Air-stable Cl-terminated Ge(111)

Abstract

It is shown that an air-stable Ge(111) surface can be made by wet chemical HCl treatment in ambient atmosphere. X-ray photoelectron spectroscopy (XPS) and photon electrical field polarization-dependent Cl K-edge x-ray absorption spectroscopy (XANES) were used to study the chemical structure and the physical orientation of chemisorbed Cl. It is found that Cl forms a monovalent bond with the Ge(111) dangling bond (DB) along 〈111〉 surface normal. The stability of HCl-treated Ge(111) is attributed to the surface DBs being terminated by monochloride. Thermodynamics are found to be the governing force in the Ge–HCl reaction processes.

1-Dodecanethiol based highly stable self-assembled monolayers for germanium passivation

“…The corresponding high resolution result for Cl 2p in Fig. 3e could be fitted into Cl 2p 3/2,1/2 and Ge 3s plasmon peaks [37].…”

Ultrafast Hot-Carrier Dynamics at Chemically Modified Ge Interfaces Probed by SHG

“…This procedure is reported to result in a monolayer of Clterminating Ge(111). 9,23 SHG Experimental Setup. The SHG experiments were performed with 800-nm, ∼100-fs, 76-MHz Ti:sapphire oscillator (Coherent Mira Seed) as described elsewhere.…”

Surface Termination and Roughness of Ge(100) Cleaned by HF and HCl Solutions

“…A similar conclusion has been drawn by Lu for Ge(111) surfaces. 7 However, unlike Ge(111) surfaces which only form Ge monochloride, 7 Ge(100) surfaces in our study have both monochloride and dichloride, which is not very surprising since each Ge(100) surface atom has two dangling bonds. These Ge chlorides can be completely removed by 30 min vacuum annealing at 400 o C. The surface termination difference between HF etching and HCl etching can also be explained by the etching mechanism.…”

“…Although Si surface cleaning and passivation have been extensively studied, [1][2][3] only recently has some research been done on Ge surfaces. [4][5][6][7] Conventional XPS results show that HF etching removes Ge oxide and carbon contamination significantly, 4 and HCl etching leads to a chlorine terminated Ge (111) surface, which only forms Ge monochloride. 7 However, it is difficult to probe the details of the chemical nature of treated surfaces and quantify the surface termination and cleanness with conventional XPS, because of its limited surface sensitivity and resolution.…”

“…[4][5][6][7] Conventional XPS results show that HF etching removes Ge oxide and carbon contamination significantly, 4 and HCl etching leads to a chlorine terminated Ge (111) surface, which only forms Ge monochloride. 7 However, it is difficult to probe the details of the chemical nature of treated surfaces and quantify the surface termination and cleanness with conventional XPS, because of its limited surface sensitivity and resolution. In addition, little attention has been paid to the HF concentration, which turns out to be an important factor in the surface hydrogen passivation.…”