Effect of Ge surface termination on oxidation behavior

Liquid-Phase Adsorption of Sulfur on Germanium: Reaction Mechanism and Atomic Geometry

“…As we have discussed in detail before, the sulfur coverage critically depends on the chemical composition of the Ge(100) surface prior to sulfidation, rather than on the time the substrates are immersed into solution. The presence of Ge-oxides (and/or -hydroxides) on the surface, which is often the case after a HF treatment, appears to inhibit the adsorption of sulfur as the O-termination is thermodynamically favored over the S-termination (Ge–O bonds: 659 kJ/mol vs Ge–S bonds: 534 kJ/mol) . This is further supported by our experimental and theoretical findings reported below, which show no evidence for the formation of a chemical bond between the sulfur and oxygen atoms on the surface.…”

Impact of ammonium sulfide solution on electronic properties and ambient stability of germanium surfaces: towards Ge-based microelectronic devices

“…This observation is consistent with the stability reported for sulfur layers formed by H 2 S exposure of Ge surfaces 15 and for S/Ge surfaces prepared in (NH 4 ) 2 S solution. 14 However, it can be seen in Fig. 7 that oxygen adsorption is not completely inhibited on the (NH 4 ) 2 S treated surface, i.e., the amount of oxygen increases with the time the S/Ge surface is exposed to air.…”

“…Remarkably, it has been postulated that the formation of volatile sulfur species, i.e., SO 2 , may be the precursor to sulfur desorption, and hence to a successive degradation of the sulfur layer observed aer long exposure to ambient conditions (several days). 14,49 Even though no signicant loss of sulfur was observed for an exposure duration of 120 minutes, the surface chemistry is modied due to the oxidation of sulfur. This is an important nding as variations in the chemical state of the sulfur atoms are expected to affect the electronic properties of the surface.…”

“…[10][11][12] The resulting sulfur-terminated surfaces exhibit an increased ambient stability compared to clean or hydrogenterminated Ge surfaces, which suggests better chemical passivation. [13][14][15] A signicant degradation of the sulfur layer has been observed aer exposure to ambient conditions for several days. 14 The nature of the underlying mechanisms that eventually initiate sulfur desorption has remained, however, rather speculative so far and the impact of exposure to air on the chemical structure of sulfur has not been investigated.…”

“…[13][14][15] A signicant degradation of the sulfur layer has been observed aer exposure to ambient conditions for several days. 14 The nature of the underlying mechanisms that eventually initiate sulfur desorption has remained, however, rather speculative so far and the impact of exposure to air on the chemical structure of sulfur has not been investigated.…”