Dr Manon Lourenco obtained her first degree and MSc in Physics from the Universidade Federal de MInas Gerais, Brazil, and her PhD from the University of Surrey. She has been working as a research fellow since the completion of her PhD.
My main research interests are directed towards the fabrication and characterisation of optoelectronic devices. During my PhD program, and since then, I have been working on the fabrication and optical, electrical and/or structural characterisation of semiconductor devices (solar cells and light emitting devices) and materials (SIMOX, FeSi2, SiC and other Si compounds; GaAs/InGaAs, InP/InGaAs, CdS/CdTe), using techniques such as electroluminescence, photoluminescence, Raman spectroscopy, deep level transient spectroscopy, photoconductive resolved frequency spectroscopy and double crystal x-ray diffraction. I have published over 50 refereed papers in these areas.
This study reports the effect of an increasing ion dose on both the electrical activation yield and the characteristic properties of implanted bismuth donors in silicon. A strong dependence of implant fluence is observed on both the yield of bismuth donors and the measured impurity diffusion. This is such that higher ion concentrations result in both a decrease in activation and an enhancement in donor migration through interactions with mobile silicon lattice vacancies and interstitials. Furthermore, the effect of implant fluence on the properties of the Si:Bi donor bound exciton, D0X, is also explored using photoluminescence (PL) measurements. In the highest density sample, centers corresponding to the PL of bismuth D0Xs within both the high density region and the lower concentration diffused tail of the implanted donor profile are identifiable.
This study reports on high energy bismuth ion implantation into silicon with a particular emphasis on the effect that annealing conditions have on the observed hyperfine structure of the Si:Bi donor state. A suppression of donor bound exciton, D0X, photoluminescence is observed in implanted samples which have been annealed at 700 °C relating to the presence of a dense layer of lattice defects that is formed during the implantation process. Hall measurments at 10 K show that this implant damage manifests itself at low temperatures as an abundance of p‐type charge carriers, the density of which is observed to have a strong dependence on annealing temperature. Using resonant D0X photoconductivity, we are able to identify the presence of a hyperfine structure in samples annealed at a minimum temperature of 800 °C; however, higher temperatures are required to eliminate effects of implantation strain.
Silicon underpins microelectronics but lacks the photonic capability needed for next-generation systems and currently relies on a highly undesirable hybridization of separate discrete devices using direct band gap semiconductors. Rare-earth (RE) implantation is a promising approach to bestow photonic capability to silicon but is limited to internal RE transition wavelengths. Reported here is the fi rst observation of direct optical transitions from the silicon band edge to internal f -levels of implanted REs (Ce, Eu, and Yb); this overturns previously held assumptions about the alignment of RE levels to the silicon band gap. The photoluminescence lines are massively redshifted to several technologically useful wavelengths and modeling of their splitting indicates that they must originate from the REs. Eu-implanted silicon devices display a greatly enhanced electroluminescence effi ciency of 8%. Also observed is the fi rst crystal fi eld splitting in Ce luminescence. Mid-IR silicon photodetectors with specifi c detectivities comparable to existing state-of-theart mid-IR detectors are demonstrated.