Dose rate dependence of residual defects in device grade Si/SiGe heterostructures formed by ion beam synthesis
Nejim, A., Cristiano, F., Knights, A. P., Barradas, N. P., Hemment, P. L. F. and Coleman, P. G. (1998) Dose rate dependence of residual defects in device grade Si/SiGe heterostructures formed by ion beam synthesis Proceedings of the 1998 International Conference on Ion Implantation Technology, 2. pp. 692-695.
The influence of germanium ion current density on the residual defects in ion implanted Si/SiGe heterostructures is investigated. Data from (100) silicon wafers implanted with 400 keV 9×1016 Ge+/cm2 shows that both the nature and concentration profile of residual defects below the amorphised silicon surface layer are highly sensitive to the Ge+ current density. Dose rates in the range of 7.3×1012 Ge+/s.cm2 and 1.5×1012 Ge+/s.cm2 corresponding to power loading of 0.47 W/cm2 and 0.09 W/cm2 respectively, were investigated in this study. The nature and concentration of the defects was investigated by Rutherford Backscattering Channelling analysis (RBS-c), cross section Transmission Electron Microscopy (xTEM) and Positron Annihilation Spectroscopy (PAS) in conjunction with anodic oxidation and wet etching. RBS-c indicates that by increasing the dose rate from 5 microA/cm2 to 13 microA/cm2 reduces the thickness of the amorphous layer from 550 nm to 350 nm. A further increase to 20 microA/cm2 inhibits the formation of an amorphous layer due to dynamic annealing. This is associated with a significant increase in the depth profile of interstitial defects down to a depth of 800 nm. As in the case of interstitial defects, there is a considerable enhancement in the depth and concentration of open volume defects with increasing dose rate found by PAS analysis. For the highest dose rate open volume defects extend beyond 1.5 micro-m at a concentration in excess of 1×1016/cm2. Post amorphisation with Si+ implantation removes all the Ge+ implant related defects leaving strain related defects and deep band of end of range defects.
|Divisions :||Faculty of Engineering and Physical Sciences > Electronic Engineering > Advanced Technology Institute > Ion Beam Centre|
|Date :||22 June 1998|
|Additional Information :||Nejim, A., Cristiano, F., Knights, A.P., Barradas, N.P., Hemment, P.L.F., & Coleman, P.G. (1998). Dose rate dependence of residual defects in device grade Si/SiGe heterostructures formed by ion beam synthesis. Proceedings of the 1998 International Conference on Ion Implantation Technology (22-26 June 1998), Vol. 2, pp. 692 - 695. © 1998 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.|
|Depositing User :||Mr Adam Field|
|Date Deposited :||27 May 2010 14:39|
|Last Modified :||23 Sep 2013 18:32|
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