Thermal decomposition studies and low pressure metalorganic vapour phase epitaxy (MOVPE) growth experiments have been performed using novel, less toxic arsinetrialkyl sources, which decompose by the β-hydride elimination process. Therefore, As–H functions are automatically formed in the hot temperature zone of the MOVPE reactor to enable high quality layer deposition. Decomposition studies have been carried out under growth conditions in the MOVPE reactor by quadrupole mass spectroscopy (QMS). The β-elimination decomposition of the novel As-sources diethyltertiarybutyl-arsine (DE t BAs) and diethylisopropyl-arsine (DE i PrAs) is proven by the detection of the cracking products diethylarsine (DEAsH) and the corresponding alkene fragments isobutene ( C4H8) and propene ( C3H6), respectively. The alkene-to-radical formation for different As- and P-precursors indicate a β-elimination efficiency of about 60% for tertiarybutyl- and 40% for isopropyl-groups, whereas for ethyl groups no significant indication of a β-elimination has been observed. GaAs bulk layers were grown by using trimethylgallium (TMGa) in combination with the β-eliminating As-trialkyl sources DE t BAs and DE i PrAs, respectively, as well as by using TEAs or DEAsH, both decomposing under ethyl-radical formation. In addition, the partially fluorinated source pentafluorethyl-diisopropyl-arsine (PFED i PrAs) has been investigated, however, only an etching of the GaAs substrate surface could be detected independently of the growth conditions. The use of β-eliminating As-trialkyl compounds leads to significantly improved layer properties as compared to TEAs-grown structures. GaAs layers, grown with DE t BAs or DE i PrAs at substrate temperatures of 600–650° C and V/III ratios between 8 and 80 exhibit p-type behaviour with net carrier concentrations of 3–5×1015 cm-3 and hole mobilities of 350–400 cm2/ V·s at 300 K and 3500–4100 cm2/ V·s at 77 K. Carbon is the dominant acceptor impurity in GaAs layers at present, as determined by PL spectroscopy. These results indicate a promising potential of the class of β-eliminating As-compounds as replacements for arsine in the MOVPE.
We discuss the performance and reliability of oxide confined VCSELs optimized for datacom applications. The dcvices are employed in thc Siemens PAROLITM [ I ] high performance parallel optical link. This optical link provides 12 parallel channels with a total bandwidth exceeding 12GbiUs. The VCSEL threshold current is approximately 3mA. The thi-eshold current variation within the array is less than 50pA.The electrical series resistance is about Son. The emission wavelength of appro.rtimately XS0nm matches the specification of common standards like the HIPPI 6400. Life times of the oxide confined VCSELs are several million hours under normal operating conditions. The life time for an array drops compared tu a single device, but is still larger than 1 million Ihours. The devices exhibit Sood stability under cnvironmental stress conditions such as temperature cycling and damp heat storage.
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