The study of carbon incorporation during growth in epitaxial indium antimonide layers prepared by metalorganic magnetron sputtering

Abstract

Secondary-ion mass spectrometry and Auger electron spectroscopy measurements combined with Hall data have indicated high levels of electrically active carbon impurities in InSb films grown by metalorganic magnetron sputtering. Background impurity concentrations in the range of 5 X cm-3 were observed for films grown at optimum deposition conditions. While it was also observed that the level of carbon in the layers decreased with increasing substrate temperature and V-111 ratio, the addition of small amounts of molecular hydrogen (H,) to the sputtering gas resulted in an order of magnitude decrease in the carbon content of the as-grown InSb layers. Mass spectrometric studies suggest that the major source of carbon contamination in the layers is the methyl radicals produced from the pyrolysis of trimethylindium.Des mesures de spectromCtrie de masse des ions secondaires et de spectroscopie des Clectrons Auger, combinees avec des donnCes d'effet Hall ont indiquC l'existence de hauts niveaux dlimpuretC de carbone Clectriquement actives dans des couches de InSb prCparCes par pulvCrisation magnCtron d'organomCtalliques. Des concentrations d'impuretks de l'ordre de 5 x loL8 cm-3 ont Ct C observCes pour des couches dCposCes dans des conditions optimales. Alors qu'on observait aussi que le niveau de carbone dans les couches diminuait avec un accroissement de la temperature du substrat et du rapport V-111, l'addition de petites quantitCs d'hydrogkne moltculaire (H,) au gaz de pulvCrisation avait cornme resultat une diminution d'un ordre de grandeur dans le contenu en carbone des couches deposkes. Des Ctudes par spectromCtrie de masse indiquent que la source majeure de contamination par le carbone provient des radicaux mCthyles resultant de la pyrolyse de I'indiumtrimCthyle.[Traduit par la revue]Can. J. Phys. 67, 298 (1989) 1. Introduction Recently we reported on the hetero-and homo-epitaxial growth of indium antimonide (InSb) on GaAs and InSb substrates using a novel deposition technique, metalorganic magnetron sputtering (MOMS) (1, 2). The growth of InSb by MOMS involves magnetron sputtering a high-purity antimony (Sb) target in a reactive atmosphere of a metalorganic such as trimethylindium (TMI). It was shown in these earlier works that InSb films exhibiting a high degree of crystalline perfection and with "mirrorlike" surface morphologies could be obtained using MOMS. However, Hall-effect measurements on these films indicated a relatively high level of background impurities. Recent secondary-ion mass spectrometry (SIMS) analysis of these InSb layers revealed relatively large residual carbon impurity concentrations, similar to those observed in films prepared by other deposition techniques employing metalorganics. For instance, carbon has been identified as one of the major impurities found in epitaxial GaAs layers grown by metalorganic vapour-phase epitaxy (MOVPE) (3) or metalorganic molecular-beam epitaxy (MOMBE) (4) using metalorganic sources such as trimethylgallium (TMG).In GaAs layers grown using MOVPE, it has be...