Rapid thermal annealing of size-controlled Si nanocrystals: Dependence of interface defect density on thermal budget

Abstract

Photoluminescence properties of size-controlled Si nanocrystals (NCs) formed by various annealings have been studied in detail. The thermal treatments involve rapid thermal annealing (RTA, 10 to 180 s) as well as conventional tube furnace annealing (1h) at 1100 °C. Whereas the photoluminescence (PL) peak positions and the TEM images indicate only minor changes in NC size, the PL intensity varies over more than two orders of magnitude. A correlation between the total thermal budget applied by the different annealing treatments and the PL intensity is demonstrated. In addition, the PL improvement of interface defect passivation by post-annealing in H2 ambient is investigated. RTA with H2 passivation is not able to achieve the PL intensity and NC interface quality of conventionally annealed and passivated samples. The combination of these results with our previous electron spin resonance studies allows to estimate the interface defect densities. Tube furnace annealed samples after H2 treatment have less than 2% defective NCs. In contrast, more than 95% defective NCs are assumed for a 180 s RTA.