Formation of a step-free InAs quantum well selectively grown on a GaAs (111)B substrate

We investigated the possibility of forming a step-free quantum well structure. A step-free InAs monolayer was grown on a selectively grown mesa by controlling surface phases with in-situ monitoring of surface photo-absorption. We selectively grew a GaAs buffer at 800°C and cooled the sample keeping the (2×2)-like As stabilized surface. Atomic force microscopy (AFM) observation demonstrated that fully step-free surfaces were formed on the 8 μm wide mesa. Then, a monolayer-thick InAs was formed on this step-free surface and this InAs layer was capped by GaAs under the (2×2)-like condition. The quantum level of the step-free InAs layer was evaluated by spatially resolved photoluminescence (μPL) measurement. Uniform PL intensity and the lack of a double layer peak indicated the formation of a step-free InAs quantum well, which was in good agreement with AFM observation.     

Impurity induced disordering of OMVPE-grown ZnSe/ZnS strained layer superlattices by germanium diffusion

We report the first confirmation of disordering of ZnSe/ZnS strained layer superlattices (SLSs) by Ge diffusion. The as-grown sample showed ±first orders of well-resolved double crystal x-ray satellite peaks due to SLS periodic structure. However, the satellite peaks completely disappeared in the Ge-diffused sample, indicating that the SLS structure was disordered by the Ge diffusion. Photoluminescence measurements at 1.4K of both the as-grown and the annealed samples without Ge diffusion show identical, sharp excitonic emission around 420 nm. After Ge diffusion, the PL peaks shift to higher energy confirming the layer disordering of the SLS.     

A1.3 μm strained quantum well laser on a graded InGaAs buffer with a GaAs substrate

We grew a 1.3 μm strained-layer quantum well (SL-QW) laser with InGaP cladding layers on a lattice-relaxation buffer layer by metalorganic vapor phase epitaxy. For the lattice-relaxation buffer, we used a compositionally graded InGaAs/GaAs structure. The significantly reduced surface roughness of the InGaP cladding layers achieved by supplying a large amount of H₂Se enables CW operation of our 1.3 μm SL-QW laser. We achieved a low threshold current of less than 10 mA and a high characteristic temperature of 100K around room temperature.     

Growth and properties of Hg1-xCdxTe on GaAs,with x − 0.27

The organometallic vapor phase epitaxy of HgCdTe onto (100)2°-(110) GaAs substrates is described in this paper. A buffer layer of CdTe has been grown prior to the growth of HgCdTe, to take up the large lattice mismatch with the GaAs. Considerations for the thickness of this buffer layer are outlined, and it is shown by quantitative Secondary Ion Mass Spectroscopy that there is negligible diffusion of gallium from the GaAs substrate for the growth conditions described. Hall effect measurements give mobilities comparable to those reported for bulk grown crystals. An extrinsicn-type carrier concentration of 2 × 10¹⁶/cm³ is obtained, and is mainly due to residual impurities in the starting chemicals. The alloy composition has been determined at 298 K by Fourier transform infrared transmission (FTIR) spectrometry; this is found to be extremely uniform over a 15 × 7 mm area, as evidenced by an overlapping of FTIR plots taken over this area. HgCdTe layers have been grown on buffer layers varying in thickness from 0.1 to 1.9μm. It is found that a buffer thickness of about 1.9μm or larger is required to obtain high quality HgCdTe, both in terms of the electrical characteristics (mobility and carrier concentration) and the infrared transmission curves (peak transmission).     

InP的MOVPE生长

我们利用自制的常压MOVPE设备和国产的三甲基钢以及进口的磷烷生长了InP外延材料,其77K迂移率为65300cm²/V·s,据我们所知这是国内迄今为止用各种方法获得的InP薄膜的最大低温迁移率值。     

The properties of MOVPE grown 1.3 μm DFB MQW lasers infilled with semi-insulating InP fabricated on semi-insulating substrates

The use of optoelectronic integrated circuits (OEICs) is now emerging as a practical technology for a variety of applications, particularly in advanced telecommunications. OEICs consist of a range of devices such as lasers, waveguides, modulators, amplifiers, transistors, detectors, etc. fabricated on the same substrate. When a semi-insulating substrate is used, these devices can be electrically isolated by channel etching, resulting in a low capacitance structure with reduced electrical interference between the subcomponents. One of the devices which is particularly advantageous for this type of integration scheme is the distributed feedback (DFB) laser. The laser can be made to function more efficiently by minimizing the current flowing outside the active region. This can be achieved by surrounding the active region with semi-insulating iron doped InP. This work describes for the first time, the MOVPE growth, fabrication, and device characterization of 1.3 um buried heterostructure DFB MQW lasers, which combine the advantages of using both a semi-insulating substrate and a semi-insulating infill region in the same device structure. The potential advantage of this design scheme is improved OEIC performance as a result of, reduced capacitance and electrical crosstalk, enhanced laser output power, higher speed, increased efficiency, wider operating temperature and reduced threshold current. The laser active region consists of 8 x 140 Å quantum wells of GalnAsP (λ = 1.3 μm) and 110 Åbarriers of GalnAsP (λ= 1.07 μm). Single mode 1.3 urn devices of length 250 μm operating at room temperature produced threshold currents of 8 mA, efficiencies of up to 25%, output powers of 18 mW at 80 mA (pulsed), and a frequency response greater than 12GHz. The parasitic capacitance was estimated to be less than 3 pF.     

Metalorganic InP and Inx Ga1-x,Asy P1-y,on InP epitaxy at atmospheric pressure

We present a procedure for the MOVPE of InP as simple as the one currently used for GaAs. InP and InGaAsP alloys are grown on InP substrates using trimethy1indium (TMI), phosphine, trimethylgallium (TMG) and arsine. The choice of carrier gas is important ; a mixture of hydrogen and nitrogen allowed us to grow uniform layers over large areas at atmospheric pressure, without pyrolizing the phosphine or separating the input reactants. Preliminary characterization results are presented. Most information contained in this paper was presented at the 1983 Electron Materials Conference as paper Cl.     

Structural properties of ZnSy Se1−yZnSe/GaAs (001) heterostructures grown by photoassisted metalorganic vapor phase epitaxy

ZnS_ySe_1−yZnSe/GaAs (001) heterostructures have been grown by photoassisted metalorganic vapor phase epitaxy, using the sources dimethylzinc, dimethylselenium, diethylsulfur, and irradiation by a Hg arc lamp. The solid phase composition vs gas phase composition characteristics have been determined for ZnSy_ySe_1−y grown with different mole fractions of dimethylselenium and different temperatures. Although the growth is not mass-transport controlled with respect to the column VI precursors, the solid phase composition vs gas phase composition characteristics are sufficiently gradual so that good compositional control and lattice matching to GaAs substrates can be readily achieved by photoassisted growth in the temperature range 360°C ≤ T ≤ 400°C. ZnSe/GaAs (001) single heterostructures were grown by a two-step process with ZnSe thicknesses in the range from 54 nm to 776 nm. Based on 004 x-ray rocking curve full width at half maximums (FWHMs), we have determined that the critical layer thickness is h_c ≤200 nm. Using the classical method involving strain, lattice relaxation is undetectable in layers thinner than 270 nm for the growth conditions used here. Therefore, the rocking curve FWHM is a more sensitive indicator of lattice relaxation than the residual strain. For ZnS_ySe_1−y layers grown on ZnSe buffers at 400°C, the measured dislocation density-thickness product Dh increases monotonically with the room temperature mismatch. Lower values of the Dh product are obtained for epitaxy on 135 nm buffers compared to the case of 270 nm buffers. This difference is due to the fact that the 135 nm ZnSe buffers are pseudomorphic as deposited. For ZnS_ySe_1−y layers grown on 135 nm ZnSe buffers at 360°C, the minimum dislocation density corresponds approximately to room-temperature lattice matching (y ∼ 5.9%), rather than growth temperature lattice matching (y ∼ 7.6%). Epitaxial layers with lower dislocation densities demonstrated superior optical quality, as judged by the near-band edge/deep level emission peak intensity ratio and the near band edge absolute peak intensity from 300K photoluminescence measurements.     

On the role of interface properties in the degradation of metalorganic vapor phase epitaxially grown Fe profiles in InP

Fe doping profiles in InP layers grown by low-pressure metalorganic vapor phase epitaxy (LP-MOVPE) were investigated by secondary ion mass spectroscopy. Different pre-treatments of the InP substrates proved to have substantially different effects on the Fe profiles which strongly indicate the relevance of underlying interfaces to dopant diffusion in subsequent layers, at least in the case of dopants occupying the group-III sublattice. We attribute the degradation of Fe profiles observed for some kinds of treatment to the emission of In interstitials from surfaces covered by oxides or other residues which are incompletely removed during the MOVPE preheat cycle. A favorable substrate preparation method for avoiding Fe profile degradation relies on etching by 5:1:1 H₂SO₄:H₂O₂:H₂O at room temperature followed by 30 min deionized water rinsing.     

Growth kinetics of GaSb by metalorganic vapor phase epitaxy

The growth rates of GaSb by metalorganic vapor phase epitaxy were studied as functions of growth temperatures and partial pressures of precursors. A Langmuir-Hinshelwood model was used to explain the GaSb growth rate in the chemical reaction controlled regime. The relationship between growth kinetics and epilayer qualities was discussed and properties of GaSb were obtained.