Attempts have also been made to study carrier mobility in different quantum well structures by carrying out Monte Carlo simulation. [9][10][11][12] However, to the best of our knowledge, the study of the effect of electric field on multisubband electron mobility, which very much relies on the intersubband interactions, has not previously been reported.…”