TIME-RESOLVED DECAY OF THE BLUE EMISSION IN POROUS SILICON

The technologically interesting blue emission from porous silicon has been studied using time-resolved photoluminescence. In as-etched sampl es prepared using the standard electrochemical method, the decay time is shown to be extremely fast (tau=0.86 ns). This decay time remains u nchanged from room temperature dawn to 77 K. The porous material givin g the blue emission is unstable and degrades rapidly under UV photoexc itation. A corresponding increase in red intensity with decreasing blu e intensity is observed, demonstrating a correlation between the two t ypes of emission. Under ambient light conditions at room temperature t he material is more stable and remains emissive for a number of days. (C) 1994 American Institute of physics.