Structural properties of Zn-diffused InP layers

Abstract

A sealed tube method has been adopted to prepare Zn-diffused InP layers. Both Zn 3 P 2 and ZnϩInP have been used as sources. The samples were prepared at 500°C. The diffusion time ranged from 5 up to 120 min. Both S-and Zn-doped InP crystals have been used as substrates. The Zn depth profile has been measured by secondary ion mass spectroscopy, while the lattice strain produced by diffusion has been carefully investigated by x-ray double crystal diffraction and the standing-waves method of recording photoelectrons. The results show that in the S-doped crystal the diffused/virgin interface is very sharp and the diffused layers are lattice contracted. The concentration of Zn, as well as the lattice strain, do not depend on the diffusion time, whereas the thickness of the diffused layer increases with time. The plot of diffused layer thickness versus the square root of the diffusion time showed different slopes depending on the diffusion sources. Both lattice strain and diffusion depth depend on the diffusion source, whereas the concentration of Zn is not influenced by the type of diffusion source.

Theoretical considerations about solid-state diffusion of impurities into crystals

“…The growth of bulk material may be carried out in a similar fashion to that used for the well-established germanium and silicon semiconductors but additional problems arise in the purification of crystals and in controlling the high vapour pressures often encountered, especially in the formation of compounds such as phosphides [9], borates [10], tantalates [11], etc. Epitaxial layer deposition from either the vapour or liquid phase, liquid encapsulation [12], and other techniques [13] may overcome the difficulties caused by high vapour pressures and other growth/purification methods.…”