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ABSTRACT There is increasing interest in the epitaxial growth of high quality InSb thin films on GaAs substrates for many device applications such as infrared optoelectronics. The large lattice mismatch (14.6%) between InSb and GaAs has meant that both growth techniques and conditions have a large influence on the interface properties and consequently the film quality. A surface science study, by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) together with Nomarski microscopy, on the surface and interface properties of InSb/GaAs by metalorganic chemical vapor deposition is presented. It is found fromthe XPS data that the ambient surface is composed of InSb, In 20 3, Sb 20 3 and Sb 20 5 . The interdiffusion phenomena are studied by AES depth profiling; the width of interdiffusion region is determined to be 50±10 nm for all the samples grown at different V/III ratios. This is narrower than the data previously obtained for InSb/GaAs interfaces produced by metalorganic magnetron sputtering. The results also demonstrate that uniform and stoichiometric InSb films have been obtained, and that the reproducibility of the MOCVD technique is excellent. INTRODUCTION Indium antimonide (InSb) exhibits the smallest bandgap (0.17 eV), highest intrinsic electron mobility (7 x I05 cm 2/Vs at 77 K), highest maximum electron drift velocity, and lowest electron effective mass among all the binary III-V semiconductor compounds [1-4]. These properties make it a promising candidate for the application of infrared devices, high-speed transistors and magnetic sensors [3-9]. Numerous efforts have been completed to grow high quality, epitaxial InSb on silicon (Si) and gallium arsenide (GaAs) to take advantage of the advanced, mature and relatively low-cost Si and GaAs integration technology. GaAs provides a semi-insulating substrate that facilitates electrical isolation for device application as well as simpler analysis of the electrical properties of the lower bandgap InSb [3]. The epitaxial growth of InSb on GaAs has been achieved through several techniques such as molecular beam epitaxy (MBE) [2-4,6,10], metalorganic chemical vapor deposition (MOCVD) [7,11], and metalorganic/r.f. magnetron sputtering [8,12]. To commercially fabricate InSb-based devices, large-scale production is essential. MOCVD has been proved to be the most promising technique for this purpose [7]. In this paper a vertically configured MOCVD system has been employed to grow InSb films on GaAs substrates for production applications. The aim is to investigate the surface morphology, surface chemical states, bulk chemical composition depth distribution and their 63

Mat. Res. Soc. Symp. Proc. Vol. 484 ©1998 Materials Research Society

relevance to the II/V precursor input ratio. The emphasis is to examine the reproducibility of the MOCVD technique in terms of both surface and bulk chemical compositions.

EXPERIMENT InSb films, 1.4-1.6 pm thick, were grown on GaAs (100) substrates using a low pressure

MOCVD system of vertical configuration. Th