Layer-by-layer removal of GaAs(110) by bromine

Abstract

Dissociative electron attachment of CH3Br on GaAs(110) by thermalized photoexcited substrate electrons

Photochemistry in CH3I Adlayers on TiO2(110) Studied with Postirradiation Thermal Desorption

“…In addition, the energetics for dissociation is less favorable for TiO 2 (110) compared to the metal and GaAs surfaces due to a much weaker halide-surface interaction. On metallic surfaces, halogen atoms are chemisorbed so strongly that they desorb as metal halides (Cl and Br) or atomically (I) at very high temperatures (>800 K). ,, On the GaAs surface, halogen atoms (Cl and Br) form halide compounds with the surface gallium atoms and desorb as gallium halides at a temperature of ∼600 K (surface etching). , By comparison, the iodine atoms on TiO 2 (110) are bound very weakly and desorb as I 2 at ∼200 K. Thus, after electron attachment to CH 3 I, the driving force for a transiently anionic CH 3 I species to dissociate the C−I bond will be much smaller on TiO 2 (110) than on metal or GaAs surfaces.…”

“…21,42,48 On the GaAs surface, halogen atoms (Cl and Br) form halide compounds with the surface gallium atoms and desorb as gallium halides at a temperature of ∼600 K (surface etching). 49,57 By comparison, the iodine atoms on TiO 2 (110) are bound very weakly and desorb as I 2 at ∼200 K. Thus, after electron attachment to CH 3 I, the driving force for a transiently anionic CH 3 I species to dissociate the C-I bond will be much smaller on TiO 2 -(110) than on metal or GaAs surfaces.…”

Coverage-dependent etching pathways for Br–GaAs(110)

“…In all cases, the impingement rate from our electrochemical cell, with a cell current of 5 A and a geometric factor of 7.5%, is about 2.6ϫ10 Ϫ3 Br atoms per substrate atom per second. 3 As a result, the removal mode is layer-by-layer. 1͑a͒ while the relatively low loss appears as pits (ϳ10 11 pits/cm 2 ).…”

“…1 Atomic-level etching studies using scanning tunneling microscopy ͑STM͒ have shown that thermal etching with continuous halogen exposure can result in a variety of different morphologies. 3 In particular, if a surface exposed to Br 2 at 300 K is annealed at 700 K, the morphology is characterized by single-layer-deep etch pits, with the second layer remaining intact. 2 For the fabrication of quantum devices with strictly controlled layer thicknesses, it is essential that material be removed in a layer-bylayer fashion.…”

Synergetic effect enhanced photoelectrocatalysis

“…Bromine (Br 2 ) is a strong oxidant used in organic synthesis, pollutant degradation and semiconductor etching, which is poisonous and dangerous for storage and transport. [12][13][14][15][16] The aim of this work is to provide a green method for the generation of Br 2 in situ. The first photoelectrochemical reaction system (Fig.…”