Selective Area Growth Of GaAs Research Articles

Selective Area Growth of GaAs Nanowires and Microplatelet Arrays on Silicon by Hydride Vapor-Phase Epitaxy

In this work, we demonstrate the growth of vertically oriented GaAs nanowires (NWs) and microplatelets directly on a patterned SiO2/Si(111) substrate by hydride vapor-phase epitaxy (HVPE). Direct condensation of GaAs on Si was achieved through a critical surface preparation under an As-controlled atmosphere. GaAs NWs were grown along the ⟨111⟩B direction with a hexagonal cross section when the hole opening diameter (D) in the SiO2 mask was below 350 nm. Larger apertures (D ≥ 500 nm) resulted in uniform microplatelets. This study highlights the capability of HVPE for selective area growth of GaAs directly on Si and thus the potential of HVPE as a generic heterointegration process for III–V semiconductors on silicon.

Selective Area Growth of GaAs on GaAS (100) by PSE/MBE

Selective Area Growth of GaAs on GaAS (100) by PSE/MBE

GaAs-InGaAs-GaAs Fin-Array Tunnel Diodes on (001) Si Substrates With Room-Temperature Peak-to-Valley Current Ratio of 5.4

In this letter, we report the selective area growth of GaAs, In0.2Ga0.8As, and GaAs/In0.2Ga0.8As/GaAs quantum-well fins of 65-nm width on exactly orientated (001) Si substrates. By exploiting high aspect ratio trenches formed by patterned SiO2 on Si and a V-grooved Si (111) surface in the aspect ratio trapping process, we are able to achieve good material quality and structural properties, as evidenced by x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The fabricated GaAs-In0.2Ga0.8As-GaAs fin-array tunnel diodes exhibit a maximum room-temperature peak-to-valley current ratio of 5.4, and negative differential resistance characteristics up to 200 °C.

Evaluation of growth mode and optimization of growth parameters for GaAs epitaxy in V-shaped trenches on Si

We report the selective area growth of GaAs in V-shaped trenches on Si (001) substrates via metal-organic chemical vapor deposition (MOCVD). High quality GaAs thin films were achieved using a two-step growth process and the aspect ratio trapping method. The evolution of GaAs growth in V-shaped trenches was investigated at all its stages, nucleation layer growth, crystallization, and top layer growth, with the help of in situ normal incidence reflectance measurements. A schematic growth mode was proposed and verified by scanning electron microscope (SEM). We also investigated the impact of nucleation layer thickness and reactor pressure on the crystal quality of GaAs selectively grown on Si through high resolution X-ray diffraction (HRXRD) measurements.

Selective Area Growth of GaAs in V-Grooved Trenches on Si(001) Substrates by Aspect-Ratio Trapping

A high quality of GaAs crystal growth in nanoscale V-shape trenches on Si(001) substrates is achieved by using the aspect-ratio trapping method. GaAs thin films are deposited via metal-organic chemical vapor deposition by using a two-step growth process. Threading dislocations arising from lattice mismatch are trapped by laterally confining sidewalls, and antiphase domains boundaries are completely restricted by V-groove trenches with Si {111} facets. Material quality is confirmed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution X-ray diffraction. Low temperature photoluminescence (PL) measurement is used to analyze the thermal strain relaxation in GaAs layers. This approach shows great promise for the realization of high mobility devices or optoelectronic integrated circuits on Si substrates.

Selective-area growth of GaAs and GaAs/InxGa1-xAs/GaAs nanowires by MOCVD

We have investigated the catalyst-free selective-area growth of GaAs and GaAs/InxGa1-xAs/GaAs (0x3. GaAs nanowire length would become longer by reducing the mask opening size. Thus we can form the GaAs nanowire uniform arrays with appropriate length and width by controling growth conditions and mask opening size. Then the photoluminescence measurement of GaAs/InxGa1-xAs/GaAs (0x<1) core-shell nanowires is carried out.

Selective area metalorganic vapor-phase epitaxy of gallium arsenide on silicon

The selective area, metalorganic vapor-phase epitaxy of gallium arsenide on silicon substrates was investigated. Low-temperature arsenic passivation of the silicon surface was realized at 650 °C. A two-step growth method was used to deposit the GaAs films with an optimum nucleation temperature of 400 °C. Layers nucleated at 350 °C or below were found to be polycrystalline whereas those nucleated at 400 °C and above were single crystal. The X-ray diffraction full-width-at-half-maximum decreased from 890 to 775 arcsec for a 1.0-μm-thick GaAs layer grown on unpatterned versus patterned Si (1 0 0) wafers. The 77 K photoluminescence peak position was 1.489 and 1.498 eV for a 1.0-μm-thick GaAs layer on unpatterned and patterned substrates, respectively. Based on the photoluminescence peak shift, we find that selective area growth of GaAs on Si improves film crystallinity while reducing the in plane strain in the film by 35%.

A detailed comparison of the degree of selectivity, morphology and growth mechanisms between PSE/MBE and conventional MBE

In this paper we compare the degree of selectivity, morphology and growth mechanisms of selective area growth (SAG) performed by periodic supply molecular beam epitaxy (PSE/MBE) and by conventional MBE. In particular we focus on the SAG of GaAs on GaAs(0 0 1) and GaAs(1 1 1)B substrates patterned with a SiO 2 mask. We have observed that the degree of selectivity is considerably higher by PSE/MBE than by conventional MBE when comparing either the samples grown under the same growth conditions or grown under the same effective growth rate. The latter observation confirms that the effectiveness of the PSE technique relies on the enhancement of the decomposition, which occurs during the interruption period, of the polycrystalline islands formed on the mask. Atomic force microscope (AFM) observations proved that the PSE technique does not damage the morphology of the GaAs epilayers. Atomically smooth GaAs epilayers have been grown under completely selective conditions both on GaAs (0 0 1) and GaAs (1 1 1)B substrates. Besides, we have discussed the mechanisms of PSE/MBE and we have evaluated the relevance of the migration and the re-evaporation of the Ga adatoms.

Selective Area Growth by Periodic Supply Molecular Beam Epitaxy

Selective area growth (SAG) was studied by applying periodic supply epitaxy (PSE) to molecular beam epitaxy (MBE). Different growth conditions and PSE parameters were employed, and their influence on the degree of selectivity will be described in detail, The experimental results of the SAG of GaAs and AlGaAs on GaAs (001) and (111)B substrates patterned with a SiO 2 mask will be showed and discussed, The SAG of AlGaAs was found to be very difficult because AlGaAs polycrystalline islands that are formed on the mask require more energy to be decomposed due to the stronger Al–As bonds, Despite the difficulties in SAG by MBE, the PSE technique made it possible to grow selectively smooth epitaxial layers of GaAs and AlGaAs on both kinds of substrates.

Selective-area GaAs growth using nitrogen passivation and scanning-tunneling-microscopy modification on a nanometer scale

A technique for the selective-area growth of GaAs on a nanometer scale is described. The technique comprises nitrogen (N)-passivation mask formation, scanning-tunneling-microscopy (STM) pattern modification, and metalorganic molecular-beam epitaxy. GaAs (001) surfaces are passivated with N radicals dissociated from N2 molecules and are modified by STM on a nanometer scale. GaAs nanostructures are then grown on the modified areas using trimethylgallium and tertiarybutylarsine. Uniform 6-nm-high and 50×50-nm2 dots were formed on 50×50-nm2 STM-modified areas. The advantage of the technique is that size-controlled nanostructures can be fabricated in specific positions and these nanostructures are free from contamination because all processes are performed in a vacuum.

Growth, doping, and etching of GaAs and InGaAs using tris-dimethylaminoarsenic

Growth, doping, and in situ etching of GaAs using cracked and uncracked tris-dimethylaminoarsenic (TDMAAs) in chemical beam epitaxy (CBE) have been studied. A reflection high-energy electron diffraction study indicates that the complete decomposition of TDMAAs occurs below 370 °C. Possible TDMAAs decomposition pathways, which are consistent with experimental data, are presented. The carbon level in undoped GaAs films and the hole concentration in carbon-doped GaAs films using uncracked TDMAAs are much lower than those using cracked TDMAAs, which may be due to atomic hydrogen released from the β-hydride elimination process of uncracked TDMAAs on the GaAs surface. The in situ GaAs etching effect was observed only when the substrate was exposed to uncracked TDMAAs. Possibly, reactive free radicals generated by uncracked TDMAAs on GaAs surfaces are responsible for the etching effect. Surface roughness in selective-area growth of GaAs and the poor interfaces in InGaAs/GaAs multiple quantum wells grown by CBE using uncracked TDMAAs may result from this etching effect.

Selective area chemical beam epitaxy of GaAs using Ga 2O 3 as a mask layer

We have demonstrated selective area growth of GaAs by chemical beam epitaxy using Ga 2O 3 mask layers deposited by RF sputtering. The temperature window for selective area growth has been defined by both pre-annealing and growth temperatures, being primarily limited by the sublimation of Ga 2O 3.

In situ selective area growth of GaAs, AlAs, and AlGaAs using MOMBE

We investigated source-gas combinations for realizing the in situ selective area growth (SAG) of GaAs, AlAs, and AlGaAs using an atomically thin GaN mask. Trimethylgallium (TMG), dimethylaluminumhydride (DMAH), dimethylethylaminealane (DMEAA), trisdimethylaminoarsine (TDMAAs), and As 4 were examined as source materials. As a result, GaAs SAG was realized using (TMG, As 4) and (TMG, TDMAAs), and AlAs SAG was also performed using (DMAH, TDMAAs). As for GaAs and AlAs SAG, TDMAAs is effective for reducing the carbon contamination. Furthermore, AlGaAs SAG was realized by using TMG, DMAH, and TDMAAs.

Increasing the range of growth temperatures available for GaAs selective area growth using triisopropylgallium and arsine

This paper reports the first assessment of triisopropylgallium (TIPGa) for the selective area growth of GaAs using chemical beam epitaxy. Modulated beam mass spectrometry has been used to study the decomposition of TIPGa on oxides of silicon and GaAs, with both pre-cracked arsine and tris(dimethylamino)arsenic (TDMAAs) as the group V source. Experiments have been performed as a systematic function of growth temperature, both with and without the group V flux, and a comparison made with the use of triethylgallium (TEGa) in place of TIPGa. Using pre-cracked arsine as the group V source, we have demonstrated that TIPGa does not decompose on a silicon oxide surface for all growth temperatures above 450°C, whereas temperatures over 560°C are required to achieve total selectivity when using TEGa as the group III source. Studies using TIPGa and TDMAAs also demonstrate selectivity across a wide temperature range.

Periodic supply epitaxy: a new approach for the selective area growth of GaAs by molecular beam epitaxy

Selective growth of GaAs on a GaAs substrate with a SiO 2 patterned mask has been carried out by molecular beam epitaxy at 630°C, using molecular beams of Ga and As 4 as sources and employing a periodic supply epitaxy technique for the first time. The GaAs crystalline nuclei deposited on the mask surface are decomposed and the atoms adsorbed on the mask surface are evaporated or allowed to migrate until they are captured by the single crystalline epitaxial layer. A wide depleted zone is then formed and the polycrystals of GaAs are located beyond this area. The surface migration is shown to influence drastically the thickness of the grown layer. The epitaxial layer obtained is flat and smooth even for the (001) substrates, since the lateral flux prevents the decomposition of GaAs on the free surface of the epitaxial layer. The growth technique is discussed in details, together with an analysis of the important parameters for the selective growth by periodic supply epitaxy.

Selective area growth of GaAs using a Ga beam with a step-function lateral intensity profile

Selective area growth of GaAs has been carried out in order to investigate the surface diffusion of Ga atoms using molecular beam epitaxy (MBE) with the aid of a Ga beam with a lateral step-function intensity profile. This step-function profile was obtained using a closely fitted GaAs shadow mask. When the mask edge was parallel to [01 1 ], a (311)A facet was typically observed near the edge of the Ga beam, while in the case of the mask edge parallel to [011], a (111)B facet was formed. MBE growth simulation based on the diffusion model was carried out in order to understand the mechanism of this selective area growth. The calculated results were in good agreement with the experimental results, and the diffusion lengths of Ga atoms were determined to be 0.10 μm along [011] direction on the (100) GaAs surface, 0.37 μm along [233] direction on the (311)A GaAs surface and 0.17 μm along [21 1 ] direction on the (111)B GaAs surface during MBE growth. These diffusion lengths seem to be smaller than those previously observed, which is probably due to a large V III ratio in the region of the substrate close to the mask edge.

Selective area growth of GaAs using a Ga beam with a step-function lateral intensity profile

Selective area growth of GaAs using a Ga beam with a step-function lateral intensity profile

Uniform selective area growth of GaAs and GaInP by low temperature chemical beam epitaxy

Selective area chemical beam epitaxy (CBE) has been investigated for GaAs and GaInP materials. Three topics are considered in this work: the critical temperature for selective growth, the compositional variation of GaInP on patterned surfaces and the topology of the localized epitaxy. The major results of this study are: (i) the decrease of the growth rate appears to lower drastically the critical selective growth temperature so that GaAs and GaInP can be selectively grown under the optimized temperature conditions defined for CBE, (ii) the composition of the GaInP alloy, analysed by 300 K photoluminescence, is found to be uniform in the selectively grown stripes compared to the unpatterned substrate, (iii) growth conditions have been established to selectively grow GaAs stripes limited by vertical sidewalls.

Selective Area Growth of GaAs by Periodic Supply Epitaxy

Selective Area Growth of GaAs by Periodic Supply Epitaxy

InGaAs/GaAs quantum well lasers with dry-etched mirror passivated by vacuum atomic layer epitaxy

We report measurements of strained InGaAs/GaAs quantum well laser diodes with electron cyclotron resonance (ECR) plasma etched mirrors that are passivated and smoothed with a novel technique involving the selective area growth of GaAs by vacuum atomic layer epitaxy. The threshold current of as-cleaved, etched, and passivated devices has been studied and a significant improvement in mirror feedback is shown with the passivation and smoothing of etched mirrors oriented along the [001] planes.