Morphology and electrical properties of Pb_1−xCd_xTe/CdTe heterostructures

¹ Material Physic Department, Universidad Autónoma de Madrid, Madrid 28049, Spain
² Compound Semiconductors Group, Faculty of Chemistry, Universidad de la República, Montevideo 11800, Uruguay
³ Microelectronic Institute of Madrid, CNM-CSIC, c/ Isaac Newton 8 (PTM), Tres Cantos 28760, Madrid, Spain

Corresponding author: edgardo.saucedo@uam.es

Received: 4 July 2003
Accepted: 28 January 2004
Published online: 15 July 2004

Abstract

The first experimental results about the growth and characterization of Pb_1−xCd_xTe new high-Z ternary alloy, grown by Vapour Phase Epitaxy (VPE) onto CdTe single crystal substrates are presented. SEM images have shown a well-defined interface between the substrate and the heterostructure bulk, without voids or inclusions. EDX analysis in a line scan mode was done over the layer crossections. The Te, Pb and Cd concentration profiles were found, verifying a strong inter-diffusion in the metallic sublattices and confirming the existence of the Pb_1−xCd_xTe ternary alloy. This has been also confirmed by X-ray diffraction measurements. For the longest growth times, two types of surface defects arose: PbTe aligned microcrystals and cylindrical-like Te-rich structures. Hall measurements showed that the carrier concentration of the layers decreases and the resistivity increases when the growth temperature increases. The influence of the surface defects on the electrical properties was also demonstrated.