Heat Treatment with High-Pressure H2O Vapor of Pulsed Laser Crystallized Silicon Films

Abstract

Improvement of electrical properties for 7.4 ×1017 cm-3 phosphorus-doped pulsed laser crystallized silicon films of 50 nm thickness formed on quartz glass substrates was achieved by heat treatment with high-pressure H2O vapor. The electrical conductivity was increased from 1.3 ×10-5 S/cm (as-crystallized) to 2 S/cm by annealing at 270°C for 3 h with 1.3 ×106 Pa H2O vapor. The spin density of undoped laser crystallized silicon films was reduced from 1.6 ×1018 cm-3 (as-crystallized) to 1.2 ×1017 cm-3 by annealing at 310°C for 3 h with 1.3 ×106 Pa H2O vapor. Theoretical analysis revealed that the potential barrier height at grain boundaries decreased from 0.3 eV (as-crystallized) to 0.002 eV. High-pressure H2O vapor annealing offer the possibility of reducing the density of defects states through oxidation of the defects at low temperature.