R. Franzheld

Plasma-enhanced chemical vapor deposition of SiOx/SiNx Bragg reflectors

Abstract Optical parameters of amorphous films of SiOx and SiNx deposited by plasma-enhanced chemical vapor deposition (PECVD) were extracted from ellipsometry and transmission spectroscopy in order to design Bragg reflectors. Bragg reflectors with a low number of layer pairs (SiOx/Si and SiOx/SiNx) have been grown on planar substrates for wavelengths ranging from 400 to 1600 nm. The Bragg reflectors prepared at 90 °C were patterned by lift-off processing. The growth behavior of Bragg reflectors on different prepatterned substrates was investigated with regard to micromirror application.

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.

Effects of organic As-precursors on the incorporation of In and Ga into (GaIn)As films grown by metal-organic vapor-phase epitaxy

Abstract We present a detailed study of the incorporation of gallium and indium into (GaIn)As grown by low-pressure metal-organic vapor-phase epitaxy (MOVPE) using the group-V precursors arsine (AsH 3 ), tertiarybutylarsine (TBAs) and diethyltertiarybutylarsine (DEtBAs). We have grown strain-compensated multilayer structures of (GaIn)As layers alternately with AsH 3 and one of the organic sources DEtBAs and TBAs. In order to clarify the origin of the changed solid composition using organic sources, we analyzed X-ray diffraction data by dividing each (GaIn)As layer into a GaAs sublayer and an InAs sublayer. Comparing simulated and measured X-ray diffraction spectra, we find that the use of organic precursors in MOVPE growth increases the In incorporation rate by increasing the InAs growth rate. This effect is even higher for DEtBAs than for TBAs. An As-source-dependent supply of active hydrogen, controlling the In incorporation, as well as vapor phase processes and surface reactions are discussed.

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.