Surface electronic structure of clean and hydrogen-chemisorbedSixGe1

Abstract

The surface electronic states of clean and hydrogen-terminated Si x Ge 1Ϫx surfaces were studied with angleresolved ultraviolet photoelectron spectroscopy ͑ARUPS͒. A series of strained and relaxed Si x Ge 1Ϫx alloys were grown on Si͑100͒ wafers using electron-beam evaporation in an ultrahigh-vacuum molecular-beamepitaxy chamber. The growth was followed by in situ hydrogen-plasma exposure to obtain H-terminated surfaces. After alloy film growth, a double domain 2ϫ1 reconstruction was observed for the series of clean Si x Ge 1Ϫx alloys. A diffuse double domain 2ϫ1 reconstructed surface was obtained after the H-plasma exposure, which implies that the Si͑Ge͒-H monohydride domains are smaller than the surface terraces. The diffuse peaks were attributed to disorder and incoherence in the H termination rather than a change of the terrace structure. He I ͑21.21 eV͒ and Ne I ͑16.85 eV͒ resonance lines were employed to identify the surface states or resonances and bulk states of all samples described in this paper. ARUPS spectra of the series of clean and H-terminated Si x Ge 1Ϫx alloys were obtained as a function of emission angle along the ͓010͔ direction. From measurements of the series of clean Si x Ge 1Ϫx alloy surfaces the surface states or resonances due to the dangling bond and the back bond were identified and found to disperse downward from ⌫ to J ab Ј . A nondispersive hydrogen-induced surface state or resonance was observed from the series of H-terminated Si x Ge 1Ϫx alloy surfaces. The electron affinities of the series of clean and H-terminated Si x Ge 1Ϫx alloy surfaces were also measured using ARUPS. The electron affinity of the Si͑100͒ surface was found to be 3.83 eV and those of strained and relaxed Si x Ge 1Ϫx ͑100͒ surfaces ranged from 3.87 to 4.05 eV. The electron affinity of clean and H-terminated surfaces exhibited the same values.

Electronic structure of monolayer and double-layer Ge on Si(001)

“…As a different approach, Ku and Nemanich performed an ARPES study on the Si x Ge 1Ϫx alloy surfaces grown on a Si͑001͒ surface. 26 In that study, a dangling-bond state ͑A͒ and a back-bond state ͑D͒ were observed on both Si 0.2 Ge 0.8 and Si 0.8 Ge 0.2 alloy surfaces ͑the DD 2ϫ1 surfaces͒ along the ͓010͔ azimuth with proximal dispersions to those of the clean Si(001)2ϫ1 surface. That result is thus fully consistent to the present observation.…”

Self-consistent solution of Schrödinger–Poisson equations in a reverse biased nano-scale $$p$$ p - $$n$$ n junction based on $$\hbox {Si/Si}_{0.4}\hbox {Ge}_{0.6}/\hbox {Si}$$ Si/Si 0.4 Ge 0.6 / Si quantum well

“…of Si and Si 0.4 Ge 0.6 at room temperature (i.e. at 300 K) are taken from recently published reports [40][41][42][43] for the numerical calculations presented in this paper. The quantum size effects become important when the thickness of the confining layer becomes comparable with the de Broglie wavelength of the electrons and holes.…”

Thermal leakage characteristics of Pt∕SrTiO3∕Pt structures

“…1 Although the electrical properties and the fabrication of devices using Si 1-x Ge x have been thoroughly studied, only limited research has been carried out on their surface chemical cleaning. [3][4][5][6][7][8] Wilde et al reported the existence of hydrogen on HF cleaned Si 1-x Ge x surfaces, 9 but the nature of the surface after HF cleaning is still not clearly understood. In this study, we use synchrotron radiation photoelectron spectroscopy to examine Si 0.85 Ge 0.15 surfaces cleaned by HCl and HF solutions.…”