Electrical Properties of Pulsed Laser Crystallized Silicon Films

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Abstract
Electrical properties of phosphorus-doped laser-crystallized silicon films were investigated. The analysis of free carrier optical absorption revealed that crystalline grains formed at laser energies of 360–375 mJ/cm2had high carrier mobilities of 40–50 cm2/Vs, which were close to that of doped single crystalline silicon. The mobility did not depend on the number of laser pulses. On the other hand, Hall effect measurements showed a marked increase in the carrier mobility of electrical current traversing grain boundaries from 3 to 28 cm2/Vs as the laser energy density increased from 160 to 375 mJ/cm2. The Hall mobility also increased as the number of laser pulses increased, although a single pulse irradiation resulted in a maximum carrier mobility of 15 cm2/Vs. These results suggest that a high laser energy density as well as numbers of multiple pulses are necessary to reduce disordered amorphous states and improve grain boundary properties.