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Optimization of an inductively coupled plasma etching process of GaInP/GaAs based material for photonic band gap applications
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In this article, we investigate the dry etching of GaInP/GaAs based material system using an inductively coupled plasma (ICP) etching system. In a view to develop a suitable ICP process for the etching of aluminum-free material, ridge waveguides have been fabricated and the effects of the ICP parameters have been assessed. The coil power and the platen power have been varied at constant pressure and temperature for a chlorine-based process. The surface quality, sidewall profile, and selectivity have been reported. We also demonstrate the optimization of the chlorine-based process for deep etching and its subsequent implementation in photonic band gap device fabrication for 1.55 μm optical applications. The optimized process has been shown to provide a high aspect ratio and a good selectivity for 250 nm diam holes with a depth of 3 μm in the GaInP/GaAs material system. The influence of the ICP parameters on this material system have been analyzed mainly by scanning electron microscopy with particular attention drawn to the ways of reducing trenching, an effect commonly associated with ICP etching.
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... Etching of InGaP can have some difficulties because of the higher average bond energy (compared to AlGaAs) and the formation of low volatile reaction products InCl z when using a chlorine-based etch chemistry [53,54]. For this process elevated temperatures are needed for etching the less volatile InCl z , since nonvolatile surface products can prevent etching. ...
... Analogically to the phenomenon occurring on Si when etched by SF 6 /O 2 plasma. Addition of N 2 also lead to anisotropic etching [4,11]. The mechanism of stable and non porous P 2 N 5 formation is not evidenced today. ...
In the present study, I will propose an alternative for process development in microelectronics. This approach is about to use a multi-scale approach to simulate a pattern transfer of material. This multi-scale approach is an interesting way to reduce the traditional experimental set. The model is able to explain the evolution of the profile observed with different parameter variation as pressure, power source and chlorine partial pressure. It give access to many information as the flux of species and the proportion of ions to the surface. We first make a DOE with this model. This DOE allows to propose a set of optimized input parameters to etch InP by Cl2/Ar plasma. This first set of results shows that the model can help to build and drive an experimental DOE. This last can be focused around the better input parameters. Or, it also can drive the engineer to change the plasma mixture.
... In addition to the mode-gap cavity, high-Q delocalized modes spanning the barrier waveguide occur. The fabrication method is described in detail in Ref. [34]. The PhC is mounted in a nitrogen filled dust-free box to prevent oxidation. ...
We measure the dynamics of the thermo-optical nonlinearity of both a mode-gap nanocavity and a delocalized mode in a Ga$_{\mathrm{0.51}}$In$_{\mathrm{0.49}}$P photonic crystal membrane. We model these results in terms of heat transport and thermo-optical response in the material. By step-modulating the optical input power we push the nonlinear resonance to jump between stable branches of its response curve, causing bistable switching. An overshoot of the intensity followed by a relaxation tail is observed upon bistable switching. In this way, the thermal relaxation of both the localized resonance and the delocalized resonance is measured. Significant difference in decay time is observed and related to the optical mode profile of the resonance. We reproduce the observed transient behavior with our thermo-optical model, implementing a non-instantaneous nonlinearity, and taking into account the optical mode profile of the resonance, as experimentally measured.
... In addition to the mode-gap cavity, high-Q delocalized modes spanning the barrier waveguide occur. The fabrication method is described in detail in Ref. [34]. The PhC is mounted in a nitrogen filled dust-free box to prevent oxidation. ...
We measure the dynamics of the thermo-optical nonlinearity of both a mode-gap nanocavity and a delocalized mode in a Ga0.51In0.49P photonic crystal membrane. We model these results in terms of heat transport and thermo-optical response in the material. By step-modulating the optical input power we push the nonlinear resonance to jump between stable branches of its response curve, causing bistable switching. An overshoot of the intensity followed by a relaxation tail is observed upon bistable switching. In this way, the thermal relaxation of both the localized resonance and the delocalized resonance is measured. Significant difference in decay time is observed and related to the optical mode profile of the resonance. We reproduce the observed transient behavior with our thermo-optical model, implementing a non-instantaneous nonlinearity, and taking into account the optical mode profile of the resonance, as experimentally measured.
... Bromine (Br) solution has been used in the non-selective mesa etching for InGaP/GaAs structures [82]. Use of Inductively Coupled Plasma (ICP) etching was also reported [83]. However in the course of this thesis, fabrications with these techniques were not possible due to time limitations and technical constraints of the ICP equipment. ...
Optomechanics studies the interaction between light and mechanical motion. This PhD thesis reports on optomechanical experiments carried with miniature disk resonators fabricated out of distinct III-V semiconductors: Gallium Arsenide (GaAs), Aluminium Gallium Arsenide (AlGaAs) and Indium Gallium Phosphide (InGaP). These materials are compliant with optoelectronics functionalities and provide giant optomechanical coupling. In order to boost performances of GaAs resonators, we implemented surface control techniques and obtained a ten-fold reduction of optical dissipation, attaining a Q of six million. On top of GaAs, we performed a comparative investigation of optomechanical interactions in InGaP and AlGaAs disk resonators, and demonstrated their operation as optomechanical oscillators. Finally, we carried out optomechanical force sensing experiments with GaAs resonators, analyzing a new sensing principle in light of the phase space trajectory and phase noise of the corresponding oscillators
Integration of devices generating non-classical states (such as entanglement) into photonic circuits is one of the major goals in achieving integrated quantum circuits (IQCs). This is demonstrated successfully in recent decades. Controlling the non-classicality generation in these micron-scale devices is also crucial for the robust operation of the IQCs. Here, we propose a micron-scale quantum entanglement device whose nonlinearity (so the generated non-classicality) can be tuned by several orders of magnitude via an applied voltage without altering the linear response. Quantum emitters (QEs), whose level-spacing can be tuned by voltage, are embedded into the hotspot of a metal nanostructure (MNS). QE-MNS coupling introduces a Fano resonance in the “nonlinear response”. Nonlinearity, already enhanced extremely due to localization, can be controlled by the QEs’ level-spacing. Nonlinearity can either be suppressed or be further enhanced by several orders. Fano resonance takes place in a relatively narrow frequency window so that ∼meV voltage-tunability for QEs becomes sufficient for a continuous turning on/off of the non-classicality. This provides as much as 5 orders of magnitude modulation depths.
Color conversion by (tapered) nanowire arrays fabricated in GaInP with bandgap emission in the red spectral region are investigated with blue and green source light LEDs in perspective. GaInP nano- and microstructures, fabricated using top-down pattern transfer methods, are derived from epitaxial Ga0.51In0.49P/GaAs stacks with pre-determined layer thicknesses. Substrate-free GaInP micro- and nanostructures obtained by selectively etching the GaAs sacrificial layers are then embedded in a transparent film to generate stand-alone color converting films for spectrophotometry and photoluminescence experiments. Finite-difference time-domain simulations and spectrophotometry measurements are used to design and validate the GaInP structures embedded in (stand-alone) transparent films for maximum light absorption and color conversion from blue (450 nm) and green (532 nm) to red (~ 660 nm) light, respectively. It is shown that (embedded) 1 μm-high GaInP nanowire arrays can be designed to absorb ~ 100% of 450 nm and 532 nm wavelength incident light. Room-temperature photoluminescence measurements with 405 nm and 532 nm laser excitation are used for proof-of-principle demonstration of color conversion from the embedded GaInP structures. The (tapered) GaInP nanowire arrays, despite very low fill factors (~ 24%), can out-perform the micro-arrays and bulk-like slabs due to a better in- and out-coupling of source and emitted light, respectively.
In this letter, we introduce for the first time a nano-fin patterning technique that combines Au electro-plating and high-temperature InGaAs dry etching processes. We applied this technique to fabricate vertical homojunction InGaAs tunnel-field-effect-transistors (TFETs). An InGaAs fin width (Wfin) of 60 nm was implemented with excellent line-edge-roughness (LER). The fabricated vertical homojunction InGaAs TFETs with a gate length (Lg) of 100 nm exhibited excellent device characteristics, such as a minimum subthreshold swing (Smin) of 80 mV/decade, an on–off-ratio (ION/IOFF) of 6.09 × 10² at VDS = 0.3 V, and a drain induced barrier lowering (DIBL) of 208 mV/V at room temperature.
All-optical processing is based on fast nonlinear effects, such that light can be used to control light. The development of a novel class of low-loss semiconductor optical resonators, capable of field confinement close to the diffraction limit, has decreased the power level required to trigger nonlinear effects by several orders of magnitude. We review a decade of research on all-optical gates aiming both at fast and energy-efficient operation, with the prospect of integration on a silicon photonics platform.
This study demonstrates etch profile engineering of InP, In 1x Ga x As 1y P y , and In 0.53 Ga 0.47 As heterostructures results from adding H 2 to standard Cl 2 /Ar inductively coupled plasma-reactive ion etching chemistries. Etch rate curves of bulk InP, In 1x Ga x As 1y P y , and In 0.53 Ga 0.47 As show a general parabolic trend as a function of the H 2 component of the Cl 2 /Ar/H 2 ratio. Three distinct etching profiles of InP/InGaAsP layers were realized by varying the Cl 2 /Ar/H 2 ratio. Highly anisotropic profiles result for Cl 2 /Ar/H 2 ratios between 2/3/1 and 2/3/2. Waveguiding structures fabricated using this technology are presented with a loss as low as 2 dB/cm. An InP racetrack resonator with a quality factor (Q)8000 is also presented. © 2002 American Vacuum Society.
We studied dry etching of AlGaAs and InGaP in a planar inductively coupled BCl3 plasma. The process parameters were planar ICP source power (0–500 W), reactive ion etching (RIE) chuck power (0–150 W), and chamber pressure (5–15 mTorr). The process results were characterized in terms of etch rate, surface morphology, and surface roughness. The planar inductively coupled BCl3 plasmas were also monitored with in situ optical emission spectroscopy (OES). BCl3 planar inductively coupled process (ICP) etching of AlGaAs showed very vertical sidewall, clean and smooth surface, while that of InGaP showed somewhat rough surface after etching. Etch rates of AlGaAs were generally higher than those of InGaP in the planar BCl3 ICP etching. It indicated that InClX byproducts had relatively low volatility during InGaP etching in the planar inductively BCl3 plasmas. Increase of ICP source power and RIE chuck power strongly raised etch rates of both AlGaAs and InGaP. That of pressure decreased etch rate of both materials. OES data showed that emission intensity of the planar BCl3 ICP was a strong function of ICP source power and chamber pressure, while it was almost independent of RIE chuck power. © 2003 American Vacuum Society.
Etching of InGaAs and InP in inductively coupled plasma (ICP) using SiCl 4 was studied for heterojunction bipolar transistor (HBT) applications. Low sample temperature was used to minimize etching isotropy and to reduce group V element desorption. The low ion energy etching process results in a damaged layer thickness of a few Å. Auger electron spectroscopy results on InP demonstrate a very thin layer of nonstoichiometric material. The nature of the etching mask impacts the surface contamination: local contamination effects due to sputtering are observed. For such low ion energy process, the sample preparation before ICP etching is shown to be very important for surface roughness, as observed by atomic force microscopy. Various preparation schemes have been investigated, before ICP etching, for reduction of the surface degradation resulting from ICP etching. It is shown that the best results in terms of roughness and etch-rate are obtained with a silicon nitride mask and surface oxidation by ultraviolet ozonization before a wet desoxidation immediately preceding the ICP etching. An ICP process was used successfully for partly etching the base mesa of HBT structures. No significant difference with wet etching was observed in terms of induced damage and HBT current gain.
Two plasma chemistries, i.e., CHâ/Hâ/Ar and Clâ/Ar, were compared for the etching of InGaP, AlInP, and AlGaP under inductively coupled plasma (ICP) conditions. While the etching with CHâ/Hâ/Ar discharges appears to be ion driven, Clâ/Ar discharges showed an additional strong chemical enhancement. The highest etch rate (â¼1 μm/min) for InGaP was achieved at high ICP source power (â¥750 W) with the Clâ/Ar chemistry. Clâ/Ar discharges provided very smooth surfaces in all three materials with root-mean-square roughness measured by atomic force microscopy around 2 nm. This result may be due to the efficient ion-assisted product desorption in this chemistry. The etched near-surface region of InGaP (â¼100 â«) with Clâ/Ar maintained almost the same stoichiometry as that of the unetched control. By contrast, the CHâ/Hâ/Ar plasma chemistry produced somewhat rougher surfaces and depletion of phosphorous (P) from the surface of InGaP. {copyright} {ital 1998 American Vacuum Society.}
The reactive ion etching of the GaInP/GaAs multilayer structure using SiCl4, Cl2 and Ar was examined. Different plasma compositions were tested and a mixture containing principally SiCl4 was chosen. Experiments were performed with power densities between 0.01 and 0.78 W cm−2 and at pressures between 2 and 50 mTorr. Etching mechanisms and the surface morphology are discussed briefly and compared with results for substrate materials processed under the same plasma conditions. Orientation independent etching of 5 μm high posts with no selectivity between GaInP and GaAs is reported. The sidewalls are smooth and contamination free.
Both Ga-based (GaAs, AlGaAs) and In-based (InGaP, InP, InAs, and InGaAsP) compound semiconductors were etched in a planar inductively coupled plasma (ICP) reactor in pure BCl3. The Ga-based materials etched at significantly higher rates, as expected from the higher volatilities of their trichloride etch products relative to InCl3. In contrast to the more common cylindrical geometry ICP sources, the dc self-bias which controls ion energy is not strongly dependent on source power up to ∼400 W while etch rates increase rapidly over this power range. The source tunes easily even at very low powers (<100 W) but operates inefficiently above ∼10 mTorr, with a marked decrease in both emission intensity from the discharge and in resulting etch rates of the compound semiconductors. The etched surfaces of both AlGaAs and GaAs have comparable root-mean-square roughness and similar stoichiometry to the unetched control samples, while the surfaces of In-based materials are degraded by the BCl3 etching.
We report on the application of electrostatic force microscopy to photovoltaic devices. Profiles of electrical potentials on cross sections of a GaInP2 solar cell device were measured quantitatively and spatially resolved. Two potentials are assigned, respectively, to the p–n junction of GaInP2 and the band offset between the GaInP2 base layer and the GaAs substrate. In addition to the flattening of the p–n junction by the light irradiations, two changes of the potential that positively contribute to the open-circuit voltage of the device are found at locations close to the window and the back surface field layers. © 2002 American Institute of Physics.
The conduction‐band discontinuity for GaInP/GaAs metalorganic chemical vapor deposition (MOCVD) HBTs has been determined from current–voltage characterization. The charge‐control model used permits to compare the respective weights of collector current limitations due to the potential barrier effect and to the carrier diffusion mechanism in the low gap base region. A study of sensitivity to the main sources of error leads to a conduction‐band offset value of ΔEC≊170±16 meV confirming the advantage of the resulting band lineup for the HBT. © 1996 American Institute of Physics.
The dry etch selectivity of GaAs over InGaP in BCl3/SF6 discharges with additives of He, Ar, or Xe under Inductively Coupled Plasma conditions was examined. Selectivities over 200 were achieved in BCl3/SF6 or BCl3/SF6/He at low ion energies and moderate ion fluxes. The mechanism for achieving selective etching was studied with Electron Spectroscopy for Chemical Analysis, and is due to formation of non-volatile InClX and InFX reaction products. The key to achieving high selectivity is to minimize sputter-induced desorption of these reaction products. Ion-induced damage in the InGaP was also minimized at low ion energies and moderate ion fluxes.