Growth of PbTe films by magnetron sputtering
- PDF / 438,522 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 46 Downloads / 237 Views
Growth of PbTe films by magnetron sputtering A. Jdanov, J. Pelleg, Z. Dashevsky and R. Shneck Department of Materials Engineering, Ben Gurion University of the Negev, Beer Sheva, 84105, ISRAEL ABSTRACT Thin films of PbTe were deposited on Si (111) wafers and glass substrates at a constant power for different times and at a constant time at various power levels. In some cases substrate heating to a temperature of ~673K was performed during sputtering. Structural analysis by Xray diffraction (XRD) and high-resolution electron microscopy (HRTEM) were performed. The composition of the PbTe film was evaluated by Auger depth profile. At an appropriate combination of power and deposition time only (200) and its higher order peaks were observed in the PbTe film. It is expected that it is feasible to obtain epitaxial PbTe film by RF magnetron sputtering. INTRODUCTION PbTe semiconductor is of interest due to its potential application as a thermoelectric material, an infrared detector and a semiconductor laser in the 3-30 µm range. For its use in any of the above applications epitaxial PbTe on Si wafers is desirable. In particular the monolithic integration of narrow gap AIVBVI semiconductors and Si devices is highly attractive for infrared (IR) optoelectronic applications. Epitaxial growth of PbTe semiconductor on Si wafers is required [1]. The growth of epitaxial PbTe is hindered by the large mismatch of ~19% between the lattice parameters of PbTe and the Si substrate and the considerable difference in their thermal expansion coefficients [2]. Usually some intermediate buffer layer solves the mismatch problem. Fluoride buffer layers, such as CaF2 and BaF2, are generally used to reduce thermal and lattice strains [3]. Epitaxial growth of PbTe films directly on the Si wafer is desirable for simplification of the fabrication process. Furthermore, it might be of interest to investigate the effect of an oxide such as SiO2 also on the PbTe properties [4]. In the present work the growth of PbTe thin film deposited on Si (111) substrate by RF magnetron sputtering is addressed. In order to optimize the conditions of the process, the depositions of PbTe on the Si wafers was performed by varying the power while maintaining the time constant or by keeping a constant power and altering the time. X-ray diffraction (XRD), Auger spectroscopy and high-resolution electron microscopy (HRTEM) were used to characterize the film. EXPERIMENTAL DETAILS In our attempt to eliminate the use of buffer layers and simplify the PbTe fabrication process, thin films were grown on Si substrates by RF magnetron sputtering. Simultaneously with the silicon, glass substrates were also used for comparison purposes. The base pressure before introducing Ar in the sputter chamber was ~6.7x10-5 Pa. The PbTe target was presputtered in Ar ambient at a pressure of 0.6 Pa for about 30min and it was followed by sputtering at the same Ar pressure. The deposition of the PbTe films to a thickness of 80-200 nm was performed with a deposition rate of about 0.1 nms-1. The films
Data Loading...
