Initial stages of the thermal nitridation of the Si(100) surface with NH3 and NO: a surface sensitive study of Si 2p core-level shifts

Mechanisms for NH3 Decomposition on the Si(111)-7 × 7 Surface: A DFT Cluster Model Study

“…Through the recent experimental − and theoretical − investigations, it is now generally accepted that the initial adsorption of NH 3 on the Si(100)-2 × 1 surface gives rise to Si−NH 2 and Si−H products at room temperature, by “capping” the dangling bonds of a SiSi dimer. Successive N−H bond cleavage can occur on elevated temperatures around 600−800 K, accompanied by N insertions and H 2 liberations. − Early theoretical calculations paid attention only to the initial step of NH 3 (g)dissociation. − Several recent calculations − demonstrated the complete NH 3 dissociation over the Si(100)-2 × 1 surface. Such a detailed mechanistic understanding is not yet available for the Si(111)-7 × 7 surface.…”

A Theoretical Study of the Interaction of Ammonia with Silicon Trimer

“…First, the existence of states that resemble physisorption of intact ammonia on the silicon cluster provides important corroboration of experimental observation of intact desorption of ammonia from silicon clusters . This behavior in clusters stands in contrast to most bulk surface studies. − Consideration of frontier molecular orbital arguments helps to rationalize this difference further. The pertinent frontier orbitals in cluster chemistry, particularly for small silicon clusters, show unfavorable energy gaps to allow facile dissociative reactivity of the ammonia.…”

“…The reaction of ammonia on silicon is one example of these differences. For the bulk surface the use of ammonia for chemical vapor deposition (CVD) of silicon nitride and oxynitride films has led to a number of theoretical , and experimental ,− studies. This reaction shows sensitivity to several experimental details, such as surface symmetry and reconstruction, but dissociative chemisorption is regularly evident, unless the experiment is carried out at low temperatures .…”

“…This reaction shows sensitivity to several experimental details, such as surface symmetry and reconstruction, but dissociative chemisorption is regularly evident, unless the experiment is carried out at low temperatures . For small silicon clusters, Jarrold and co-workers found evidence that ammonia dissociates intact, , a result that is different than the preponderance of bulk surface chemistry. − Smalley and co-workers , have also studied this reaction, and there has been some controversy over issues such as magic numbers, cluster sizes that are relatively inert under the reaction conditions obtained. This controversy arises with clusters, notably larger than the trimer we have studied here.…”

Ultra-thin high-quality silicon nitride films on Si(111)

“…Various methods have been employed for the growth of Si 3 N 4 films. Most prominent among them is the exposure of a Si substrate to reactive gases like NH 3 [15][16][17][18][19][20][21][22] and NO [23][24][25] in a wide temperature range. Other methods that have been used are ion bombardment [26,27] and sputter deposition, the latter allowing the growth of thick, amorphous Si 3 N 4 films [28].…”