Tertiarybutylarsine Research Articles

MOCVD growth of 980 nm InGaAs/GaAs/AlGaAs graded index separate confinement heterostructure quantum well lasers with tertiarybutylarsine

InGaAs/GaAs/AlGaAs quantum well (QW) structures have been grown at different temperatures by metalorganic chemical vapor deposition (MOCVD) with tertiarybutylarsine (TBAs) as the group V source, and it is found that the QW structures grown at 640 °C shows the strongest photoluminescence (PL) emission. Based on the optimized growth conditions, the InGaAs/GaAs/AlGaAs graded index (GRIN) separate confinement heterostructure (SCH) double quantum well lasers have been grown with TBAs. The 4-μm-wide ridge waveguide lasers show room temperature continuous-wave lasing around 980 nm, with a typical threshold current of 14 mA, indicating that TBAs could be a promising alternative to the highly hazardous gas source AsH 3 in growing InGaAs/GaAs/AlGaAs 980 nm QW lasers.

Effect of group V partial pressure on the kinetics of selective area MOVPE for GaAs on (1 0 0) exact and misoriented substrate

Surface reaction kinetics of GaAs growth by metalorganic vapor phase epitaxy (MOVPE) was investigated by examining the growth rate non-uniformity of open area in selective area MOVPE. The surface reaction rate constant ( k s) could be extracted using this technique and the effect of tertiarybutylarsine (TBAs) partial pressure ( p TBAs) on k s was examined on GaAs (1 0 0) exact and misoriented substrates in the temperature range 550–700 °C. The activation energy of k s was significantly dependent on the growth temperature range and on p TBAs. This is due to the change of the probable reactant formed by the gas-phase reaction and also due to the GaAs (1 0 0) surface reconstruction which depends on temperature and p TBAs. At 575 and 700 °C, the relation between k s and p TBAs was examined at a constant trimethylgallium (TMGa) partial pressure or V/III ratio, respectively. The desorption of As from the GaAs surface should be taken into account at lower p TBAs. At higher p TBAs, the surface reconstruction state, the potential reaction between As species and As sites on the surface and the organic by-product from TBAs might be responsible for the reduction of k s value.

InGaAsP/GaInP/AlGaInP 0.8 μm QW lasers grown by MOCVD using TBP and TBAs

InGaAsP epilayers and InGaAsP/GaInP single quantum well (SQW) structures have been grown by metalorganic chemical vapor deposition (MOCVD) on GaAs substrates using tertiarybutylphosphine (TBP) and tertiarybutylarsine (TBAs) as group V sources. Both InGaAsP epilayers and InGaAsP/GaInP SQW structure show strong photoluminescence emission, suggesting good optical quality. Finally, ridge waveguide InGaAsP/GaInP/AlGaInP QW lasers have been demonstrated with an emission wavelength around 0.8 μm and a threshold current of 24 mA under continuous wave operation at room temperature, indicating TBP and TBAs are as good as PH 3 and AsH 3 for the growth of high-power 0.8 μm lasers.

Optimisation of pulsed anodic oxidation for the fabrication of AlGaInP laser diodes grown with tertiarybutylarsine and tertiarybutylphosphine

GaInP/AlGaInP triple quantum well (TQW) laser structures were grown by low-pressure metalorganic chemical vapour deposition (MOCVD) with tertiarybutylarsine (TBAs) and tertiarybutylphosphine (TBP). Device fabrication was carried out using the pulsed anodic oxidation (PAO) process, which was optimised for the (Al0.7Ga0.3)0.52In0.48P upper cladding layer of the laser structure using photoluminescence (PL) measurements and atomic force microscopy (AFM) characterisation. AlGaInP laser diodes, grown with TBAs and TBP, fabricated under the optimised oxidation conditions, exhibit the lowest reported threshold current density (Jth) of 1.5 kA/cm2 at room temperature (RT) under pulsed operation.

Chemical beam epitaxy of InGaAsN films for multi-junction tandem solar cells

Chemical beam epitaxy (CBE) offers a new growth technique for InGaAsN films that are expected to provide the third cell in an ultra-efficiency 4-junction tandem III–V solar cell. In the CBE system, the selection of arsenic (As) and nitrogen (N) sources is important, so the decomposition processes of As (TBAs, TDMAAs) and N (DMHy, MMHy) precursors were investigated with substrate temperature. Both tertiarybutylarsine (TBAs) and trisdimethylaminoarsenic (TDMAAs) were decomposed at a low temperature (<300 °C). While methyl alkyl and tertiarybutyl radical were produced by decomposition of TBAs, Dimethylamine and Aziridine were produced during the decomposition of TDMAAs. The residual carbon concentration in GaAs films grown with TDMAAs was less than 10 16 cm −3. The incorporation of N in GaAsN films grown with DMHy and MMHy decreased with increasing substrate temperature, and the incorporation of N in GaAsN films grown with MMHy was higher.

Growth of InGaAsP based asymmetric quantum well infrared photodetector using metalorganic vapor phase epitaxy

A lattice-matched InyGa1−yAszP1−z∕InwGa1−wAsvP1−v∕InxGa1−xAs asymmetric step quantum well infrared photodetector grown by low-pressure metalorganic vapor phase epitaxy (MOVPE) using N2 carrier with tertiarybutylarsine (TBA) and tertiarybutylphosphine (TBP) is reported. The spectral responsivity of the detector has its peak at a wavelength of 10.7 μm with a peak responsivity of 0.19 A/W under 0.8 V bias at 25 K. A maximum peak detectivity of 1.9×109cmHz1∕2∕W was achieved under 0.6 V bias at 25 K. The measured activation energy using thermionic emission of carriers is found to be about 81 meV. This work demonstrates the fabrication of InP based quantum well infrared detectors using MOVPE with TBA and TBP sources with performance comparable to that achieved using molecular beam epitaxy.

Feedback control of surface roughness of GaAs (0 0 1) thin films using kinetic Monte Carlo models

In this work, we follow the methodology presented in Lou and Christofides [Estimation and control of surface roughness in thin-film growth using kinetic Monte-Carlo models, Chem. Eng. Sci. 58 (2003a) 3115–3129] to study estimation and control of surface roughness of gallium arsenide (GaAs) (0 0 1) thin films during deposition in a horizontal-flow quartz reactor using triisobutylgallium (TIBGa) and tertiarybutylarsine (TBAs) as precursors with H2 as the carrier gas. The adsorption of TIBGa onto the surface and the migration of Ga atoms on the surface are considered as the two rate-limiting steps in the film growth and are explicitly modeled within a kinetic Monte Carlo simulation framework. The energy barrier and the pre-exponential factor of the migration rate of Ga atoms on the surface used in the simulations are initially determined by fitting the simulation results to experimental data reported in Law et al. [Analysis of the growth modes for gallium arsenide metalorganic vapor-phase epitaxy, J. Appl. Phys. 88 (2000) 508–512]. Then, a roughness estimator is constructed that allows computing estimates of the surface roughness of the GaAs thin films at a time-scale comparable to the real-time evolution of the process using discrete on-line roughness measurements. The estimator involves a kinetic MC simulator based on multiple small-lattice models, an adaptive filter used to reduce roughness stochastic fluctuations and an error compensator used to reduce the error between the roughness estimates and the roughness measurements. The roughness estimates are fed to a proportional–integral (PI) feedback controller which is used to control the surface roughness to a desired level by manipulating the substrate temperature. Application of the proposed estimator/controller structure to the process model based on a large-lattice kinetic Monte Carlo simulator demonstrates successful regulation of the surface roughness to the desired level. The proposed approach is shown to be superior to PI control with direct use of the discrete roughness measurements. The reason being that the available measurement techniques do not provide measurements at a frequency that is comparable to the time-scale of the dominant film growth dynamics.

Metalorganic chemical vapor deposition and spontaneous emission of self-assembled InAs quantum dots in open space and in a planar microcavity

Metal organic chemical vapor deposition of InAs quantum dots (QDs) and GaAs/AlAs planar microcavities with InAs QDs as active layer using tertiarybutylarsine (TBAs) as arsenic precursor is reported. The effects of crucial growth parameters on growth of the InAs QDs are studied. The spontaneous emission (SE) of InAs QDs in open space and in planar microcavties are investigated using Photoluminescence (PL) and time resolved PL spectra. The behaviors of PL and time resolved PL of InAs QDs in open space can be explained in terms of thermal redistribution of carriers and carrier transfer between quantum dots. The SE rate of InAs QDs can be enhanced in the presence of a microcavity.

MOCVD growth of InGaAsP/InGaAs multi-step-quantum well structure for QWIP application by using TBA and TBP in N 2 ambient

Metalorganic chemical vapor deposition (MOCVD) growth of InGaAsP/InGaAs multiple step quantum well (MSQW) structure for quantum well infrared photodetector (QWIP) applications by using tertiarybutylarsine (TBA) and tertiarybutylphosphine (TBP) in 100% nitrogen (N 2) atmosphere is reported. X-ray diffraction (XRD) measurement shows the high quality of the quantum well structure grown. Fourier transform infrared spectroscopy (FTIR) measurement on the MSQW structure shows an about 11 μm absorption peak and indicates this MSQW structure is useful for realization of QWIP. The measured absorption spectrum agrees with the theoretical calculated results. Both crystal property and optical characterization of the MSQW structure grown show the feasibility of MOCVD growth using TBA and TBP in pure N 2 ambient.

LP-MOVPE growth of InAs quantum dots using tertiarybutylarsine (TBA) in pure N 2 ambient

The InAs quantum dots on GaAs (0 0 1) substrate were first grown by LP-MOVPE using tertiarybutylarsine (TBA) in nitrogen ambient. Samples were characterized using atomic force microscope (AFM) and photoluminescence (PL) spectroscopy at 77 K. The average diameter of the dots increases with the group III source trimethylindium (TMIn) inlet flow. The shape of dots also changes with the TMIn inlet flow. The shape of dots changes from oval to circle, respectively, when the TMIn inlet flow was changed from 60 to 80 sccm. When TMI was set at 100 sccm, the shape of InAs quantum dots is tetrahedron with two {1 4 14} facets and one {1 1 14} facet and their edges were parallel to [1 4 0] and [1 1 0] directions, respectively. The dot density is (1.5–2.5)×10 10 cm −2. The PL emission from the quantum dots is centered at 1071 nm wavelength and has a full width at half maximum PL spectrum of 55 meV.

AlGaAs/GaAs Quantum Well Lasers Grown by Metalorganic Chemical Deposition Using Tertiarybutylarsine in Nitrogen Ambient

Using tertiarybutylarsine (TBAs) as the arsenic precursor and the nitrogen as the carrier gas, high-quality AlGaAs/GaAs quantum well (QW) diode laser materials have been grown by metalorganic chemical vapor deposition (MOCVD). Photoluminescence and device measurement studies indicate that the quality of the grown AlGaAs/GaAs laser materials can be comparable to those grown by using AsH3 as the arsenic precursor and hydrogen as the carrier gas. For the first time, a low threshold current density of 200 A/cm2 for 1000 µm cavity length broad area AlGaAs/GaAs lasers has been achieved by this MOCVD growth method. It has been shown that TBAs and nitrogen gas can be employed in MOCVD growth of the widely used AlGaAs/GaAs laser materials, for substituting the highly toxic source gas AsH3 and the highly explosive carrier gas H2.

Morphology and optical properties of GaAs layers grown on (1 1 1)A GaAs substrates in N2ambient by metalorganic chemical vapor deposition

Using tertiary-butyl arsine as a group V precursor, GaAs epitaxial layers have been grown on both (1 1 1)A- and (1 0 0)-oriented GaAs substrates in N2 ambient using the atmospheric metalorganic chemical deposition technique. The surface morphology and optical properties of the GaAs homoepitaxial layers were studied in detail. It is found that both the surface morphologies and optical properties of GaAs layers on (1 1 1)A GaAs substrates depend much more strongly on the combination of growth temperature and V/III input molar ratio, compared to the epitaxial layers on (1 0 0) plane GaAs. The photoluminescence (PL) emission efficiency increases with increasing growth temperature in the region 550–650 °C for both (1 1 1)A and (1 0 0) GaAs epitaxial layers. At room temperature, the PL emission intensity of the (1 1 1)A GaAs epilayer grown under optimum growth conditions is 67 times as strong as that of the same run-grown (1 0 0) GaAs epilayer.

Strain effects on highly strained InAsP/InGaP multi-quantum well structures grown by MOVPE using TBAs and TBP

The influence of the strain on the material quality of highly strained InAsP/InGaP multi-quantum well (MQW) systems has been studied. The main purpose of our study was to investigate and optimise the epitaxial crystal quality of different QWs structures in order to obtain the best well–barrier system. The strain-compensation technique enabled us to grow InAsP/InGaP-MQWs with strain exceeding ±1% and as many as 20 wells without any material deterioration. The strain-compensated structures have been grown by metalorganic vapor phase epitaxy (MOVPE) using TertiaryButylArsine (TBAs) and TertiaryButylPhosphine (TBP) as group V precursors. Photoluminescence (PL), High-Resolution X-ray Diffraction (HR-XRD), Transmission Electron Microscopy (TEM) have been used to study the MQW structures. Net strain, shear strain and residual strain have been used to evaluate the strain effects on the material quality: strain compensation and abruptness of MQW interfaces are needed in order to obtain high performance material. In addition, in this system, the experimental data suggest that the influence of the strain compensation at the interface between well and barrier, which we define as ‘symmetrical’ strain, seems to be important in determining the quality of the MQW stacks.

The effect of group V precursor on selective area MOVPE of InP/GaAs-related materials

Tertiarybutylphosphine (TBP) and tertiarybutylarsine (TBAs) are widely used as alternative group V precursors for phosphine and arsine, mainly because of their comparatively low toxicity and low decomposition temperature. In this work, the effect of group V precursors on selective area metal-organic vapor phase epitaxy (MOVPE) of InP/GaAs-related materials was studied, in terms of the surface sticking probabilities of group III intermediates. The sticking probabilities were measured by analyzing the thickness profiles of selectively grown films of GaAs and InP in 380-μm-wide growth area between SiO 2 masks. The sticking probability of the In precursor was about 3.2 times larger in the growth with PH 3 than with TBP at 823 K. The sticking probability of the Ga precursor was nearly the same whether the group V source was AsH 3 or TBAs. Such differences were manifested in the In/Ga ratio of selectively grown In x Ga 1− x P. The difference in the sticking probabilities between the precursors of In and Ga mainly determined the In/Ga ratio. Based on a linear combination model using measured values of sticking probabilities, the variation of the composition was predicted to be larger in the growth with phosphine than with TBP. Measurement of the In/Ga composition using electron-probe micro analysis confirmed that prediction. It was proved that the kind of group V precursor is an important factor that governs composition uniformity in selective area MOVPE.

Arsenic incorporation into InGaAsP grown by low-pressure metalorganic vapor phase epitaxy using tertiarybutylarsine and tertiarybutylphosphine in N2 ambient

In x Ga 1−x As y P 1−y epilayers have been grown by low-pressure metalorganic vapor phase epitaxy (LPMOVPE) using tertiarybutylarsine (TBA) and tertiarybutylphosphine (TBP) as group V precursors and nitrogen as the carrier gas. Arsenic incorporation into InxGa1−xAsyP1−y films grown by LPMOVPE as a function of the gas phase composition ratio and V/III ratio has been systematically studied. With optimized growth conditions, the arsenic composition of the epilayers does not change linearly with the TBA source flow. It is observed that the arsenic incorporation becomes saturated when the gas phase composition TBA/(TBA+TBP) increases to 0.4. The incorporation kinetics in MOVPE growth of InxGa1−xAsyP1−y alloy has been analyzed by using an adsorption-trapping model. The As composition (y) of the InxGa1−xAsyP1−y films varies with the TBA gas phase composition ξ=TBA/(TBA+TBP) according to the expression y=2Ns*/aN0(1−e−θβξ). It is demonstrated that with the optimized growth conditions, TBA has a higher incorporation efficiency than TBP in MOVPE growth of InxGa1−xAsyP1−y films.

MOVPE growth of Si-doped GaAs and Al xGa 1− xAs using tertiarybutylarsine (TBA) in pure N 2 ambient

The effects of Si-doping on the growth of GaAs and Al x Ga 1− x As alloy in MOVPE system using tertiarybutylarsine (TBA) in a pure N 2 ambient have been studied. For Si-doped GaAs, the electron carrier concentration increases to a maximum of 3.4×10 18 cm −3 with the increase of SiH 4 flow rate, and then decreases with any further increase of SiH 4 flow rate. For Al x Ga 1− x As with Al concentration x=0.52 the electron carrier concentration reached to a maximum of 3.3×10 17 cm −3. The Al x Ga 1− x As alloy grown in a nitrogen ambient has a lower Al concentration than the one that grown normally in an H 2 ambient. It has also been found that the Al content of the alloy decreases with an increase of silane concentration for a constant group V/III ratio during the MOVPE growth.

Alternative-precursor metalorganic chemical vapor deposition of self-organized InGaAs/GaAs quantum dots and quantum-dot lasers

Metalorganic chemical vapor deposition of laser diodes based on triple stacks of self-organized InxGa1−xAs/GaAs quantum dots (QDs) as active medium using the alternative precursor tertiarybutylarsine (TBAs) is reported. Epitaxy of monodispersed QDs using TBAs is demonstrated. Due to the high cracking efficiency of TBAs at low temperatures, the crucial growth parameters V/III ratio and temperature can be tuned almost independently. Ridge-waveguide QD lasers show a transparency current of 29.7 A/cm2—equivalent to 9.9 A/cm2 per QD layer—an internal quantum efficiency of 91.4%, and an internal optical loss of 2.2 cm−1.

MOVPE growth of InAlAs using TBAs and DitBuSi for HEMT applications

InP-based high electron mobility transistors (HEMTs) are preferable for 40 GHz applications and beyond due to their low noise figure and the achievable high frequencies. We will report on the MOVPE growth of the required epitaxial InAlAs layers using the liquid precursors tertiarybutylarsine (TBAs) and ditertiarybutylsilane (DitBuSi). The Si, O and C concentrations of the InAlAs as function of the growth conditions will be discussed and it was observed that DitBuSi getters oxygen species and is the main unintentional carbon source for Si–InAlAs. Fabricated HEMTs show maximum oscillation frequencies f max of 210 GHz. Further data on material characteristics, uniformity and device performance will be discussed.

Studies of MOVPE growth conditions for the improvement of GaInAsN on GaAs substrates for 1.3 μm laser emission

Metal organic vapor phase epitaxy (MOVPE) growth conditions for the preparation of GaInAsN/GaAs single quantum wells (SQW) have been investigated using tertiarybutylarsine (TBAs) and dimethylhydrazine (DMHy) as arsenic and nitrogen precursors, respectively. We found that a low reactor pressure is required to minimize the effect of the DMHy injection on the indium composition of GaInAsN alloys. We have also established that a high TBAs/III ratio results in a significant improvement of the crystal quality GaInAsN/GaAs SQWs when it is combined with a low growth rate and a low growth temperature. As a result of such optimisation, the photoluminescence (PL) intensity of SQWs emitting at 1.3 μm could be increased by one order of magnitude and the PL line width could be reduced by half compared with more standard conditions using a lower TBAs/III ratio. The lasing threshold of optimised GaInAsN lasers emitting at 1.24 μm could be reduced by a factor of 6. We achieved photoluminescence emission at wavelengths up to 1.35 μm and lasing at 1.26 μm with a threshold as low as 540 A/cm 2 for a cavity length of 1220 μm.

Arsenic incorporation and growth mode of GaNAs grown by low-pressure metal-organic chemical vapor deposition

GaNAs epilayers were grown on GaN/sapphire substrates by low-pressure metal-organic chemical vapor deposition. Tertiarybutylarsine (TBAs) was used as the As source. The As contents in the GaNAs epilayers was measured by secondary ion mass spectrometry, and the surface morphology was studied by atomic force microscopy. The As contents in GaNAs increased drastically with decreasing growth temperature, and became saturated at 5×10 20 cm −3 at 565°C. This As incorporation behavior is attributed to the temperature dependence of NH 3 decomposition and the weaker Ga–As bond. When GaNAs was grown above 565°C, the GaNAs surface was granular with typical granule size of several ten nm. Size and density of the granules depend on the TBAs flow rate. At 530°C, not only a GaN phase but also a GaAs phase was observed by X-ray diffraction with very large islands on a flat surface. It is believed that excessive As incorporation results in the formation of large islands.