Optimized cleaning method for producing device quality InP(100) surfaces

Chemically cleaned GaP͑001͒ surfaces in aqueous HF solutions have been studied using spectroscopic ellipsometry ͑SE͒, ex situ atomic force microscopy ͑AFM͒, x-ray photoelectron spectroscopy ͑XPS͒, wettability, and photoluminescence ͑PL͒ measurements. The SE data clearly indicate that the solutions cause removal of the native oxide film immediately upon immersing the sample ͑Յ1 min͒. The SE data, however, suggest that the native oxide film cannot be completely etch-removed. This is due to the fact that as soon as the etched sample is exposed to air, the oxide starts to regrow. The SE estimated roughness is ϳ1 nm, while the AFM roughness value is ϳ0.3 nm. The XPS spectra confirm the removal of the native oxide and also the presence of regrown oxide on the HF-etched GaP surface. The wettability measurements indicate that the HF-cleaned surface is hydrophobic, which is in direct contrast to those obtained from alkaline-cleaned surfaces ͑hydrophilic͒. A slight increase in the PL intensity is also observed after etching in aqueous HF solutions.

Section: Introductionmentioning

confidence: 99%

Properties of GaP(001) surfaces treated in aqueous HF solutions

Morota

Adachi

2007

“…[1][2][3] Among them, chemical cleaning is the simplest and easiest to control and has been widely applied to GaAs, 2,4-11 InP, 3,10,[12][13][14] GaSb, 15 InAs, 16 InSb, 17 GaN, [18][19][20] and AlN. 19,20 The chemicals used in these studies are mainly acidic solutions ͑HCl, HF, H 2 SO 4 /H 2 O 2 , etc.͒.…”

Section: Introductionmentioning

confidence: 99%

Properties of GaP(001) surfaces chemically treated in NH4OH solution

Morota

Adachi

2006

Chemically cleaned GaP͑001͒ surfaces in 25% NH 4 OH solution have been studied using spectroscopic ellipsometry ͑SE͒, ex situ atomic force microscopy ͑AFM͒, x-ray photoelectron spectroscopy ͑XPS͒, and wettability measurement techniques. The SE data clearly indicate that the solution causes removal of the native oxide film immediately upon immersing the sample. The SE data also indicate that when the native oxide film is completely etch removed, the resulting surface is still roughened. The estimated roughness thickness is ϳ1.2 nm, in excellent agreement with the AFM rms value ͑ϳ1.2 nm͒. The XPS spectra confirm the removal of the native oxide from the GaP surface. The XPS data also suggest a thin oxide overlayer, ϳ0.3 nm thick, on the etch-cleaned GaP surface. The wettability measurements indicate that the as-degreased surface is hydrophobic, while the NH 4 OH-cleaned surface is hydrophilic. This result is in direct contrast to those obtained from acid cleaned surfaces, which are usually hydrophobic. The origin of hydrophilicity may be singular and associated hydroxyl groups bonded on the GaP surface.

“…This indicates that most of the oxidation occurs on the In, while most In-P back bonds are intact. This is because the clean InP starting surface prepared in our study is In terminated [18] and the oxidation occurs at room temperature; there is not enough energy to break the In-P back bonds and cause the further oxidation of phosphorous in InP substrate.…”

Section: Decay Of Quantum Yield Change Of Cs Oxide and Substrate Oximentioning

confidence: 99%

“…Chemical cleaning process described in our earlier work [18] The photoemission spectra are collected at normal emission angle with a PHI (model 10-360) spherical energy analyzer with a multi-channel detector. The spectra are fitted with Voigt functions, which are Gaussian broadened Lorentzian line shapes.…”

mentioning

confidence: 99%

Formation of cesium peroxide and cesium superoxide on InP photocathode activated by cesium and oxygen

Sun

Liu

Pianetta

et al. 2007

Self Cite

Abstract:Activation of p type III-V semiconductors with Cesium and Oxygen has been widely used to prepare Negative Electron Affinity (NEA) photocathodes. However, the nature of the chemical species on the surface after the activation is not well-understood.In this study, InP NEA photocathodes activated with Cesium and Oxygen are studied using Synchrotron Radiation Photoelectron Spectroscopy, also called photoemission.