The electrical conduction across a two-dimensional photonic crystal (PhC) fabricated by Ar/Cl-2 chemically assisted ion beam etching in n-doped InP is influenced by the surface potential of the hol ...

Carrier transport through a dry-etched InP-based two-dimensional photonic crystal

A nitrogen ion beam was used to etch the surface of CuInSe2 single crystals. This technique, applied to CuInSe2 for the first time, was studied with respect to surface damage production at various ion energies and was compared to commonly used argon ion sputtering. Raman scattering and atomic force microscopy were applied as characterization methods. We observed a stress induced redshift of the Raman mode for the argon etched samples which could be explained by tensile stress in the damaged layer. Nitrogen ion beam etching at an energy of 1000 eV causes a blue shift due to the increased lattice damage. Nitrogen ion beam etching at energies below 500 eV was found to produce the lowest degree of damage and the lowest surface roughness, as compared with mechanical polish or argon ion sputtering. Therefore, this method is suitable for dry etching and smoothing of CuInSe2.

Low energy ion beam etching of CuInSe2 surfaces

The reactive ion beam etching (RIBE) of InSb and InAs using -Ar mixtures was investigated as a function of the gas mixture, ion beam energy, ion beam current density and etching time. It has been shown that with increasing :Ar ratio the morphology of the etched surfaces becomes very smooth. For an ion beam energy of 500 eV the surface roughness (root mean square) of InSb was reduced by more than 2 orders of magnitude because of the utilization of instead of Ar at moderate etching rates. Furthermore, in contrast to pure Ar sputtering, no increasing surface roughness with increasing etching time was observed for the RIBE process.

https://iopscience.iop.org/article/10.1088/0268-1242/13/5/014/pdf

Reactive ion beam etching of InSb and InAs with ultrasmooth surfaces

Plasma-induced surface damage of a III–V compound semiconductor, a problem associated with many device fabrication processes, is clarified with careful measurements of surface defect density induced by low energy ion bombardment of InP. In the study, n- and p-InP (110) surfaces were prepared by cleavage of InP in ultrahigh vacuum, and then bombarded as a function of ion type (He+ and Ar+), energy (5–100 eV), and fluence (1012–1017 ions/cm2). The dynamic process of surface Fermi level shifting induced by such bombardment was determined by in situ high-resolution x-ray photoelectron spectroscopy, and the data were then converted to information on surface defect formation. It was found that both He+ and Ar+ bombardment with the above conditions moved the Fermi levels of both n- and p-InP (110) surfaces towards 0.95 eV above the valence band maximum of InP. As expected, for the same bombardment energy, Ar+ caused more damage than He+, and for the same ion type, the bombardment induced a surface defect density...

Damage of InP (110) induced by low energy Ar+ and He+ bombardment

A parametric study of the etch characteristics of Ga-based (GaAs, GaSb, and AlGaAs) and In-based (InGaP, InP, InAs, and InGaAsP) compound semiconductors in BCl3/Ar planar inductively coupled plasmas (ICPs) was performed. The Ga-based materials etched at significantly higher rates, as expected from the higher volatilities of the As, Ga, and Al trichloride, etch products relative to InCl3. The ratio of BCl3 to Ar proved critical in determining the anisotropy of the etching for GaAs and AlGaAs, through its effect on sidewall passivation. The etched features in In-based materials tended to have sloped sidewalls and much rougher surfaces than for GaAs and AlGaAs. The etched surfaces of both AlGaAs and GaAs have comparable root-mean-square (RMS) roughness and similar stoichiometry to their unetched control samples, while the surfaces of In-based materials are degraded by the etching. The practical effect of the Ar addition is found to be the ability to operate the ICP source over a broader range of pressures and to still maintain acceptable etch rates.

Etching of As- and P-based III V semiconductors in a planar inductively coupled BCl3/Ar plasma

Sn-doped InP wafers were etched by reactive ion beam etching (RIBE) using a gas mixture of at ion energies varying from 100 to 600 eV We investigated the radiation damage caused by RIBE using various techniques which are sensitive to the near-surface region The optical and electrical properties of the damaged layer as a function of ion energy were studied by photoluminescence microscopy (PLM), photoluminescence spectroscopy, spectroscopic ellipsometry (SE) and electrochemical capacitance - voltage profiling The electron channelling pattern technique (ECP) was used to examine the structural disorder The observed radiation damage was attributed to the formation of phosphorus vacancies indicating preferential loss of phosphorus in the InP We found optimum etching conditions at an ion energy of 400 eV representing the best trade-off between high etch rate and low radiation damage The potential of PLM, SE and ECP as fast and non-destructive techniques for quality control in research as well as manufacturing is demonstrated

https://iopscience.iop.org/article/10.1088/0268-1242/12/6/019/pdf

Characterization of surface damage in dry-etched InP

In this paper ion-beam-milling of GaAs, InP as well as of InGaAs and InGaAsP of different compositions lattice-matched to InP was investigated using nitrogen and nitrogen/oxygen mixtures. The influence of process parameters such as gas composition, kinetic energy of the ions and the angle of incidence of the ions was investigated in detail. The etch rates of different masking materials like titanium, photoresist and SiO2 are also given. Special attention was paid to the geometry and roughness of the mesa facets in view of their use as laser facets. For the first time the experimental results are compared to calculations based on the sputter theory of Sigmund. The calculated dependence of the etch rates on the kinetic energy of the ions and on the angle of incidence up to 40° is in good agreement with the experimental results.

Ion-Beam-Milling of InGaAsP Alloys with N2/O2-Mixtures

In this paper laser facets are produced by ion beam etching (IBE) for the first time using mixtures of nitrogen and oxygen. The effects of different imperfections of etched facets on the optical reflectivity are investigated. Broad area lasers with both facets cleaved and lasers with one etched and one cleaved facet are fabricated emitting at a wavelength λ=1.55 µ m. The reflectivity of the etched facet is extracted from threshold current measurements. With known reflectivity, the increase of threshold current can be calculated for different resonator dimensions. Although the geometrical requirements for good quality etched laser facets are fulfilled, the reflectivity is still somewhat lower than for cleaved facets. Nevertheless, the expected increase of threshold current for a typical laser structure is only 1.7 mA per facet. The increase is caused by the formation of an antireflection layer, formed by backsputtering.

Gunther Vollrath

Papers

Characterization of surface damage in dry-etched InP

Ion-Beam-Milling of InGaAsP Alloys with N2/O2-Mixtures

Ion-Beam-Etched Laser Facets for InP-based Lasers