Abstract
The effect of the gaseous atmosphere in the growth of gallium arsenide (GaAs) films was studied. The films have been grown by close-spaced vapor transport (CSVT) technique in a home-made hot filament chemical vapor deposition (HFCVD) reactor using molecular hydrogen and molecular nitrogen as the transport agent. An important point about the gaseous atmosphere is the ease in creating volatile compounds when it makes contact with the GaAs source, this favors the transport of material in a CSVT system. Chemical reactions are proposed in order to understand the significant difference produced from the gaseous atmosphere. The films grown with hydrogen are (almost) continuous and have homogeneous layers with preferential orientation (111). The films grown with nitrogen are granular and rough layers with the coexistence of the orientations (111), (220) and (311) in the crystals. The incorporation of impurities in the films was corroborated by energy dispersive spectroscopy (EDS) showing traces of oxygen and nitrogen for the case of the samples obtained with nitrogen. Films grown in a hydrogen atmosphere show a higher band gap than those grown in a nitrogen atmosphere. With the results of XRD and micro-Raman we observe a displacement and broadening of the peaks, characteristic of a structural disorder. The calculations of the FWHM allow us to observe the crystallinity degree and determine an approximate crystallite size using the Scherrer’s equation.
Highlights
gallium arsenide (GaAs) is a semiconductor compound used in some diodes, field-effect transistors (FETs), and integrated circuits (ICs)
Two different deposition times were established, which were aGaAs temperature approximated at 830 mobility layer growth, the electronic is negatively affected [2,15]
1 shows the scheme of the close-spaced vapor transport (CSVT) setup used in this work
Summary
GaAs is a semiconductor compound used in some diodes, field-effect transistors (FETs), and integrated circuits (ICs) It has high carrier mobility, a high optical absorption coefficient and a direct bandgap energy of Eg = 1.42 eV [1]. The CSVT method has been successfully used to grow a variety of thin films semiconductor materials, including homo-and hetero-epitaxial GaAs films [7] This technique has some advantages compared to the other ones. The problem was that due to the incorporation of oxygen in the GaAs layer growth, the electronic mobility is negatively affected [2,15] To avoid this effect, atomic hydrogen has been used as the transport agent to create volatile compounds [12,13,16]. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), micro-Raman spectroscopy, UV-VIS spectroscopy and X-ray diffraction (XRD) were the techniques used in this study
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