Improvement of Electrical Properties of Pulsed Laser Crystallized Silicon Films by Oxygen Plasma Treatment

Abstract

Changes in the electrical properties of pulsed laser crystallized silicon films with oxygen plasma treatment were investigated. 50-nm-thick silicon films doped with 7.4 ×10 17 cm -3 phosphorus atoms crystallized by a 308-nm-XeCl excimer laser at an energy density of 400 mJ/cm 2 were treated by 30-W-RF plasma of oxygen gas at 130 Pa at 250°C. The electrical conductivity markedly increased from 6.9 ×10 -5 S/cm (as crystallized) to 10 S/cm by heat treatment for 40 min. Theoretical analysis of the electrical conductivity revealed that the potential barrier height at grain boundaries decreased from 0.32 eV (as crystallized) to almost zero, and that carrier mobility increased from 15 cm 2 /Vs (as crystallized) to 170 cm 2 /Vs.