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Role of Arsenic During Aluminum Droplet Etching of Nanoholes in AlGaAs

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ABSTRACT

Self-assembled nanoholes are drilled into (001) AlGaAs surfaces during molecular beam epitaxy (MBE) using local droplet etching (LDE) with Al droplets. It is known that this process requires a small amount of background arsenic for droplet material removal. The present work demonstrates that the As background can be supplied by both a small As flux to the surface as well as by the topmost As layer in an As-terminated surface reconstruction acting as a reservoir. We study the temperature-dependent evaporation of the As topmost layer with in situ electron diffraction and determine an activation energy of 2.49 eV. After thermal removal of the As topmost layer droplet etching is studied under well-defined As supply. We observe with decreasing As flux four regimes: planar growth, uniform nanoholes, non-uniform holes, and droplet conservation. The influence of the As supply is discussed quantitatively on the basis of a kinetic rate model.

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AFM images of AlGaAs surfaces after LDE with pre-growth overheating, etching at T=605 °C, and varied PAs. a) PAs=7.9×10−7 Torr. b) PAs=2.5×10−7 Torr. c) PAs=1.3×10−7 Torr. d) PAs=6.1×10−8 Torr. The inset in c shows a magnification of the bimodal depth distribution with shallow (sh) and deep (dh) holes
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Fig5: AFM images of AlGaAs surfaces after LDE with pre-growth overheating, etching at T=605 °C, and varied PAs. a) PAs=7.9×10−7 Torr. b) PAs=2.5×10−7 Torr. c) PAs=1.3×10−7 Torr. d) PAs=6.1×10−8 Torr. The inset in c shows a magnification of the bimodal depth distribution with shallow (sh) and deep (dh) holes

Mentions: In the following, we study droplet etching processes with pre-growth overheating (120 s at T=670 °C) for a complete emptying of the As reservoir and, thus, an As supply controlled only by the As flux. Figure 5 shows examples of AlGaAs surfaces after LDE with T=605 °C, FAl=0.4 ML/s, θAl=1.4 ML, and varied PAs controlled by the valve of the As cell. The experiments indicate four As pressure-dependent regimes:


Role of Arsenic During Aluminum Droplet Etching of Nanoholes in AlGaAs
AFM images of AlGaAs surfaces after LDE with pre-growth overheating, etching at T=605 °C, and varied PAs. a) PAs=7.9×10−7 Torr. b) PAs=2.5×10−7 Torr. c) PAs=1.3×10−7 Torr. d) PAs=6.1×10−8 Torr. The inset in c shows a magnification of the bimodal depth distribution with shallow (sh) and deep (dh) holes
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC5037105&req=5

Fig5: AFM images of AlGaAs surfaces after LDE with pre-growth overheating, etching at T=605 °C, and varied PAs. a) PAs=7.9×10−7 Torr. b) PAs=2.5×10−7 Torr. c) PAs=1.3×10−7 Torr. d) PAs=6.1×10−8 Torr. The inset in c shows a magnification of the bimodal depth distribution with shallow (sh) and deep (dh) holes
Mentions: In the following, we study droplet etching processes with pre-growth overheating (120 s at T=670 °C) for a complete emptying of the As reservoir and, thus, an As supply controlled only by the As flux. Figure 5 shows examples of AlGaAs surfaces after LDE with T=605 °C, FAl=0.4 ML/s, θAl=1.4 ML, and varied PAs controlled by the valve of the As cell. The experiments indicate four As pressure-dependent regimes:

View Article: PubMed Central - PubMed

ABSTRACT

Self-assembled nanoholes are drilled into (001) AlGaAs surfaces during molecular beam epitaxy (MBE) using local droplet etching (LDE) with Al droplets. It is known that this process requires a small amount of background arsenic for droplet material removal. The present work demonstrates that the As background can be supplied by both a small As flux to the surface as well as by the topmost As layer in an As-terminated surface reconstruction acting as a reservoir. We study the temperature-dependent evaporation of the As topmost layer with in situ electron diffraction and determine an activation energy of 2.49 eV. After thermal removal of the As topmost layer droplet etching is studied under well-defined As supply. We observe with decreasing As flux four regimes: planar growth, uniform nanoholes, non-uniform holes, and droplet conservation. The influence of the As supply is discussed quantitatively on the basis of a kinetic rate model.

No MeSH data available.


Related in: MedlinePlus