Micro-Raman and Spreading Resistance Analysis on Beveled Implanted Germanium for Layer Transfer Applications

Raman and spreading resistance profiling have been used to analyze defects in germanium caused by hydrogen and helium implants, of typical fluences used in layer transfer applications. Beveling has been used to facilitate probing beyond the laser penetration depth. Results of Raman mapping along the projection area reveal that after post-implant annealing at 400°C, some crystal damage remains, while at 600°C, the crystal damage has been repaired. Helium implants create acceptor states beyond the projected range, and for both hydrogen and helium, 1×1016 acceptors/cm2 remain after 600°C. These are thought to be vacancy-related point defect clusters.

Use of a novel micro-fluidic device to create arrays for multiplex analysis of large and small molecular weight compounds by surface plasmon resonance

There is an increasing demand to develop biosensor monitoring devices capable of biomarker profiling for predicting animal adulteration and detecting multiple chemical contaminants or toxins in food produce. Surface plasmon resonance (SPR) biosensors are label free detection systems that monitor the binding of specific biomolecular recognition elements with binding partners. Essential to this technology are the production of biochips where a selected binding partner, antibody, biomarker protein or low molecular weight contaminant, is immobilised. A micro-fluidic immobilisation device allowing the covalent attachment of up to 16 binding partners in a linear array on a single surface has been developed for compatibility with a prototype multiplex SPR analyser.

The immobilisation unit and multiplex SPR analyser were respectively evaluated in their ability to be fit-for-purpose for binding partner attachment and detection of high and low molecular weight molecules. The multiplexing capability of the dual technology was assessed using phycotoxin concentration analysis as a model system. The parent compounds of four toxin groups were immobilised within a single chip format and calibration curves were achieved. The chip design and SPR technology allowed the compartmentalisation of the binding interactions for each toxin group offering the added benefit of being able to distinguish between toxin families and perform concentration analysis. This model is particularly contemporary with the current drive to replace biological methods for phycotoxin screening.

Characterization of Nickel Germanide Schottky Contacts for the Fabrication of Germanium p-channel MOSFETs

Nickel germanide Schottky contacts, formed by rapid thermal annealing of thin nickel films, have been characterized on n-type germanium wafers for a range of RTA temperatures. The highest Schottky barrier heights for electrons (= 0.6-0.7 eV) were obtained for RTA temperatures of approximately 300°C. For this RTA schedule, the corresponding barrier height for holes is close to zero, ideal for Schottky contacted p-channel germanium MOSFETs. When the RTA temperature was increased to 400oC, a dramatic reduction in electron barrier height (< 0.1 eV) was observed. This RTA schedule, therefore, appears ideal for ohmic source/drain contacts to n channel germanium MOSFETs. From sheet resistance measurements and XRD characterization, nickel germanide formation was found to occur at 300oC and above. The NiGe phase was dominant for RTA temperatures up to at least 435oC.

(Invited) Germanium on Sapphire Technology

Silicon-on-sapphire (SOS) substrates have been proven to offer significant advantages in the integration of passive and active devices in RF circuits. Germanium on insulator technology is a candidate for future higher performance circuits. Thus the advantages of employing a low loss dielectric substrate other than a silicon-dioxide layer on silicon will be even greater. This paper covers the production of germanium on sapphire (GeOS) substrates by wafer bonding. The quality of the germanium back interface is studied and a tungsten self-aligned gate process MOST process has been developed. High low field mobilities of 450-500 cm2/V-s have been achieved for p-channel MOSTs produced on GeOS substrates. Thick germanium on alumina (GOAL) substrates have also been produced.

Design, Manufacture and Performance of Germanium Bipolar Transistors

Germanium NPN bipolar transistors have been manufactured using phosphorus and boron ion implantation processes. Implantation and subsequent activation processes have been investigated for both dopants. Full activation of phosphorus implants has been achieved with RTA schedules at 535?C without significant junction diffusion. However, boron implant activation was limited and diffusion from a polysilicon source was not practical for base contact formation. Transistors with good output characteristics were achieved with an Early voltage of 55V and common emitter current gain of 30. Both Silvaco process and device simulation tools have been successfully adapted to model the Ge BJT(bipolar junction transistor) performance.