Abstract The study examined the effect of phosphorus dopant concentration on mobility of crystalline silicon (c-Si). The study considers different temperature and dopant concentration in relation to its effect on the mobility of the crystalline silicon. The temperature and dopant concentration ranges from lOOK up to SOOK and 10 12 cm- 3 up to 10 20 cm- 3 , respectively. The thesis work is based on simulation study by using existing software called "Mobility Calculator" from a source called PV Light House. The mobility of the crystalline silicon as a function of dopant concentration and temperature are studied in detail. The study indicates that the mobility of phosphorus doped silicon, at different dopant concentration, tends to reduce as the temperature is increased. On the other hand, the mobility of the doped semiconductor, at different temperature, showed different trend as the dopant concentration increases: I) mobility decreased in between 10 15 to 10 for doping concentrations less than10 16 cm- 3 , II) mobility becomes constant as temperature increases 15 cm- 3 , and 111) mobility not significantly affected, almost linear, by increasing the temperature for high doping concentration 10 Furthermore, the total mobility is affected by both lattice and impurity scattering. The two issues, lattice and impurity, dominate one another depending on the doping concentration and temperature, and thus contributed to dependence of mobility, on temperature, in different trend. This seems to indicate that the general trend, mobility verses temperature - and dopant concentration, corresponds to the fundamental theory of doping in semiconductors. The study indicated the effect of doping on the electrical parameters of the semiconductor quantit&tively. Based on the study, as the temperature gets higher, the electron mobility will get lower, since at higher temperature more phonons can interact (collide) with carriers and the concentration of impurity ions and thermally exited ions cancel out each and as result mobility becomes almost constant, that is, the rate of change of mobility is constant. For low doping concentrations, the mobility is almost constant and is primarily limited by phonon scattering. However, for higher doping concentrations the mobility of carrier decreases due to the ionized impurity scattering with the ionized doping atoms. The study has practical implication for tuning the electrical property of phosphorus doped crystalline silicon.

he undersigned hereby certify that they have read and recommend to the College of Science, School of Graduate Studies for acceptance a thesis entitled "Effect of Phosphorus Dopant Concentration on Mobility of Crystalline Silicon" by Yasab Ayele for the partial fulfilment of the requirements for the Degree of Master of Science in Materials Science & Engineering. Advisor: Amare Benor (PhD) Examiners: Dated: October, 2015