Luminescent Si nanocrystals imbedded in amorphous SiO2 and Si3N4 networks have been prepared using an approach based on deposition of Si-rich Si–O and Si–N films by ultrahigh vacuum-chemical vapor deposition reactions of the single-source precursors O(SiH3)2 and N(SiH3)3 respectively. The film growth is conducted on Si (100) at temperatures of 750–850 °C and at extremely high rates of 20–30 nm per min with complete hydrogen elimination. Rapid thermal annealing of the as-deposited films at 1100–1200 °C for 30–60 s generates Si nanocrystals with tunable sizes, discrete shapes, and uniform distributions. The phase, composition, and microstructure of the films are characterized by a variety of analytical techniques including high-resolution electron microscopy. The room temperature photoluminescence (PL) is blueshifted substantially with respect to pure Si and appears to be independent of the Si3N4 and SiO2 dielectric medium. The PL energy increases with decreasing crystal size in accordance with quantum confinement concepts. The key aspects of this approach include the use of completely inorganic (C–H free) and volatile siloxanes and silyl amines with built-in Si–N and Si–O atomic arrangements that allow stoichiometric control at the atomic level leading to formation of highly homogeneous crystallite profiles with adjustable densities and sizes throughout the amorphous matrix.

No abstract

CoSi 2 structures were formed by focused ion-beam implantation. Patterned silicide lines with dimensions down to 150 nm were produced on (100) silicon. The process involved the ion implantation of 200 keV As++ through a cobalt (34 nm)/oxide (∼2 nm) thin film structure. The thin oxide at the Si/Co interface acted as a selective reaction barrier. Ion-beam mixing disrupted the oxide layer to allow silicidation to proceed during subsequent rapid thermal anneal treatments. Reactions were inhibited in nonimplanted areas. A threshold dose of 3×1015 cm−2 was required for process initiation. Electrical measurements resulted in resistivities ranging from 15 to 30 μΩ cm.

Buried single CdTe/CdMnTe quantum dots realized by focused ion beam lithography Appl. Phys. Lett. 75, 956 (1999); 10.1063/1.124565Focused ion-beam structuring of Si and Si/CoSi 2 heterostructures using adsorbed hydrogen as a resistRecently several new approaches have been proposed to manufacture silicide structures using mask-less techniques. We have developed a new technique for direct patterning and formation of cobalt silicide structures using focused ion-beam ͑FIB͒ implantation. Utilizing the effects of ion-beam mixing and properties of thin barrier oxides, silicide lines with dimensions down to 170 nm were produced on ͑100͒ silicon substrates using the FIB. The process involves the ion implantation of 200 keV As ϩϩ through a cobalt thin film. A thin ͑ϳ2 nm͒ oxide ͑SiO x ͒ at the Si/Co interface acts as a selective reaction barrier. Ion-beam mixing was instrumental in fracturing of the oxide layer, thereby allowing the silicidation reaction to proceed across the boundary during subsequent rapid thermal anneal treatments. Diffusion controlled reactions advanced rapidly in the implanted areas, while it is inhibited elsewhere. A threshold dose of 3ϫ10 15 cm Ϫ2 was required for process initiation. Four-terminal resistance test structures were formed for electrical measurements. Reported resistivity was in the range of 12 to 23Ϯ1 ⍀ cm.

No abstract