IOP PUBLISHING JOURNAL OF PHYSICS D: APPLIED PHYSICS J. Phys. D: Appl. Phys. 40 (2007) 1351–1356 doi:10.1088/0022-3727/40/5/007 Influence of He-ion irradiation on the characteristics of Pd/n-Si 0.90 Ge 0.10 /Si Schottky contacts M Mamor, A Sellai, K Bouziane, S H Al Harthi, M Al Busaidi and F S Gard Physics Department, Sultan Qaboos University, PO Box 36 Muscat 123, Sultanate of Oman E-mail: mamor@squ.edu.om Received 20 December 2006, in final form 15 January 2007 Published 16 February 2007 Online at stacks.iop.org/JPhysD/40/1351 Abstract Current–voltage (I –V ) and capacitance–voltage (C–V ) characteristics of He-ion irradiated Pd/n-Si 09 Ge 0.10 Schottky contacts have been measured in the temperature range from 100 to 300 K. Schottky barrier properties such as the Schottky barrier height ( bn ) and ideality factor (n) have been studied as a function of temperature. The degree to which their characteristics deviated from the ideal case increased as the temperature decreased. A decrease in  bn and an increase in n with decreasing temperature are observed. Additionally, linear dependence between the so-called temperature factor T 0 and temperature as well as between  bn and n are shown. This type of strong temperature dependence indicates the presence of a large degree of lateral inhomogeneities of the barrier height, resulting from the He-ion irradiation induced defects and traps which produce a variation in the number of free carriers. The presence of electrically active defects introduced by He-ion irradiation at and below the Si 0.90 Ge 0.10 surface support this interpretation. 1. Introduction There has been considerable interest in integrating high speed and novel devices made from Si 1−x Ge x materials [1], since the alloy is compatible with the silicon based technology. The band structure of strained layers can be engineered by varying the Ge concentration, which has made it possible to fabricate a large family of devices such as heterojunction bipolar transistors [2], modulation doped field effect transistors [3] and infrared photodetectors [4]. In compound semiconductors, ion implantation is particularly attractive due to its many promising applications in integrated devices and is widely used during several electronic devices fabrication steps. In particular, ion implantation is used to improve the fast switches [5] and the performance of photodiodes [6]. Moreover, it is well known that ion implantation into semiconductor materials has a profound influence on the structural and electronics properties of their surface and subsurface region, and hence governs the characteristics of metal contacts formed on the semiconductor [7]. It has been also shown that ion implantation induces defects in the band gap which affects the free carriers concentration and leads to an increase (decrease) of barrier height in p- type (n-type) semiconductors [8, 9]. The knowledge of the influence of radiation damage on the Schottky barrier diodes (SBDs) performance is a fundamental field of research, having technological relevance for many applications in the semiconductor electronic devices. The influence of ion implantation induced changes of Schottky barrier height (SBH) in silicon and GaAs has been reported [10, 11]. However, improving the SiGe based device processing requires an understanding of the electrical properties of Metal/Si 1−x Ge x /Si SBDs subjected to ion implantation. It is, therefore, imperative to investigate the effect of ion implantation on the electrical characteristics of Metal/Si 1−x Ge x /Si SBDs. Although the electrical characterization of Schottky barrier junctions (SBJs) fabricated on non-implanted Si 1−x Ge x samples is well conducted [12–14], little is known about the effect of ion irradiation on the electrical properties of Schottky diodes fabricated on Si 1−x Ge x . Moreover, most of the studies of SBDs on Si 1−x Ge x were limited to the effect of Ge-content on the SBH. In previous studies we have demonstrated that 0022-3727/07/051351+06$30.00 © 2007 IOP Publishing Ltd Printed in the UK 1351