I. Pietzonka

Isotropic dielectric functions of highly disordered AlxGa1−xInP(0⩽x⩽1) lattice matched to GaAs

Determination of the complex dielectric function and the critical-point energies of (AlxGa1−x)0.51In0.49P, over the full range of composition x and for photon energies E from 0.75 to 5 eV is reported from variable angle of incidence spectroscopic ellipsometry. Native-oxide effects on the (AlxGa1−x)0.51In0.49P optical functions are removed numerically. The highly disordered state of the metalorganic vapor-phase epitaxy grown samples is analyzed by transmission electron microscopy. Optical anisotropy investigations revealed that the order-induced optical birefringence is negligible throughout. The augmentation of A. D. Rakic and M. L. Majewski [J. Appl. Phys. 80, 5909 (1996)] to Adachi’s critical-point model, i.e., consideration of Gaussian-like broadening function instead of Lorentzian broadening, is used for calculation of the isotropic (AlxGa1−x)0.51In0.49P dielectric function ∈. The optical functions spectra consistently match the experimental data, whereas previously reported model dielectric functions...

Systematic study of the surface morphology of ordered (GaIn)P

Abstract The surface morphology of CuPtB-type ordered (GaIn)P, lattice-matched grown on (001)GaAs by low-pressure MOVPE, was systematically investigated by means of atomic force microscopy. Since surface steps, e.g. provided by different misorientations of the substrates, are known to affect the ordering behaviour, the superstep distances and heights are examined in order to correlate the surface structure to the existing ordering. In order to correlate both surface morphology and ordering, experiments have been performed varying the growth parameters and the partial pressure of the phosphorous precursors phosphine (PH3), tertiarybutylphosphine (TBP) and ditertiarybutylphosphine (DitBuPH), and finally the Zn doping concentration. From these results, in addition to previously reported data [S.H. Lee, G.B. Stringfellow, J. Appl. Phys. 83 (1998) 3620], generally valid dependencies for the superstep distances, superstep heights, and the degree of ordering are derived and interpreted.

MOVPE growth and characterization of GaInAs(P) on (001) InP using diethyltertiarybutylarsine (DEtBAs) and tertiarybutylphosphine (TBP) as the group-V sources

We report on low pressure MOVPE results of (GaIn)As grown with the arsenic precursor DEtBAs as well as (GaIn)(AsP) grown on InP using the precursor combinations DEtBAs/TBP, DEtBAS/PH 3 which we carefully compared with samples grown in the standard system (AsH 3 /PH 3 ). Lattice matched (GaIn)As layers have been obtained at a growth temperature of 600°C, a V/III ratio of 3 and at a growth rate of 1 μm/h at a reactor pressure of 50 mbar. Changing the As precursor from AsH 3 to DEtBAs simultaneously alters the incorporation coefficient ratio k Ga /k In from 1.15 to 1. At room temperature n-type mobilities of 9060 cm 2 /V s have been achieved for (GaIn)As grown with DEtBAs at a V/III ratio of 2. Besides the excitonic luminescence at 802 meV a lower energy peak appears in the photoluminescence (PL) spectra at 753 meV (carbon-carbon donor-acceptor pair). The excitonic luminescence peak has a FWHM of about 9 meV. The (GaIn)(AsP) layers have been grown at a growth temperature of 625°C and V/III ratios of 15-25 with DEtBAs/TBP and about 60 with DEtBAs/PH 3 . Layers grown with higher V/III ratios show an enhanced As content. However, considering the P incorporation we have observed a qualitative difference between the standard hydride system and systems using alternative group-V precursors. Even in the system DEtBAs/PH 3 the phosphorus incorporation is much higher than in the AsH 3 /PH 3 system indicating the influence of vapor phase exchange reactions.

Metal organic vapour phase epitaxial growth and characterization of (GaIn)P layers grown with different P-containing precursors

Abstract The suitability of ditertiarybutylphosphine (DitBuPH) for the low-pressure MOVPE growth of (GaIn)P has been investigated. This source is distinguished by a further reduction of the direct H-functions in the molecule, its liquid state and its suitable vapour pressure and is therefore advantageous from the toxicity and safety viewpoint. The optical and structural properties are compared with those obtained using tertiarybutylphosphine (TBP) and PH 3 . Moreover, doping experiments have been carried out using disilane and diethylzinc as dopants. No difference in the growth and doping behaviour for all three used P-sources could be determined and the data are in good agreement with literature values.

Correlation between the surface morphology and antiphase boundaries in ordered (GaIn)P

Abstract The surface of metal-organic vapor-phase epitaxy (MOVPE) grown CuPt B -type ordered (GaIn)P epitaxial layers and their interface to the GaAs substrate have been investigated using high-resolution transmission electron microscopy (HRTEM). We find the (GaIn)P surface to consist of bunched supersteps, (001) terraces, and vicinal regions. The dependence of the height and the density of supersteps, the portion of monolayer steps contained in supersteps as well as the density of antiphase boundaries on the growth temperature and the substrate misorientation is investigated. By comparing the densities of the supersteps and the antiphase boundaries on the (GaIn)P surface and at the interface to GaAs, we find that the supersteps at the interface are the preferential formation site of antiphase boundaries in (GaIn)P. The correlation is disturbed, however, by the effect of the width of supersteps and (001) terraces and of the existence of vicinal regions on the APB formation.

MOVPE Growth and Characterisation of Zn-Doped (GaIn)P Layers with Respect to Surface Structure and Ordering

(GaIn)P grown on (001)GaAs substrates by metal-organic vapour phase epitaxy (MOVPE) is highly ordered material. In this work the effect of Zn doping on the epitaxial crystal growth, the ordering behaviour and the surface morphology is investigated. Zn-doped (GaIn)P layers, grown with phosphine (PH 3 ), tertiarybutylphosphine (TBP) and ditertiarybutylphosphine (DitBuPH) as phosphorous precursors, reveal a strong drop of the binary growth rate of InP r InP with increasing Zn/III ratio, whereas r GaP remains nearly constant. The Zn doping efficiency and the ordering behaviour are observed to be dependent on the misorientation of the substrates. Finally, the surface morphology as a function of the different parameters was analysed by atomic force microscopy (AFM), and no considerable change of the growth mechanism was found for Zn-doped layers in comparison to undoped layers.