Effects of electron cyclotron resonance etching on the ambient (100) GaAs surface (original) (raw)
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Applied Physics Letters, 1998
Photoreflectance has been used to study the electronic properties of (100) GaAs surfaces exposed to a Cl2/Ar plasma generated by an electron cyclotron resonance source and subsequently passivated by P2S5. The plasma etch shifts the Fermi level of p-GaAs from near the valence band to midgap, but has no effect on n-GaAs. For ion energies below 250 eV, post-etch P2S5 chemical passivation removes the surface etch damage and restores the electronic properties to pre-etch conditions. Above 250 eV, the etch produces subsurface defects which cannot be chemically passivated. Auger electron spectroscopy shows that etching increases As at the GaAs/oxide interface, while passivation reduces it.
Etching of GaAs(100) with Aqueous Ammonia Solution: A Synchrotron-Photoemission Spectroscopy Study
The Journal of Physical Chemistry C, 2010
Etching of the GaAs(100) surface with aqueous ammonia solution is studied by highly surface-sensitive synchrotron-radiation photoemission spectroscopy. It is shown that such treatment effectively removes the native oxide layer leaving the surface covered with elemental arsenic, as well as arsenic hydroxides AsOH and As(OH) 3 , gallium hydroxide GaOH, and gallium suboxide Ga x O. After annealing of the surface at 500°C
The Journal of Physical Chemistry C, 2008
The interaction of the oxide-free GaAs(100) surface with acidic (HCl + 2-propanol) and basic (aqueous NH 3 ) solutions is studied by synchrotron-photoemission spectroscopy. It is found that both solutions attack mostly surface gallium atoms and form weakly soluble gallium chlorides and soluble gallium hydroxides, respectively. Thereby, Ga-As bonds at the surface are broken, and elemental arsenic is left behind on the GaAs surface. In addition, adsorbed 2-propanol molecules are observed on etching with HCl + 2-propanol solution, but no adsorbed water molecules are detected on etching with aqueous ammonia solution.
High-rate electron cyclotron resonance etching of GaAs via holes
Materials Science and Engineering: B, 2000
We report a high-rate etching of GaAs via holes using Cl 2 /Ar plasma generated by an electron cyclotron resonance system. Ni, with a thickness of 200 nm, was used as the etch mask. The effects of the chuck temperature, process pressure, r.f. power, gas flow rate, and microwave power on the etch rate and the resultant etch profiles were investigated. The GaAs etch rate was found to increase as the process pressure, Cl 2 flow rate, and the r.f. power or the microwave power increased. An etch rate as high as 6.7 mm min − 1 was observed from a sample etched using a microwave power, r.f. power and process pressure of 800 W, 150 W and 50 mTorr, respectively. An etch profile, suitable for monolithic microwave integrated circuits via hole applications, has been achieved using the process developed.
Journal of Applied Physics, 1995
The residual damage incurred to GaAs viaetching with a Cl,/Ar plasma generated by an electron cyclotron resonance (ECR) source was investigated as a function of variations in ion energy, ion flux, and etching temperature. The residual damage and electrical properties of GaAs were strongly influenced by changes in these etching parameters. Lattice damage was incurred in all processing situations in the form of small dislocation loops. GaAs etched at high ion energies with 200 W rf power, exhibited a defect density five times higher than GaAs etched at lower ion energies with 20 W rf power. This enhanced residual damage at the higher rf powers was paralleled by a degradation in the unannealed contact resistance. Higher etch rates, which accompany the higher rf power levels, caused the width of the disordered region to contract as the r-f power was elevated. Therefore, the residual etch damage is influenced by both the generationand removal of defects. Increasing the microwave power or ion flux resulted in elevating the residual defect density, surface roughness, and unannealed contact resistance. GaAs etched at high temperatures,-350 "C, resulted in a lower contact resistance than GaAs etched at 25 "C. The high temperature etching augmented the defect diffusion which in turn lowered the near surface defect density. This decrease in residual damage was deemed responsible for improving the electrical performance at 350 "C. The electrical measurements were found to be more sensitive to the density of defects than the vertical extent of disorder beneath the etched surface. Results of this investigation demonstrate that in order to minimize material damage and improve electrical performance, etching with an ECR source should be performed at low rf and microwave powers with a high substrate temperature. 0 I995 American Institute of Physics.
Reconstruction dependence of the etching and passivation of the GaAs(001) surface
JETP Letters, 2010
The methods of the layer by layer or "digital" etching of crystals, which makes it possible to control lably remove monolayers of a crystal and to maintain the atomic smoothness of the surface, have been actively developed in the last two decades. The cre ation of heterostructures for nanoelectronic investiga tions requires not only the layer by layer growth but also layer by layer etching of semiconductors. The dry (gas phase) etching methods such as reactive ion and ion beam etchings, which are widely used in the tech nology of the production of semiconducting struc tures, do not provide the control of etching at the atomic level. The layer by layer etching of III-V semiconducting compounds can be implemented by using adsorbates selectively reacting with atoms of group III or V.
Plasma etching of III–V semiconductors in CH4/H2/Ar electron cyclotron resonance discharges
Journal of Vacuum Science & Technology B: Microelectronics Processing and Phenomena, 1990
We have investigated the etch rates, residual lattice damage, surface morphologies, and chemistries of InP, InGaAs, AlInAs, and GaAs plasma etched in electron cyclotron resonance (ECR) CH4/H2/Ar discharges. The etch rates of InP and InGaAs increase linearly with additional rf biasing of the substrate, and are approximately a factor of 2 faster than for GaAs. Under our conditions the etch rate of Al0.52Ga0.48As is very low (∼25 Å min−1) even for the addition of 100 V rf bias. In all of these materials the residual damage layer remaining after dry etching is very shallow (∼20 Å) as evidenced from Schottky barrier height and photoluminescence measurements combined with wet chemical etching. InP shows significant P depletion with the addition of rf biasing during the ECR etching while GaAs retains a near-stoichiometric surface. Hydrogen passivation of shallow donors in n-type GaAs occurs to a depth of ∼3000 Å during exposure to the CH4/H2/Ar discharge for long periods (60 min). The surf...
Applied Surface Science, 2004
Synchrotron-induced photoelectron spectroscopy was used to investigate the native-oxide-covered GaAs(1 0 0) surface and changes induced by etching with aqueous ammonia solution and by annealing in vacuum. The etching step removes arsenic and gallium oxides from the surface and the surface gets covered by elemental arsenic and tiny amounts of gallium suboxide. The surface oxygen content is reduced by an order of magnitude after etching, whereas the surface carbon content is somewhat increased. Annealing of this surface at 450 8C results in the disappearance of elemental arsenic and a considerable decrease in surface carbon and oxygen contents. The valence band spectra exhibit clear features typical for As-terminated GaAs(1 0 0) surfaces, as also obtained after As decapping. #
Photoreflectance Characterization of Etch-Induced Damage in Dry Etched GaAs
MRS Proceedings, 1993
Photoreflectance has been used to characterize the etch-induced damage in GaAs processed in an Ar/Cl2 plasma generated by an electron-cyclotron resonance (ECR) source. We show that the damage is localized to the surface and that it is most influenced by the RF power, with little effect from the microwave power. The Fermi-level is observed to be unchanged in n-GaAs and remains near midgap, while for p-GaAs, the Fermi level shifts from near the valence band to midgap. Etch-induced anisite defects are proposed as a possible source of the damage.