Electron transport in strained Si inversion layers grown on SiGeoninsulator substrates
Abstract
We show by simulation that electron mobility and velocity overshoot are greater when strained inversion layers are grown on SiGeOninsulator substrates (strained Si/SiGeOI) than when unstrained silicononinsulator (SOI) devices are employed. In addition, mobility in these strained inversion layers is only slightly degraded compared with strained bulk Si/SiGe inversion layers, due to the phonon scattering increase produced by greater carrier confinement. Poisson and Schroedinger equations are selfconsistently solved to evaluate the carrier distribution in this structure. A Monte Carlo simulator is used to solve the Boltzmann transport equation. Electron mobility in these devices is compared to that in SOI inversion layers and in bulk Si/SiGe inversion layers. The effect of the germanium mole fraction x, the strainedsilicon layer thickness, T_{Si}, and the total width of semiconductor (Si+SiGe) slab sandwiched between the two oxide layers, T_{w} were carefully analyzed. We observed strong dependence of the electron mobility on T_{Si}, due to the increase in the phonon scattering rate as the silicon layer thickness is reduced, a consequence of the greater confinement of the carriers. This effect is less important as the germanium mole fraction, x, is reduced, and as the value of T_{Si} increases. For T_{Si}>20 nm, mobility does not depend on T_{Si}, and maximum mobility values are obtained.
 Publication:

Journal of Applied Physics
 Pub Date:
 July 2002
 DOI:
 10.1063/1.1481962
 Bibcode:
 2002JAP....92..288G
 Keywords:

 Boltzmann Transport Equation;
 Electron Mobility;
 Electron Phonon Interactions;
 Electron Transfer;
 Field Effect Transistors;
 Germanium Alloys;
 Insulators;
 Inversions;
 Metal Oxide Semiconductors;
 Mis (Semiconductors);
 Monte Carlo Method;
 Poisson Equation;
 Schroedinger Equation;
 Semiconductor Devices;
 Semiconductors (Materials);
 Silicon;
 Silicon Alloys;
 Soi (Semiconductors);
 Thin Films;
 Transport Properties;
 73.40.Qv;
 73.50.Dn;
 85.30.Tv;
 73.50.Bk;
 85.30.De;
 SolidState Physics;
 Metalinsulatorsemiconductor structures;
 Lowfield transport and mobility;
 piezoresistance;
 Field effect devices;
 General theory scattering mechanisms;
 Semiconductordevice characterization design and modeling